Earless seal: Difference between revisions

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{{Short description|Family of mammals}}
{{Short description|Family of mammals}}
{{distinguish|text=[[Phocides]], a genus of butterflies, [[Pholcidae]], a family of spiders, or [[Phocoenidae]], a family of toothed whales}}
{{distinguish|text=[[Phocides]], a genus of butterflies, [[Pholcidae]], a family of spiders, or [[Phocoenidae]], a family of delphinodea}}
{{Automatic taxobox
{{Automatic taxobox
| name = Earless seals<ref name=msw3>{{MSW3 Wozencraft | pages = | id = 14001028}}</ref>
| name = Earless seals<ref name=msw3>{{MSW3 Wozencraft | pages = | id = 14001028}}</ref>
| image = Seehund.jpg
| image = Seehund.jpg
| image_caption = [[Harbor seal]], ''Phoca vitulina''
| image_caption = [[Harbor seal]], ''Phoca vitulina''
| fossil_range = {{Fossil range|earliest=Chattian|Aquitanian|present}}<small>Early [[Miocene]] – [[Holocene]], possible late [[Oligocene]] record<ref name=Noriphoca>{{Cite journal|author1=Leonard Dewaele |author2=Olivier Lambert |author3=Stephen Louwye |year=2018 |title=A critical revision of the fossil record, stratigraphy and diversity of the Neogene seal genus ''Monotherium'' (Carnivora, Phocidae) |journal=Royal Society Open Science |volume=5 |issue=5 |pages=171669 |doi=10.1098/rsos.171669 |pmid=29892365 |pmc=5990722 |bibcode=2018RSOS....571669D }}</ref></small>
| fossil_range = {{Fossil range|earliest=Chattian|Aquitanian|present}}<small>Early [[Miocene]] – [[Holocene]], possible late [[Oligocene]] record<ref name=Noriphoca>{{Cite journal|author1=Leonard Dewaele |author2=Olivier Lambert |author3=Stephen Louwye |year=2018 |title=A critical revision of the fossil record, stratigraphy and diversity of the Neogene seal genus ''Monotherium'' (Carnivora, Phocidae) |journal=Royal Society Open Science |volume=5 |issue=5 |article-number=171669 |doi=10.1098/rsos.171669 |doi-access=free|pmid=29892365 |pmc=5990722 |bibcode=2018RSOS....571669D }}</ref></small>
| taxon = Phocidae
| taxon = Phocidae
| display_parents = 2
| authority = [[John Edward Gray|Gray]], 1821
| authority = [[John Edward Gray|Gray]], 1821
| type_genus = ''[[Phoca]]''
| type_genus = ''[[Phoca]]''
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*[[Monachinae]]
*[[Monachinae]]
*[[Phocinae]]
*[[Phocinae]]
| range_map = File:Phocidae distribution.png
| range_map_caption = Phocidae distribution
}}
}}


The '''earless seals''', '''phocids''', or '''true seals''' are one of the three main groups of [[mammal]]s within the seal lineage, [[Pinniped]]ia. All true seals are members of the family '''Phocidae''' ({{IPAc-en|ˈ|f|oʊ|s|ᵻ|d|iː}}). They are sometimes called '''crawling seals''' to distinguish them from the [[fur seal]]s and [[sea lion]]s of the family [[Eared seal|Otariidae]]. Seals live in the [[ocean]]s of both hemispheres and, with the exception of the more [[tropical]] [[monk seal]]s, are mostly confined to [[Polar region|polar]], subpolar, and [[temperate]] climates.  The [[Baikal seal]] is the only species of exclusively [[freshwater seal]].
The '''earless seals''', also known as '''phocids''' or '''true seals''', are one of the three main groups of [[mammal]]s within the seal lineage, [[Pinniped]]ia. All true seals are members of the family '''Phocidae''' ({{IPAc-en|ˈ|f|oʊ|s|ᵻ|d|iː}}). They are sometimes called '''crawling seals''' to distinguish them from the [[fur seal]]s and [[sea lion]]s of the family [[Eared seal|Otariidae]]. Seals live in the [[ocean]]s of both hemispheres and, with the exception of the more [[tropical]] [[monk seal]]s, are mostly confined to [[Polar region|polar]], subpolar, and [[temperate]] climates.  The [[Baikal seal]] is the only species of exclusively [[freshwater seal]].


==Taxonomy and evolution==
==Taxonomy and evolution==
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[[File:Cranio Pliophoca etrusca, Orciano.JPG|thumb|Fossil ''[[Pliophoca]]'' skull]]
[[File:Cranio Pliophoca etrusca, Orciano.JPG|thumb|Fossil ''[[Pliophoca]]'' skull]]


The earliest known fossil earless seal is ''[[Noriphoca]] gaudini'' from the late [[Oligocene]] or earliest [[Miocene]] ([[Aquitanian (stage)|Aquitanian]]) of [[Italy]].<ref name=Noriphoca /> Other early fossil phocids date from the mid-Miocene, 15 million years ago in the north Atlantic.<ref name=Noriphoca /><ref>{{Cite journal|last1=Dewaele|first1=Leonard|last2=Lambert|first2=Olivier|last3=Louwye|first3=Stephen|date=2017-02-21|title=On ''Prophoca'' and ''Leptophoca'' (Pinnipedia, Phocidae) from the Miocene of the North Atlantic realm: redescription, phylogenetic affinities and paleobiogeographic implications|journal=PeerJ|language=en|volume=5|pages=e3024|doi=10.7717/peerj.3024|pmid=28243538|doi-access=free|pmc=5322758}}</ref> Until recently, many researchers believed that phocids evolved separately from [[otariids]] and [[Walrus|odobenids]]; and that they evolved from [[otter]]-like animals, such as ''[[Potamotherium]]'', which inhabited European freshwater lakes. Recent evidence strongly suggests a monophyletic origin for all pinnipeds from a single ancestor, possibly ''[[Enaliarctos]]'', most closely related to the [[Mustelidae|mustelids]] and [[bear]]s.<ref>{{Cite journal|last1=Paterson|first1=Ryan S.|last2=Rybczynski|first2=Natalia|last3=Kohno|first3=Naoki|last4=Maddin|first4=Hillary C.|date=2020|title=A Total Evidence Phylogenetic Analysis of Pinniped Phylogeny and the Possibility of Parallel Evolution Within a Monophyletic Framework|journal=Frontiers in Ecology and Evolution|language=en|volume=7|doi=10.3389/fevo.2019.00457|doi-access=free}}</ref>
The earliest known [[fossil]] earless seal is ''[[Noriphoca]] gaudini'' from the late [[Oligocene]] or earliest [[Miocene]] ([[Aquitanian (stage)|Aquitanian]]) of [[Italy]].<ref name=Noriphoca /> Other early fossil phocids date from the mid-Miocene, 15 million years ago in the north Atlantic.<ref name=Noriphoca /><ref>{{Cite journal|last1=Dewaele|first1=Leonard|last2=Lambert|first2=Olivier|last3=Louwye|first3=Stephen|date=2017-02-21|title=On ''Prophoca'' and ''Leptophoca'' (Pinnipedia, Phocidae) from the Miocene of the North Atlantic realm: redescription, phylogenetic affinities and paleobiogeographic implications|journal=PeerJ|language=en|volume=5|article-number=e3024|doi=10.7717/peerj.3024|pmid=28243538|doi-access=free|pmc=5322758}}</ref> Until recently, many researchers believed that phocids evolved separately from [[otariids]] and [[Walrus|odobenids]]; and that they evolved from [[otter]]-like animals, such as ''[[Potamotherium]]'', which inhabited European freshwater lakes. Recent evidence strongly suggests a monophyletic origin for all pinnipeds from a single ancestor, possibly ''[[Enaliarctos]]'', most closely related to the [[Mustelidae|mustelids]] and [[bear]]s.<ref>{{Cite journal|last1=Paterson|first1=Ryan S.|last2=Rybczynski|first2=Natalia|last3=Kohno|first3=Naoki|last4=Maddin|first4=Hillary C.|date=2020|title=A Total Evidence Phylogenetic Analysis of Pinniped Phylogeny and the Possibility of Parallel Evolution Within a Monophyletic Framework|journal=Frontiers in Ecology and Evolution|language=en|volume=7|article-number=457 |doi=10.3389/fevo.2019.00457|doi-access=free |bibcode=2020FrEEv...7..457P }}</ref>


[[Monk seal]]s and [[elephant seal]]s were previously believed to have first entered the Pacific through the open straits between North and South America,<ref name="Fulton-2010" /> with the Antarctic true seals either using the same route or travelled down the west coast of Africa.<ref>{{cite book |author1=Savage, RJG |author2= Long, MR |name-list-style=amp|year=1986 |title= Mammal Evolution: an illustrated guide|url=https://archive.org/details/mammalevolutioni0000sava |url-access=registration |publisher= Facts on File|location=New York|pages= [https://archive.org/details/mammalevolutioni0000sava/page/94 94–95]|isbn= 978-0-8160-1194-0}}</ref> It is now thought that the [[monk seal]]s, [[elephant seal]]s, and [[Lobodontini|Antarctic seals]] all evolved in the southern hemisphere, and likely dispersed to their current distributions from more southern latitudes.<ref>{{Cite journal|last1=Rule|first1=James P.|last2=Adams|first2=Justin W.|last3=Marx|first3=Felix G.|last4=Evans|first4=Alistair R.|last5=Tennyson|first5=Alan J. D.|last6=Scofield|first6=R. Paul|last7=Fitzgerald|first7=Erich M. G.|date=2020-11-11|title=First monk seal from the Southern Hemisphere rewrites the evolutionary history of true seals|journal=Proceedings of the Royal Society B: Biological Sciences|volume=287|issue=1938|pages=20202318|doi=10.1098/rspb.2020.2318|pmid=33171079|pmc=7735288|doi-access=free}}</ref>
[[Monk seal]]s and [[elephant seal]]s were previously believed to have first entered the Pacific through the open straits between North and South America,<ref name="Fulton-2010" /> with the Antarctic true seals either using the same route or travelled down the west coast of Africa.<ref>{{cite book |author1=Savage, RJG |author2= Long, MR |name-list-style=amp|year=1986 |title= Mammal Evolution: an illustrated guide|url=https://archive.org/details/mammalevolutioni0000sava |url-access=registration |publisher= Facts on File|location=New York|pages= [https://archive.org/details/mammalevolutioni0000sava/page/94 94–95]|isbn= 978-0-8160-1194-0}}</ref> It is now thought that the monk seals, elephant seals, and [[Lobodontini|Antarctic seals]] all evolved in the southern hemisphere, and likely dispersed to their current distributions from more southern latitudes.<ref>{{Cite journal|last1=Rule|first1=James P.|last2=Adams|first2=Justin W.|last3=Marx|first3=Felix G.|last4=Evans|first4=Alistair R.|last5=Tennyson|first5=Alan J. D.|last6=Scofield|first6=R. Paul|last7=Fitzgerald|first7=Erich M. G.|date=2020-11-11|title=First monk seal from the Southern Hemisphere rewrites the evolutionary history of true seals|journal=Proceedings of the Royal Society B: Biological Sciences|volume=287|issue=1938|article-number=20202318|doi=10.1098/rspb.2020.2318|pmid=33171079|pmc=7735288|doi-access=free}}</ref>


===Taxonomy===
===Taxonomy===
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       |2={{clade
       |2={{clade
         |1={{clade
         |1={{clade
             |label1=Lobodontini
             |label1=[[Lobodontini]]
             |1={{clade
             |1={{clade
               |1={{clade
               |1={{clade
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               |2=[[Ross seal]]<!-- Ommatophoca rossii -->
               |2=[[Ross seal]]<!-- Ommatophoca rossii -->
               }}
               }}
             |label2=Miroungini|sublabel2=(elephant seals)
             |label2=[[Miroungini]]|sublabel2=(elephant seals)
             |2={{clade
             |2={{clade
               |1=[[Southern elephant seal]]<!-- Mirounga leonina -->
               |1=[[Southern elephant seal]]<!-- Mirounga leonina -->
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}}
}}


In the 1980s and 1990s, morphological [[phylogenetics|phylogenetic]] analysis of the phocids led to new conclusions about the interrelatedness of the various genera. More recent molecular phylogenetic analyses have confirmed the [[monophyly]] of the two phocid subfamilies ([[Phocinae]] and Monachinae).<ref>{{Cite journal|last1=Árnason|first1=Úlfur|last2=Bodin|first2=Kristina|last3=Gullberg|first3=Anette|last4=Ledje|first4=Christina|last5=Suzette|first5=Mouchaty|date=1995|title=A molecular view of pinniped relationships with particular emphasis on the true seals|journal=Journal of Molecular Evolution|volume=40 |issue=1 |pages=78–85|doi=10.1007/BF00166598|pmid=7714914 |bibcode=1995JMolE..40...78A |s2cid=7537924}}</ref><ref>{{Cite journal|last1=Arnason |first1=Ulfur |last2=Gullberg |first2=Anette |last3=Janke|first3=Axel |last4=Kullberg|first4=Morgan |last5=Lehman |first5=Niles |last6=Petrov |first6=Evgeny A.|last7=Väinölä|first7=Risto|date=2006-11-01 |title=Pinniped phylogeny and a new hypothesis for their origin and dispersal|journal=Molecular Phylogenetics and Evolution |volume=41|issue=2 |pages=345–354|doi=10.1016/j.ympev.2006.05.022 |pmid=16815048|bibcode=2006MolPE..41..345A }}</ref><ref>{{Cite journal|last1=Fulton|first1=Tara Lynn|last2=Strobeck|first2=Curtis |date=2010|title=Multiple markers and multiple individuals refine true seal phylogeny and bring molecules and morphology back in line |journal=Proceedings of the Royal Society B: Biological Sciences  |volume=277 |issue=1684 |pages=1065–1070 |doi=10.1098/rspb.2009.1783|pmc=2842760|pmid=19939841}}</ref><ref name="Fulton-2010">{{Cite journal |last1=Fulton |first1=Tara L. |last2=Strobeck|first2=Curtis |date=2010|title=Multiple fossil calibrations, nuclear loci and mitochondrial genomes provide new insight into biogeography and divergence timing for true seals (Phocidae, Pinnipedia) |journal=Journal of Biogeography |volume=37|issue=5 |pages=814–829 |doi=10.1111/j.1365-2699.2010.02271.x|bibcode=2010JBiog..37..814F |s2cid=59436229 }}</ref> The Monachinae (known as the "southern" seals), is composed of three tribes; the Lobodontini, Miroungini, and Monachini. The four [[Antarctic]] genera ''[[leopard seal|Hydrurga]]'', ''[[Weddell seal|Leptonychotes]]'', ''[[crabeater seal|Lobodon]]'', and ''[[Ross seal|Ommatophoca]]'' are part of the [[tribe (biology)|tribe]] [[Lobodontini]]. Tribe Miroungini is composed of the [[elephant seal]]s. The [[Monk seal]]s (''[[Mediterranean monk seal|Monachus]]'' and ''[[Neomonachus]]'') are all part of the tribe Monachini.<ref>{{Cite journal |last1=Scheel |first1=Dirk-Martin|last2=Slater|first2=Graham J.|last3=Kolokotronis|first3=Sergios-Orestis |last4=Potter |first4=Charles W.|last5=Rotstein|first5=David S.|last6=Tsangaras|first6=Kyriakos |last7=Greenwood|first7=Alex D.|last8=Helgen|first8=Kristofer M.|date=2014|title=Biogeography and taxonomy of extinct and endangered monk seals illuminated by ancient DNA and skull morphology |journal=ZooKeys|issue=409 |pages=1–33|doi=10.3897/zookeys.409.6244|pmc=4042687|pmid=24899841|doi-access=free|bibcode=2014ZooK..409....1S }}</ref> Likewise, subfamily Phocinae (the "northern" seals) also includes three tribes; Erignathini (''[[bearded seal|Erignathus]])'', Cystophorini (''[[hooded seal|Cystophora)]]'', and [[Phocini]] (all other phocines). More recently, five species have been split off from ''Phoca'', forming three additional genera.<ref>{{Cite journal|last1=Berta|first1=Annalisa |last2=Churchill|first2=Morgan|date=2012 |title=Pinniped taxonomy: review of currently recognized species and subspecies, and evidence used for their description|journal=Mammal Review |volume=42 |issue=3|pages=207–234 |doi=10.1111/j.1365-2907.2011.00193.x|bibcode=2012MamRv..42..207B }}</ref>
In the 1980s and 1990s, morphological [[phylogenetics|phylogenetic]] analysis of the phocids led to new conclusions about the interrelatedness of the various genera. More recent molecular phylogenetic analyses have confirmed the [[monophyly]] of the two phocid subfamilies ([[Phocinae]] and Monachinae).<ref>{{Cite journal|last1=Árnason|first1=Úlfur|last2=Bodin|first2=Kristina|last3=Gullberg|first3=Anette|last4=Ledje|first4=Christina|last5=Suzette|first5=Mouchaty|date=1995|title=A molecular view of pinniped relationships with particular emphasis on the true seals|journal=Journal of Molecular Evolution|volume=40 |issue=1 |pages=78–85|doi=10.1007/BF00166598|pmid=7714914 |bibcode=1995JMolE..40...78A |s2cid=7537924}}</ref><ref>{{Cite journal|last1=Arnason |first1=Ulfur |last2=Gullberg |first2=Anette |last3=Janke|first3=Axel |last4=Kullberg|first4=Morgan |last5=Lehman |first5=Niles |last6=Petrov |first6=Evgeny A.|last7=Väinölä|first7=Risto|date=2006-11-01 |title=Pinniped phylogeny and a new hypothesis for their origin and dispersal|journal=Molecular Phylogenetics and Evolution |volume=41|issue=2 |pages=345–354|doi=10.1016/j.ympev.2006.05.022 |pmid=16815048|bibcode=2006MolPE..41..345A }}</ref><ref>{{Cite journal|last1=Fulton|first1=Tara Lynn|last2=Strobeck|first2=Curtis |date=2010|title=Multiple markers and multiple individuals refine true seal phylogeny and bring molecules and morphology back in line |journal=Proceedings of the Royal Society B: Biological Sciences  |volume=277 |issue=1684 |pages=1065–1070 |doi=10.1098/rspb.2009.1783|pmc=2842760|pmid=19939841 |bibcode=2010PBioS.277.1065F }}</ref><ref name="Fulton-2010">{{Cite journal |last1=Fulton |first1=Tara L. |last2=Strobeck|first2=Curtis |date=2010|title=Multiple fossil calibrations, nuclear loci and mitochondrial genomes provide new insight into biogeography and divergence timing for true seals (Phocidae, Pinnipedia) |journal=Journal of Biogeography |volume=37|issue=5 |pages=814–829 |doi=10.1111/j.1365-2699.2010.02271.x|bibcode=2010JBiog..37..814F |s2cid=59436229 }}</ref> The Monachinae (known as the "southern" seals), is composed of three tribes; the Lobodontini, Miroungini, and Monachini. The four [[Antarctic]] genera ''[[leopard seal|Hydrurga]]'', ''[[Weddell seal|Leptonychotes]]'', ''[[crabeater seal|Lobodon]]'', and ''[[Ross seal|Ommatophoca]]'' are part of the [[tribe (biology)|tribe]] [[Lobodontini]]. Tribe Miroungini is composed of the [[elephant seal]]s. The [[Monk seal]]s (''[[Mediterranean monk seal|Monachus]]'' and ''[[Neomonachus]]'') are all part of the tribe Monachini.<ref>{{Cite journal |last1=Scheel |first1=Dirk-Martin|last2=Slater|first2=Graham J.|last3=Kolokotronis|first3=Sergios-Orestis |last4=Potter |first4=Charles W.|last5=Rotstein|first5=David S.|last6=Tsangaras|first6=Kyriakos |last7=Greenwood|first7=Alex D.|last8=Helgen|first8=Kristofer M.|date=2014|title=Biogeography and taxonomy of extinct and endangered monk seals illuminated by ancient DNA and skull morphology |journal=ZooKeys|issue=409 |pages=1–33|doi=10.3897/zookeys.409.6244|pmc=4042687|pmid=24899841|doi-access=free|bibcode=2014ZooK..409....1S }}</ref> Likewise, subfamily Phocinae (the "northern" seals) also includes three tribes; Erignathini (''[[bearded seal|Erignathus]])'', Cystophorini (''[[hooded seal|Cystophora)]]'', and [[Phocini]] (all other phocines). More recently, five species have been split off from ''Phoca'', forming three additional genera.<ref>{{Cite journal|last1=Berta|first1=Annalisa |last2=Churchill|first2=Morgan|date=2012 |title=Pinniped taxonomy: review of currently recognized species and subspecies, and evidence used for their description|journal=Mammal Review |volume=42 |issue=3|pages=207–234 |doi=10.1111/j.1365-2907.2011.00193.x|bibcode=2012MamRv..42..207B }}</ref>


Alternatively the three monachine tribes have been evaluated to familiar status, which elephant seals and the Antarctic seals are more closely related to the phocines.<ref name="Bonner1994">{{cite book | last1 = Bonner | first1 = N. | year = 1994| title = Seals and Sea Lions of the World | publisher = Blandford |location= United Kingdom | pages = 1–224 |isbn = 9780816057177}}</ref>
Alternatively the three monachine tribes have been evaluated to familiar status, which elephant seals and the Antarctic seals are more closely related to the phocines.<ref name="Bonner1994">{{cite book | last1 = Bonner | first1 = N. | year = 1994| title = Seals and Sea Lions of the World | publisher = Blandford |location= United Kingdom | pages = 1–224 |isbn = 978-0-8160-5717-7}}</ref>
{{Clear}}
{{Clear}}


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! Subfamily!! Tribe !! Image !! Genus !! species
! Subfamily!! Tribe !! Image !! Genus !! species
|-
|-
! rowspan="7"  style="text-align:center;"| '''Subfamily [[Monachinae]]'''
! rowspan="7"  style="text-align:center;"| Subfamily [[Monachinae]]
! rowspan="2"  style="text-align:center;"| '''Tribe [[Monachini]]'''
! rowspan="2"  style="text-align:center;"| Tribe [[Monachini]]
|[[File:Monachus monachus.jpg|175px]] ||''[[Monachus]]'' <small>Fleming, 1822</small> ||  
|[[File:Monachus monachus.jpg|175px]] ||''[[Monachus]]'' <small>Fleming, 1822</small> ||  
* [[Mediterranean monk seal]], ''Monachus monachus''
* [[Mediterranean monk seal]], ''Monachus monachus''
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|[[File:Monachus schauinslandi.jpg|175px]] ||''[[Neomonachus]]'' <small>Slater & Helgen, 2014</small> ||  
|[[File:Monachus schauinslandi.jpg|175px]] ||''[[Neomonachus]]'' <small>Slater & Helgen, 2014</small> ||  
*[[Hawaiian monk seal]], ''Neomonachus schauinslandi''
*[[Hawaiian monk seal]], ''Neomonachus schauinslandi''
* †[[Caribbean monk seal]], ''Neomonachus  tropicalis'' (probably extinct around 1952)
|-
|-
! rowspan="1"  style="text-align:center;"| '''Tribe Miroungini'''
! rowspan="1"  style="text-align:center;"| Tribe Miroungini
|[[File:Mirounga angustirostris, Point Reyes (cropped).jpg|175px]] ||''[[Mirounga]]'' <small>Gray, 1827</small> ||  
|[[File:Mirounga angustirostris, Point Reyes (cropped).jpg|175px]] ||''[[Mirounga]]'' <small>Gray, 1827</small> ||  
* [[Northern elephant seal]], ''Mirounga angustirostris''
* [[Northern elephant seal]], ''Mirounga angustirostris''
* [[Southern elephant seal]], ''Mirounga leonina''
* [[Southern elephant seal]], ''Mirounga leonina''
|-
|-
! rowspan="4"  style="text-align:center;"| '''Tribe [[Lobodontini]]'''
! rowspan="4"  style="text-align:center;"| Tribe [[Lobodontini]]
|[[File:Ross-seal.jpg|175px]] ||''[[Ommatophoca]]'' <small>Gray, 1844</small> ||  
|[[File:Ross-seal.jpg|175px]] ||''[[Ommatophoca]]'' <small>Gray, 1844</small> ||  
* [[Ross seal]], ''Ommatophoca rossi''
* [[Ross seal]], ''Ommatophoca rossi''
Line 142: Line 144:
* [[Weddell seal]], ''Leptonychotes weddellii''
* [[Weddell seal]], ''Leptonychotes weddellii''
|-
|-
! rowspan="7"  style="text-align:center;"| '''Subfamily [[Phocinae]]'''
! rowspan="7"  style="text-align:center;"| Subfamily [[Phocinae]]
! rowspan="1"  style="text-align:center;"| '''Tribe Cystophorini'''
! rowspan="1"  style="text-align:center;"| Tribe Cystophorini
|[[File:2016-klappmützemuseumkoenig.jpg|175px]] ||''[[Cystophora (mammal)|Cystophora]]'' <small>Nilsson, 1820</small> ||  
|[[File:2016-klappmützemuseumkoenig.jpg|175px]] ||''[[Cystophora (mammal)|Cystophora]]'' <small>Nilsson, 1820</small> ||  
* [[Hooded seal]], ''Cystophora cristata''
* [[Hooded seal]], ''Cystophora cristata''
|-
|-
! rowspan="1"  style="text-align:center;"| '''Tribe Erignathini'''
! rowspan="1"  style="text-align:center;"| Tribe Erignathini
|[[File:Bearded Seal at Svalbard (cropped).jpg|175px]] ||''[[Erignathus]]'' <small>Gill, 1866</small> ||  
|[[File:Bearded Seal at Svalbard (cropped).jpg|175px]] ||''[[Erignathus]]'' <small>Gill, 1866</small> ||  
* [[Bearded seal]], ''Erignathus barbatus''
* [[Bearded seal]], ''Erignathus barbatus''
|-
|-
! rowspan="5"  style="text-align:center;"| '''Tribe Phocini'''
! rowspan="5"  style="text-align:center;"| Tribe Phocini
|[[File:Seehund2cele4.jpg|175px]] ||''[[Phoca]]'' <small>Linnaeus, 1758</small> ||  
|[[File:Seehund2cele4.jpg|175px]] ||''[[Phoca]]'' <small>Linnaeus, 1758</small> ||  
* [[Harbor seal]] or common seal, ''Phoca vitulina''
* [[Harbor seal]] or common seal, ''Phoca vitulina''
Line 160: Line 162:
* [[Baikal seal]], ''Pusa sibirica'' (formerly ''Phoca sibirica'')
* [[Baikal seal]], ''Pusa sibirica'' (formerly ''Phoca sibirica'')
* [[Caspian seal]], ''Pusa caspica'' (formerly ''Phoca caspica'')
* [[Caspian seal]], ''Pusa caspica'' (formerly ''Phoca caspica'')
* [[Saimaa ringed seal]], ''Pusa saimensis'' (formerly ''Pusa hispida saimensis'')
|-
|-
|[[File:Harp seal at False Cape (cut).jpg|175px]] ||''[[Pagophilus]]'' <small>Gray, 1844</small> ||  
|[[File:Harp seal at False Cape (cut).jpg|175px]] ||''[[Pagophilus]]'' <small>Gray, 1844</small> ||  
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[[File:Phoca vitulina 02 MWNH 1464.JPG|thumb|left|[[Harbor seal]] skull (''Phoca vitulina'')]]
[[File:Phoca vitulina 02 MWNH 1464.JPG|thumb|left|[[Harbor seal]] skull (''Phoca vitulina'')]]


Adult phocids vary from {{convert|1.17|m|ft|abbr=on}} in length and {{convert|45|kg|lb|abbr=on}} in weight in the [[ringed seal]] to {{convert|5.8|m|ft|abbr=on}} and {{convert|4000|kg|lb|abbr=on}} in the [[southern elephant seal]], which is the largest member of the order [[Carnivora]]. Phocids have fewer teeth than land-based members of the [[Carnivora]], although they retain powerful [[canine tooth|canines]]. Some species lack [[Molar (tooth)|molar]]s altogether. The [[dentition|dental formula]] is:
Adult phocids vary from {{convert|1.17|m|ft|abbr=on}} in length and {{convert|45|kg|lb|abbr=on}} in weight in the [[ringed seal]] to {{convert|5.8|m|ft|abbr=on}} and {{convert|4000|kg|lb|abbr=on}} in the [[southern elephant seal]], the largest member of the order [[Carnivora]]. Phocids have fewer teeth than land-based members of the Carnivora, although they retain powerful [[canine tooth|canines]]. Some species lack [[Molar (tooth)|molar]]s altogether. The [[dentition|dental formula]] is:
{{DentalFormula|upper=2–3.1.4.0–2|lower=1–2.1.4.0–2}}
{{DentalFormula|upper=2–3.1.4.0–2|lower=1–2.1.4.0–2}}


While otariids are known for speed and maneuverability, phocids are known for efficient, economical movement. This allows most phocids to forage far from land to exploit prey resources, while otariids are tied to rich [[upwelling]] zones close to breeding sites. Phocids swim by sideways movements of their bodies, using their hind flippers to fullest effect.<ref name=EoM>{{cite book|editor= Macdonald, D.|author= McLaren, Ian|year= 1984|title= The Encyclopedia of Mammals|publisher= Facts on File|location= New York|pages= [https://archive.org/details/encyclopediaofma00mals_0/page/270 270–275]|isbn= 978-0-87196-871-5|url-access= registration|url= https://archive.org/details/encyclopediaofma00mals_0/page/270}}</ref> Their fore flippers are used primarily for steering, while their hind flippers are bound to the [[pelvis]] in such a way that they cannot bring them under their bodies to walk on them. They are more streamlined than fur seals and sea lions, so they can swim more effectively over long distances. However, because they cannot turn their hind flippers downward, they are very clumsy on land, having to wriggle with their front flippers and abdominal [[muscle]]s.
While otariids are known for speed and maneuverability, phocids are known for efficient, economical movement. This allows most phocids to forage far from land to exploit prey resources, while otariids are tied to rich [[upwelling]] zones close to breeding sites. Phocids swim in a sideways motion with their bodies;<ref name=EoM>{{cite book|editor= Macdonald, D.|author= McLaren, Ian|year= 1984|title= The Encyclopedia of Mammals|publisher= Facts on File|location= New York|pages= [https://archive.org/details/encyclopediaofma00mals_0/page/270 270–275]|isbn= 978-0-87196-871-5|url-access= registration|url= https://archive.org/details/encyclopediaofma00mals_0/page/270}}</ref> their fore flippers are primarily used for steering, whereas their hind flippers are used for underwater propulsion.<ref>{{Cite web |title=Harbor Seal (Phoca vitulina)  |url=https://www.adfg.alaska.gov/index.cfm?adfg=harborseal.printerfriendly |access-date=2026-02-06 |website=www.adfg.alaska.gov}}</ref> While phocids' streamlined bodies make them better long-distance swimmers than otariids, unlike [[fur seals]], their hind flippers are bound to the [[pelvis]] and unable to be rotated forward for walking. As a result, they are clumsy on land, having to wriggle with their front flippers and abdominal [[muscle]]s.


[[File:Seal kidney-- FMVZ USP-08.jpg|thumb|Seal kidney]]
[[File:Seal kidney-- FMVZ USP-08.jpg|thumb|Seal kidney]]


Phocid respiratory and circulatory systems are adapted to allow diving to considerable depths, and they can spend a long time underwater between breaths. Air is forced from the [[lung]]s during a dive and into the upper respiratory passages, where gases cannot easily be absorbed into the bloodstream. This helps protect the seal from [[Decompression sickness|the bends]]. The [[middle ear]] is also lined with blood sinuses that inflate during diving, helping to maintain a constant pressure.<ref name=EoM/>
Phocid respiratory and circulatory systems are adapted to facilitate diving into considerable depths, allowing them to spend long periods of time underwater. When a seal dives, air is forced from the [[lung]]s and into the upper respiratory passages, where gases cannot easily be absorbed into the bloodstream, protecting it from [[Decompression sickness|the bends]]. The [[middle ear]] is also lined with blood sinuses that inflate during diving, helping to maintain a constant pressure.<ref name=EoM/>


Phocids are more specialized for [[Aquatic animal|aquatic]] life than otariids. They lack external ears and have sleek, streamlined bodies. Retractable [[nipple]]s, internal [[testicle]]s,<ref name="PerrinWürsig2009">{{cite book|author1=Perrin, William F. |author2=Würsig, Bernd |author3= Thewissen, J.G.M.|title=Encyclopedia of Marine Mammals|url=https://books.google.com/books?id=2rkHQpToi9sC&q=phocid+OR+phocidae|date=2009|publisher=Academic Press|isbn=978-0-08-091993-5}}</ref> and an internal [[penile sheath]] provide further streamlining. A smooth layer of [[blubber]] lies underneath the skin. Phocids are able to divert [[blood]] flow to this layer to help control their temperatures.<ref>{{Cite journal|last1=Favilla|first1=Arina B.|last2=Costa|first2=Daniel P.|date=2020-09-11|title=Thermoregulatory Strategies of Diving Air-Breathing Marine Vertebrates: A Review|journal=Frontiers in Ecology and Evolution|volume=8|pages=555509|doi=10.3389/fevo.2020.555509|issn=2296-701X|doi-access=free}}</ref>
Phocid bodies are more specialized for [[Aquatic animal|aquatic]] life than otariids, as supported by the presence of ear holes (as opposed to external ears in fur seals), retractable [[nipple]]s, internal [[testicle]]s,<ref name="PerrinWürsig2009">{{cite book|author1=Perrin, William F. |author2=Würsig, Bernd |author3= Thewissen, J.G.M.|title=Encyclopedia of Marine Mammals|url=https://books.google.com/books?id=2rkHQpToi9sC&q=phocid+OR+phocidae|date=2009|publisher=Academic Press|isbn=978-0-08-091993-5}}</ref> and an internal [[penile sheath]]. Phocids are able to divert [[blood]] flow to a smooth layer of [[blubber]] underneath their skin to help regulate body temperature.<ref>{{Cite journal|last1=Favilla|first1=Arina B.|last2=Costa|first2=Daniel P.|date=2020-09-11|title=Thermoregulatory Strategies of Diving Air-Breathing Marine Vertebrates: A Review|journal=Frontiers in Ecology and Evolution|volume=8|article-number=555509|doi=10.3389/fevo.2020.555509|issn=2296-701X|doi-access=free |bibcode=2020FrEEv...855509F }}</ref>


===Communication===
===Communication===
Unlike otariids, phocine seals do not communicate by "barking". Instead, they communicate by slapping the water and grunting, with a few species have been documented to clap at each other underwater.<ref>{{cite web|last1=Hocking|first1=David|last2=Burnville|first2=Ben|last3=Marx|first3=Felix Georg|url=https://www.ncl.ac.uk/press/articles/archive/2020/02/conversationsealsclapping/|title=Comment: Grey seals discovered clapping underwater to communicate|work=[[The Conversation (website)|The Conversation]]|via=[[Newcastle University]]|date=February 3, 2020|accessdate=April 15, 2025}}</ref> One study published in ''[[Animal Behaviour (journal)|Animal Behaviour]]'' found that seals use rhythmic [[percussive]] signalling (clapping) in both "agonistic interactions" and display behavior.<ref>{{cite journal |last1=Kocsis |first1=Kinga |last2=Duengen |first2=Diandra |last3=Jadoul |first3=Yannick |last4=Ravignani |first4=Andrea |title=Harbour seals use rhythmic percussive signalling in interaction and display |journal=[[Animal Behaviour (journal)|Animal Behaviour]] |date=January 2024 |volume=207 |pages=223–234 |doi=10.1016/j.anbehav.2023.09.014 |bibcode=2024AnBeh.207..223K }}</ref>
Unlike otariids, phocine seals do not communicate by "barking". Instead, they communicate by slapping the water and grunting, with a few species having been documented to clap at each other underwater.<ref>{{cite web|last1=Hocking|first1=David|last2=Burnville|first2=Ben|last3=Marx|first3=Felix Georg|url=https://www.ncl.ac.uk/press/articles/archive/2020/02/conversationsealsclapping/|title=Comment: Grey seals discovered clapping underwater to communicate|work=[[The Conversation (website)|The Conversation]]|via=[[Newcastle University]]|date=February 3, 2020|access-date=April 15, 2025}}</ref> One study published in ''[[Animal Behaviour (journal)|Animal Behaviour]]'' found that seals use rhythmic [[percussive]] signalling (clapping) in both "agonistic interactions" and display behavior.<ref>{{cite journal |last1=Kocsis |first1=Kinga |last2=Duengen |first2=Diandra |last3=Jadoul |first3=Yannick |last4=Ravignani |first4=Andrea |title=Harbour seals use rhythmic percussive signalling in interaction and display |journal=[[Animal Behaviour (journal)|Animal Behaviour]] |date=January 2024 |volume=207 |pages=223–234 |doi=10.1016/j.anbehav.2023.09.014 |bibcode=2024AnBeh.207..223K |url=https://pure.au.dk/portal/en/publications/71a58fc8-a077-4711-a11f-232490706e71 }}</ref>


Conversely, monachine seals are well known to vocalize: elephant seals often vocalize on land,{{Clarify|reason=What do the females and pups sound like?|date=July 2025}} with the bulls being well known for roaring to establish dominance and identifying themselves.<ref name="McCann 1981">{{cite journal |first=T. S. |last= McCann |year=1981 |title=Aggression and sexual activity of male Southern elephant seals, ''Mirounga leonina'' |journal=[[Journal of Zoology]] |volume=195 |issue=3 |pages=295–310 |doi=10.1111/j.1469-7998.1981.tb03467.x}}</ref> The [[Weddell seal#Vocalisation|Weddell]] and [[Leopard seal#Acoustic behavior|leopard seals]] are well known for their underwater singing.<ref>{{Cite journal|last=Terhune|first=John M.|date=2017-04-13|title=Through-ice communication by Weddell seals (Leptonychotes weddellii) is possible|journal=Polar Biology|volume=40|issue=10|pages=2133–2136|doi=10.1007/s00300-017-2124-1|s2cid=23069267|issn=0722-4060}}</ref><ref>{{Cite journal|last1=Green|first1=K.|last2=Burton|first2=H. R.|date=January 1988|title=Do Weddell seals sing?|journal=Polar Biology|volume=8|issue=3|pages=165–166|doi=10.1007/bf00443448|s2cid=46256980|issn=0722-4060}}</ref><ref>{{cite journal|author= Rogers TL |year=2014|title= Source levels of the underwater calls of a male leopard seal |journal= The Journal of the Acoustical Society of America|volume=136|issue=4|pages= 1495–1498|doi=10.1121/1.4895685|pmid=25324053|bibcode=2014ASAJ..136.1495R}}</ref><ref>{{Cite journal|last1=Rogers|first1=Tracey L.|last2=Cato|first2=Douglas H.|date=2002|title=Individual Variation in the Acoustic Behaviour of the Adult Male Leopard Seal, Hydrurga leptonyx|jstor=4535987|journal=Behaviour|volume=139|issue=10|pages=1267–1286|doi=10.1163/156853902321104154}}</ref>
Conversely, monachine seals are well known to vocalize: Elephant seals often vocalize on land,{{Clarify|reason=What do the females and pups sound like?|date=July 2025}} with the bulls being well known for roaring to establish dominance and identify themselves.<ref name="McCann 1981">{{cite journal |first=T. S. |last= McCann |year=1981 |title=Aggression and sexual activity of male Southern elephant seals, ''Mirounga leonina'' |journal=[[Journal of Zoology]] |volume=195 |issue=3 |pages=295–310 |doi=10.1111/j.1469-7998.1981.tb03467.x}}</ref> The [[Weddell seal#Vocalisation|Weddell]] and [[Leopard seal#Acoustic behavior|leopard seals]] are well known for their underwater singing.<ref>{{Cite journal|last=Terhune|first=John M.|date=2017-04-13|title=Through-ice communication by Weddell seals (Leptonychotes weddellii) is possible|journal=Polar Biology|volume=40|issue=10|pages=2133–2136|doi=10.1007/s00300-017-2124-1|bibcode=2017PoBio..40.2133T |s2cid=23069267|issn=0722-4060}}</ref><ref>{{Cite journal|last1=Green|first1=K.|last2=Burton|first2=H. R.|date=January 1988|title=Do Weddell seals sing?|journal=Polar Biology|volume=8|issue=3|pages=165–166|doi=10.1007/bf00443448|bibcode=1988PoBio...8..165G |s2cid=46256980|issn=0722-4060}}</ref><ref>{{cite journal|author= Rogers TL |year=2014|title= Source levels of the underwater calls of a male leopard seal |journal= The Journal of the Acoustical Society of America|volume=136|issue=4|pages= 1495–1498|doi=10.1121/1.4895685|pmid=25324053|bibcode=2014ASAJ..136.1495R}}</ref><ref>{{Cite journal|last1=Rogers|first1=Tracey L.|last2=Cato|first2=Douglas H.|date=2002|title=Individual Variation in the Acoustic Behaviour of the Adult Male Leopard Seal, Hydrurga leptonyx|jstor=4535987|journal=Behaviour|volume=139|issue=10|pages=1267–1286|doi=10.1163/156853902321104154 |bibcode=2002Behav.139.1267R }}</ref>


===Movements===
===Movements===
With short front flippers and because their rear flipper is unable to rotate, true seals cannot walk when out of the water like sea lions. As a result, they bounce themselves forward in a motion called ''[[wikt:galumphing|galumphing]]'';<ref>{{cite book|last=Dipper|first=Frances|title=[[Royal Society for the Protection of Birds|RSPB]] Spotlight: Seals|page=20|publisher=[[Bloomsbury Publishing|Bloomsbury Wildlife]]|location=[[London]]|isbn=978-1-4214-0305-2|date=2021}}</ref><ref>{{cite book|last=Derocher|first=Andrew E.|title=Polar Bears: A Complete Guide to Their Biology and Behavior|page=73|publisher=[[Johns Hopkins University Press]]|location=[[Baltimore]]|isbn=978-1-4214-0305-2|date=2012}}</ref> the polar explorer [[Edward Wilson (explorer)|Edward Wilson]] referred to the motion as ''lolloping''.<ref>{{cite book|last=Schmidt|first=Jeremy|title=Weddell Seals: Science, Life History, and Population Dynamics|page=59|publisher=Weddell Seal Science|isbn=978-1-881480-19-8|date=2023}}</ref>
With short front flippers and because their rear flipper is unable to rotate, true seals cannot walk when out of the water like sea lions. As a result, they bounce themselves forward in a motion called ''[[wikt:galumphing|galumphing]]'';<ref>{{cite book|last=Dipper|first=Frances|title=[[Royal Society for the Protection of Birds|RSPB]] Spotlight: Seals|page=20|publisher=[[Bloomsbury Publishing|Bloomsbury Wildlife]]|location=[[London]]|isbn=978-1-4214-0305-2|date=2021}}</ref><ref>{{cite book|last=Derocher|first=Andrew E.|title=Polar Bears: A Complete Guide to Their Biology and Behavior|page=73|publisher=[[Johns Hopkins University Press]]|location=[[Baltimore]]|isbn=978-1-4214-0305-2|date=2012}}</ref> the polar explorer [[Edward Wilson (explorer)|Edward Wilson]] referred to the motion as ''lolloping''.<ref>{{cite book|last=Schmidt|first=Jeremy|title=Weddell Seals: Science, Life History, and Population Dynamics|page=59|publisher=Weddell Seal Science|isbn=978-1-881480-19-8|date=2023}}</ref> It is also referred to as "worm-style" locomotion.<ref>{{Cite journal |last1=Esteban |first1=Juan Miguel |last2=Martín-Serra |first2=Alberto |last3=Pérez-Ramos |first3=Alejandro |last4=Rybczynski |first4=Natalia |last5=Pastor |first5=Francisco J. |last6=Figueirido |first6=Borja |date=2023 |title=Investigating the land-to-sea transition in carnivorans from the evolution of sacrum morphology in pinnipeds |url=https://link.springer.com/10.1007/s10914-023-09650-y |journal=Journal of Mammalian Evolution |language=en |volume=30 |issue=2 |pages=341–362 |doi=10.1007/s10914-023-09650-y |issn=1064-7554|hdl=10630/26300 |hdl-access=free }}</ref>


===Reproduction===
===Reproduction===
[[File:Earless seal (Puerto Madryn, Argentina).jpg|thumb|left|Southern elephant seals in Argentina|alt=Photo of seven adult and juvenile southern elephant seals packed closely on beach]]
[[File:Earless seal (Puerto Madryn, Argentina).jpg|thumb|left|Southern elephant seals in Argentina|alt=Photo of seven adult and juvenile southern elephant seals packed closely on beach]]
[[File:Antarctica_2013_Journey_to_the_Crystal_Desert_(8369569335).jpg|thumb|[[Weddell Seal]] in Antarctica]]
[[File:Pusa hispida saimensis ca 1956.jpg|thumb|Living only in [[Lake Saimaa]], [[Finland]], [[Saimaa ringed seal]]s, a subspecies of [[ringed seal]], are among the most [[Endangered species|endangered]] seals in the world, having a total population of only about 400 individuals.<ref>{{cite web |title= Saimaa Ringed Seal |url= https://wwf.fi/en/saimaaringedseal/  |access-date=22 December 2018}}</ref>]]
[[File:Pusa hispida saimensis ca 1956.jpg|thumb|Living only in [[Lake Saimaa]], [[Finland]], [[Saimaa ringed seal]]s, a subspecies of [[ringed seal]], are among the most [[Endangered species|endangered]] seals in the world, having a total population of only about 400 individuals.<ref>{{cite web |title= Saimaa Ringed Seal |url= https://wwf.fi/en/saimaaringedseal/  |access-date=22 December 2018}}</ref>]]
<!--[[File:Zwei junge Seehunde am Strand.jpg|thumb|[[Paul de Vos]]:Two young seals on a beach]]-->
<!--[[File:Zwei junge Seehunde am Strand.jpg|thumb|[[Paul de Vos]]:Two young seals on a beach]]-->


Phocids spend most of their time at sea, although they return to land or pack ice to breed and give birth. Pregnant females spend long periods foraging at sea, building up fat reserves, and then return to the breeding site to use their stored energy to nurse pups. However, the common seal displays a reproductive strategy similar to that used by [[Eared seal|otariids]], in which the mother makes short foraging trips between nursing bouts.{{citation needed|date=April 2025}}
Phocids spend most of their time at sea, although they return to land or pack ice to breed and give birth. Pregnant females spend long periods foraging at sea, building up fat reserves, and then return to the breeding site to use their stored energy to nurse pups<ref>{{Cite journal |last1=Sauvé |first1=Caroline C. |last2=Van de Walle |first2=Joanie |last3=Hammill |first3=Mike O. |last4=Arnould |first4=John P. Y. |last5=Beauplet |first5=Gwénaël |date=2014 |title=Stomach temperature records reveal nursing behaviour and transition to solid food consumption in an unweaned mammal, the harbour seal pup (Phoca vitulina) |journal=PLOS ONE |volume=9 |issue=2 |article-number=e90329 |doi=10.1371/journal.pone.0090329 |doi-access=free |issn=1932-6203 |pmc=3936010 |pmid=24587327 |bibcode=2014PLoSO...990329S }}</ref><ref>{{Cite web |date=2023-10-30 |title=Grey seal pup season {{!}} Cumbria Wildlife Trust |url=https://www.cumbriawildlifetrust.org.uk/blog/grey-seal-pup-season |access-date=2026-04-24 |website=www.cumbriawildlifetrust.org.uk |language=en}}</ref>. However, the common seal displays a reproductive strategy similar to that used by [[Eared seal|otariids]], in which the mother makes short foraging trips between nursing bouts.{{citation needed|date=April 2025}}


Because a phocid mother's feeding grounds are often hundreds of kilometers from the breeding site, she must [[fasting|fast]] while [[lactation|lactating]]. This combination of fasting with lactation requires the mother to provide large amounts of energy to her pup at a time when she is not eating (and often, not drinking). Mothers must supply their own metabolic needs while nursing. This is a miniature version of the [[humpback whale]]s' strategy, which involves fasting during their months-long migration from arctic feeding areas to tropical breeding/nursing areas and back.{{citation needed|date=April 2025}}
Because a phocid mother's feeding grounds are often hundreds of kilometers from the breeding site, she must [[fasting|fast]] while [[lactation|lactating]]. This combination of fasting with lactation requires the mother to provide large amounts of energy to her pup at a time when she is not eating (and often, not drinking). Mothers must supply their own metabolic needs while nursing. This is a miniature version of the [[humpback whale]]s' strategy, which involves fasting during their months-long migration from arctic feeding areas to tropical breeding/nursing areas and back.{{citation needed|date=April 2025}}


Phocids produce thick, fat-rich milk that allows them to provide their pups with large amounts of energy in a short period. This allows the mother to return to the sea in time to replenish her reserves. Lactation ranges from five to seven weeks in the [[monk seal]] to just three to five days in the [[hooded seal]]. The mother ends nursing by leaving her pup at the breeding site to search for food (pups continue to nurse if given the opportunity). "Milk stealers" that suckle from unrelated, sleeping females are not uncommon; this often results in the death of the mother's pup, since a female can only feed one pup.{{citation needed|date=April 2025}}
Phocids produce thick, fat-rich milk that allows them to provide their pups with large amounts of energy in a short period. This allows the mother to return to the sea in time to replenish her reserves. Lactation ranges from five to seven weeks in the [[monk seal]] to just three to five days in the [[hooded seal]]. The mother ends nursing by leaving her pup at the breeding site to search for food (pups continue to nurse if given the opportunity).  Phocids are known to deliberately nurse young that are not their own, this is particularly seen in individuals that have lost their own pup<ref>{{Cite journal |last1=Arso Civil |first1=Mònica |last2=Hague |first2=Emily |last3=Langley |first3=Izzy |last4=Scott-Hayward |first4=Lindesay |date=2021-08-17 |title=Allo-suckling occurrence and its effect on lactation and nursing duration in harbour seals (Phoca vitulina) in Orkney, Scotland |journal=Behavioral Ecology and Sociobiology |language=en |volume=75 |issue=8 |page=121 |doi=10.1007/s00265-021-03051-y |bibcode=2021BEcoS..75..121A |issn=1432-0762|hdl=10023/23793 |hdl-access=free }}</ref>."Milk stealers" that suckle from unrelated, sleeping females are not uncommon; this often results in the death of the mother's own pup through starvation<ref>{{Cite journal |last1=Baker |first1=J. R. |last2=Jepson |first2=P. D. |last3=Simpson |first3=V. R. |last4=Kuiken |first4=T. |date=1998-05-30 |title=Causes of mortality and non-fatal conditions among grey seals (Halichoerus grypus) found dead on the coasts of England, Wales and the Isle of Man |journal=The Veterinary Record |volume=142 |issue=22 |pages=595–601 |doi=10.1136/vr.142.22.595 |issn=0042-4900 |pmid=9682418}}</ref><ref>{{Cite journal |last1=Steiger |first1=G. H. |last2=Calambokidis |first2=J. |last3=Cubbage |first3=J. C. |last4=Skilling |first4=D. E. |last5=Smith |first5=A. W. |last6=Gribble |first6=D. H. |date=July 1989 |title=Mortality of harbor seal pups at different sites in the inland waters of Washington |journal=Journal of Wildlife Diseases |volume=25 |issue=3 |pages=319–328 |doi=10.7589/0090-3558-25.3.319 |issn=0090-3558 |pmid=2761005 |bibcode=1989JWDis..25..319S }}</ref>; another side-effect of milk stealing in some species of phocid is the formation of [[Super weaner|"super weaners"]]<ref>{{Cite web |date=2015-01-12 |title=Science Word of the Day: Super-weaner |url=https://www.nationalgeographic.com/science/article/science-word-of-the-day-super-weaner |access-date=2026-04-24 |website=Science |language=en}}</ref>.


===Growth and maturation===
===Growth and maturation===


The pup's diet is so high in [[calorie]]s that it builds up a fat store. Before the pup is ready to forage, the mother abandons it, and the pup consumes its own fat for weeks or even months while it matures. Seals, like all marine mammals, need time to develop the oxygen stores, swimming muscles, and neural pathways necessary for effective diving and foraging. Seal pups typically eat no food and drink no water during the period, although some polar species eat snow. The postweaning fast ranges from two weeks in the hooded seal to 9–12 weeks in the northern elephant seal.<ref>{{Cite journal|title = The energetics of lactation in the Northern elephant seal, ''Mirounga angustirostris''|journal = Journal of Zoology|date = 1986|pages = 21–33|volume = 209|issue = 1|doi = 10.1111/j.1469-7998.1986.tb03563.x|first1 = D. P.|last1 = Costa|first2 = B. J. Le|last2 = Boeuf|first3 = A. C.|last3 = Huntley|first4 = C. L.|last4 = Ortiz}}</ref> The physiological and behavioral adaptations that allow phocid pups to endure these remarkable fasts, which are among the longest for any mammal, remain an area of active study and research.
The pup's diet is so high in [[food energy]] that it builds up a fat store. Before the pup is ready to forage, the mother abandons it, and the pup consumes its own fat for weeks or even months while it matures. Seals, like all marine mammals, need time to develop the oxygen stores, swimming muscles, and neural pathways necessary for effective diving and foraging. Seal pups typically eat no food and drink no water during the period, although some polar species eat snow. The postweaning fast ranges from two weeks in the hooded seal to 9–12 weeks in the northern elephant seal.<ref>{{Cite journal|title = The energetics of lactation in the Northern elephant seal, ''Mirounga angustirostris''|journal = Journal of Zoology|date = 1986|pages = 21–33|volume = 209|issue = 1|doi = 10.1111/j.1469-7998.1986.tb03563.x|first1 = D. P.|last1 = Costa|first2 = B. J. Le|last2 = Boeuf|first3 = A. C.|last3 = Huntley|first4 = C. L.|last4 = Ortiz}}</ref> The physiological and behavioral adaptations that allow phocid pups to endure these remarkable fasts, which are among the longest for any mammal, remain an area of active study and research.


=== Feeding strategy ===
=== Feeding strategy ===


Phocids make use of at least four different feeding strategies: suction feeding, grip and tear feeding, filter feeding, and pierce feeding. Each of these feeding strategies is aided by a specialized skull, mandible, and tooth morphology. However, despite morphological specialization, most phocids are opportunistic and employ multiple strategies to capture and eat prey. For example, the leopard seal, ''Hydrurga leptonyx'', uses grip and tear feeding to prey on penguins, suction feeding to consume small fish, and filter feeding to catch krill.<ref>{{Cite journal|last1=Kienle|first1=Sarah S.|last2=Berta|first2=Annalisa|date=2016|title=The better to eat you with: the comparative feeding morphology of phocid seals (Pinnipedia, Phocidae)|journal=Journal of Anatomy|volume=228|issue=3|pages=396–413|doi=10.1111/joa.12410|pmc=5341551|pmid=26646351}}</ref>
Phocids make use of at least four different feeding strategies: suction feeding, grip-and-tear feeding, filter feeding, and pierce feeding. Each of these feeding strategies is aided by a specialized skull, mandible, and tooth morphology. However, despite morphological specialization, most phocids are opportunistic and employ multiple strategies to capture and eat prey. For example, the leopard seal, ''Hydrurga leptonyx'', uses grip-and-tear feeding to prey on penguins, suction feeding to consume small fish, and filter feeding to catch krill.<ref>{{Cite journal|last1=Kienle|first1=Sarah S.|last2=Berta|first2=Annalisa|date=2016|title=The better to eat you with: the comparative feeding morphology of phocid seals (Pinnipedia, Phocidae)|journal=Journal of Anatomy|volume=228|issue=3|pages=396–413|doi=10.1111/joa.12410|pmc=5341551|pmid=26646351}}</ref>


==See also==
==See also==
{{Portal|Mammals|Animals|Marine life}}
* [[Marine mammals as food]]
* [[Marine mammals as food]]


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[[Category:Earless seals| ]]

Latest revision as of 19:48, 21 May 2026

Not to be confused with Phocides, a genus of butterflies, Pholcidae, a family of spiders, or Phocoenidae, a family of delphinodea.

Earless seals[2]
Temporal range: Aquitanian–present Early Miocene – Holocene, possible late Oligocene record[1]
File:Seehund.jpg
Harbor seal, Phoca vitulina
Scientific classification e
Missing taxonomy template (fix): Phocidae
Type genus
Phoca
Linnaeus, 1758
Subfamilies
File:Phocidae distribution.png
Phocidae distribution

Template:Taxonbar/candidate

The earless seals, also known as phocids or true seals, are one of the three main groups of mammals within the seal lineage, Pinnipedia. All true seals are members of the family Phocidae (/ˈfoʊsɪdiː/). They are sometimes called crawling seals to distinguish them from the fur seals and sea lions of the family Otariidae. Seals live in the oceans of both hemispheres and, with the exception of the more tropical monk seals, are mostly confined to polar, subpolar, and temperate climates. The Baikal seal is the only species of exclusively freshwater seal.

Taxonomy and evolution

Evolution

File:Cranio Pliophoca etrusca, Orciano.JPG
Fossil Pliophoca skull

The earliest known fossil earless seal is Noriphoca gaudini from the late Oligocene or earliest Miocene (Aquitanian) of Italy.[1] Other early fossil phocids date from the mid-Miocene, 15 million years ago in the north Atlantic.[1][3] Until recently, many researchers believed that phocids evolved separately from otariids and odobenids; and that they evolved from otter-like animals, such as Potamotherium, which inhabited European freshwater lakes. Recent evidence strongly suggests a monophyletic origin for all pinnipeds from a single ancestor, possibly Enaliarctos, most closely related to the mustelids and bears.[4]

Monk seals and elephant seals were previously believed to have first entered the Pacific through the open straits between North and South America,[5] with the Antarctic true seals either using the same route or travelled down the west coast of Africa.[6] It is now thought that the monk seals, elephant seals, and Antarctic seals all evolved in the southern hemisphere, and likely dispersed to their current distributions from more southern latitudes.[7]

Taxonomy

Template:Cladogram

In the 1980s and 1990s, morphological phylogenetic analysis of the phocids led to new conclusions about the interrelatedness of the various genera. More recent molecular phylogenetic analyses have confirmed the monophyly of the two phocid subfamilies (Phocinae and Monachinae).[8][9][10][5] The Monachinae (known as the "southern" seals), is composed of three tribes; the Lobodontini, Miroungini, and Monachini. The four Antarctic genera Hydrurga, Leptonychotes, Lobodon, and Ommatophoca are part of the tribe Lobodontini. Tribe Miroungini is composed of the elephant seals. The Monk seals (Monachus and Neomonachus) are all part of the tribe Monachini.[11] Likewise, subfamily Phocinae (the "northern" seals) also includes three tribes; Erignathini (Erignathus), Cystophorini (Cystophora), and Phocini (all other phocines). More recently, five species have been split off from Phoca, forming three additional genera.[12]

Alternatively the three monachine tribes have been evaluated to familiar status, which elephant seals and the Antarctic seals are more closely related to the phocines.[13]

Extant genera

Subfamily Tribe Image Genus species
Subfamily Monachinae Tribe Monachini File:Monachus monachus.jpg Monachus Fleming, 1822
File:Monachus schauinslandi.jpg Neomonachus Slater & Helgen, 2014
Tribe Miroungini File:Mirounga angustirostris, Point Reyes (cropped).jpg Mirounga Gray, 1827
Tribe Lobodontini File:Ross-seal.jpg Ommatophoca Gray, 1844
File:Antarctica 2013 Journey to the Crystal Desert (8369556693).jpg Lobodon Gray, 1844
File:Leopard seal basking on Iceberg.jpg Hydrurga Gistel, 1848
File:Weddell Seal in Antarctica (8381225741).jpg Leptonychotes Gill, 1872
Subfamily Phocinae Tribe Cystophorini File:2016-klappmützemuseumkoenig.jpg Cystophora Nilsson, 1820
Tribe Erignathini File:Bearded Seal at Svalbard (cropped).jpg Erignathus Gill, 1866
Tribe Phocini File:Seehund2cele4.jpg Phoca Linnaeus, 1758
File:Pusa hispida hispida NOAA 1.jpg Pusa Scopoli, 1771
File:Harp seal at False Cape (cut).jpg Pagophilus Gray, 1844
  • Harp seal, Pagophilus groenlandicus (formerly Phoca groenlandica)
File:Ribbon-seal-male Josh London NOAAedit (16086029928) (cropped).jpg Histriophoca Gill, 1873
  • Ribbon seal, Histriophoca fasciata (formerly Phoca fasciata)
File:Halichoerus grypus He3.jpg Halichoerus Nilsson, 1820

Biology

External anatomy

File:Harbor seal with skeleton GS.jpg
Skeletal anatomy of a harbor seal. 1. Skull. 2. Spine. 3. Tail. 4. Hindlimb. 5. Forelimb. 6. Shoulder. 7. Pelvis. 8. Rib cage.
File:Phoca vitulina 02 MWNH 1464.JPG
Harbor seal skull (Phoca vitulina)

Adult phocids vary from 1.17 m (3.8 ft) in length and 45 kg (99 lb) in weight in the ringed seal to 5.8 m (19 ft) and 4,000 kg (8,800 lb) in the southern elephant seal, the largest member of the order Carnivora. Phocids have fewer teeth than land-based members of the Carnivora, although they retain powerful canines. Some species lack molars altogether. The dental formula is: Template:DentalFormula

While otariids are known for speed and maneuverability, phocids are known for efficient, economical movement. This allows most phocids to forage far from land to exploit prey resources, while otariids are tied to rich upwelling zones close to breeding sites. Phocids swim in a sideways motion with their bodies;[14] their fore flippers are primarily used for steering, whereas their hind flippers are used for underwater propulsion.[15] While phocids' streamlined bodies make them better long-distance swimmers than otariids, unlike fur seals, their hind flippers are bound to the pelvis and unable to be rotated forward for walking. As a result, they are clumsy on land, having to wriggle with their front flippers and abdominal muscles.

File:Seal kidney-- FMVZ USP-08.jpg
Seal kidney

Phocid respiratory and circulatory systems are adapted to facilitate diving into considerable depths, allowing them to spend long periods of time underwater. When a seal dives, air is forced from the lungs and into the upper respiratory passages, where gases cannot easily be absorbed into the bloodstream, protecting it from the bends. The middle ear is also lined with blood sinuses that inflate during diving, helping to maintain a constant pressure.[14]

Phocid bodies are more specialized for aquatic life than otariids, as supported by the presence of ear holes (as opposed to external ears in fur seals), retractable nipples, internal testicles,[16] and an internal penile sheath. Phocids are able to divert blood flow to a smooth layer of blubber underneath their skin to help regulate body temperature.[17]

Communication

Unlike otariids, phocine seals do not communicate by "barking". Instead, they communicate by slapping the water and grunting, with a few species having been documented to clap at each other underwater.[18] One study published in Animal Behaviour found that seals use rhythmic percussive signalling (clapping) in both "agonistic interactions" and display behavior.[19]

Conversely, monachine seals are well known to vocalize: Elephant seals often vocalize on land,[clarification needed] with the bulls being well known for roaring to establish dominance and identify themselves.[20] The Weddell and leopard seals are well known for their underwater singing.[21][22][23][24]

Movements

With short front flippers and because their rear flipper is unable to rotate, true seals cannot walk when out of the water like sea lions. As a result, they bounce themselves forward in a motion called galumphing;[25][26] the polar explorer Edward Wilson referred to the motion as lolloping.[27] It is also referred to as "worm-style" locomotion.[28]

Reproduction

Photo of seven adult and juvenile southern elephant seals packed closely on beach
Southern elephant seals in Argentina
File:Antarctica 2013 Journey to the Crystal Desert (8369569335).jpg
Weddell Seal in Antarctica
File:Pusa hispida saimensis ca 1956.jpg
Living only in Lake Saimaa, Finland, Saimaa ringed seals, a subspecies of ringed seal, are among the most endangered seals in the world, having a total population of only about 400 individuals.[29]

Phocids spend most of their time at sea, although they return to land or pack ice to breed and give birth. Pregnant females spend long periods foraging at sea, building up fat reserves, and then return to the breeding site to use their stored energy to nurse pups[30][31]. However, the common seal displays a reproductive strategy similar to that used by otariids, in which the mother makes short foraging trips between nursing bouts.[citation needed]

Because a phocid mother's feeding grounds are often hundreds of kilometers from the breeding site, she must fast while lactating. This combination of fasting with lactation requires the mother to provide large amounts of energy to her pup at a time when she is not eating (and often, not drinking). Mothers must supply their own metabolic needs while nursing. This is a miniature version of the humpback whales' strategy, which involves fasting during their months-long migration from arctic feeding areas to tropical breeding/nursing areas and back.[citation needed]

Phocids produce thick, fat-rich milk that allows them to provide their pups with large amounts of energy in a short period. This allows the mother to return to the sea in time to replenish her reserves. Lactation ranges from five to seven weeks in the monk seal to just three to five days in the hooded seal. The mother ends nursing by leaving her pup at the breeding site to search for food (pups continue to nurse if given the opportunity). Phocids are known to deliberately nurse young that are not their own, this is particularly seen in individuals that have lost their own pup[32]."Milk stealers" that suckle from unrelated, sleeping females are not uncommon; this often results in the death of the mother's own pup through starvation[33][34]; another side-effect of milk stealing in some species of phocid is the formation of "super weaners"[35].

Growth and maturation

The pup's diet is so high in food energy that it builds up a fat store. Before the pup is ready to forage, the mother abandons it, and the pup consumes its own fat for weeks or even months while it matures. Seals, like all marine mammals, need time to develop the oxygen stores, swimming muscles, and neural pathways necessary for effective diving and foraging. Seal pups typically eat no food and drink no water during the period, although some polar species eat snow. The postweaning fast ranges from two weeks in the hooded seal to 9–12 weeks in the northern elephant seal.[36] The physiological and behavioral adaptations that allow phocid pups to endure these remarkable fasts, which are among the longest for any mammal, remain an area of active study and research.

Feeding strategy

Phocids make use of at least four different feeding strategies: suction feeding, grip-and-tear feeding, filter feeding, and pierce feeding. Each of these feeding strategies is aided by a specialized skull, mandible, and tooth morphology. However, despite morphological specialization, most phocids are opportunistic and employ multiple strategies to capture and eat prey. For example, the leopard seal, Hydrurga leptonyx, uses grip-and-tear feeding to prey on penguins, suction feeding to consume small fish, and filter feeding to catch krill.[37]

See also

References

  1. ↑ 1.0 1.1 1.2 Lua error in package.lua at line 80: module 'Module:Citation/CS1/Suggestions' not found.
  2. ↑ Template:MSW3 Wozencraft
  3. ↑ Lua error in package.lua at line 80: module 'Module:Citation/CS1/Suggestions' not found.
  4. ↑ Lua error in package.lua at line 80: module 'Module:Citation/CS1/Suggestions' not found.
  5. ↑ 5.0 5.1 Fulton, Tara L.; Strobeck, Curtis (2010). "Multiple fossil calibrations, nuclear loci and mitochondrial genomes provide new insight into biogeography and divergence timing for true seals (Phocidae, Pinnipedia)". Journal of Biogeography. 37 (5): 814–829. Bibcode:2010JBiog..37..814F. doi:10.1111/j.1365-2699.2010.02271.x. S2CID 59436229.
  6. ↑ Savage, RJG & Long, MR (1986). Mammal Evolution: an illustrated guide. New York: Facts on File. pp. 94–95. ISBN 978-0-8160-1194-0.
  7. ↑ Lua error in package.lua at line 80: module 'Module:Citation/CS1/Suggestions' not found.
  8. ↑ Árnason, Úlfur; Bodin, Kristina; Gullberg, Anette; Ledje, Christina; Suzette, Mouchaty (1995). "A molecular view of pinniped relationships with particular emphasis on the true seals". Journal of Molecular Evolution. 40 (1): 78–85. Bibcode:1995JMolE..40...78A. doi:10.1007/BF00166598. PMID 7714914. S2CID 7537924.
  9. ↑ Arnason, Ulfur; Gullberg, Anette; Janke, Axel; Kullberg, Morgan; Lehman, Niles; Petrov, Evgeny A.; Väinölä, Risto (2006-11-01). "Pinniped phylogeny and a new hypothesis for their origin and dispersal". Molecular Phylogenetics and Evolution. 41 (2): 345–354. Bibcode:2006MolPE..41..345A. doi:10.1016/j.ympev.2006.05.022. PMID 16815048.
  10. ↑ Fulton, Tara Lynn; Strobeck, Curtis (2010). "Multiple markers and multiple individuals refine true seal phylogeny and bring molecules and morphology back in line". Proceedings of the Royal Society B: Biological Sciences. 277 (1684): 1065–1070. Bibcode:2010PBioS.277.1065F. doi:10.1098/rspb.2009.1783. PMC 2842760. PMID 19939841.
  11. ↑ Scheel, Dirk-Martin; Slater, Graham J.; Kolokotronis, Sergios-Orestis; Potter, Charles W.; Rotstein, David S.; Tsangaras, Kyriakos; Greenwood, Alex D.; Helgen, Kristofer M. (2014). "Biogeography and taxonomy of extinct and endangered monk seals illuminated by ancient DNA and skull morphology". ZooKeys (409): 1–33. Bibcode:2014ZooK..409....1S. doi:10.3897/zookeys.409.6244. PMC 4042687. PMID 24899841.
  12. ↑ Berta, Annalisa; Churchill, Morgan (2012). "Pinniped taxonomy: review of currently recognized species and subspecies, and evidence used for their description". Mammal Review. 42 (3): 207–234. Bibcode:2012MamRv..42..207B. doi:10.1111/j.1365-2907.2011.00193.x.
  13. ↑ Bonner, N. (1994). Seals and Sea Lions of the World. United Kingdom: Blandford. pp. 1–224. ISBN 978-0-8160-5717-7.
  14. ↑ 14.0 14.1 McLaren, Ian (1984). Macdonald, D. (ed.). The Encyclopedia of Mammals. New York: Facts on File. pp. 270–275. ISBN 978-0-87196-871-5.
  15. ↑ "Harbor Seal (Phoca vitulina)". www.adfg.alaska.gov. Retrieved 2026-02-06.
  16. ↑ Perrin, William F.; Würsig, Bernd; Thewissen, J.G.M. (2009). Encyclopedia of Marine Mammals. Academic Press. ISBN 978-0-08-091993-5.
  17. ↑ Lua error in package.lua at line 80: module 'Module:Citation/CS1/Suggestions' not found.
  18. ↑ Hocking, David; Burnville, Ben; Marx, Felix Georg (February 3, 2020). "Comment: Grey seals discovered clapping underwater to communicate". The Conversation. Retrieved April 15, 2025 – via Newcastle University.
  19. ↑ Kocsis, Kinga; Duengen, Diandra; Jadoul, Yannick; Ravignani, Andrea (January 2024). "Harbour seals use rhythmic percussive signalling in interaction and display". Animal Behaviour. 207: 223–234. Bibcode:2024AnBeh.207..223K. doi:10.1016/j.anbehav.2023.09.014.
  20. ↑ McCann, T. S. (1981). "Aggression and sexual activity of male Southern elephant seals, Mirounga leonina". Journal of Zoology. 195 (3): 295–310. doi:10.1111/j.1469-7998.1981.tb03467.x.
  21. ↑ Terhune, John M. (2017-04-13). "Through-ice communication by Weddell seals (Leptonychotes weddellii) is possible". Polar Biology. 40 (10): 2133–2136. Bibcode:2017PoBio..40.2133T. doi:10.1007/s00300-017-2124-1. ISSN 0722-4060. S2CID 23069267.
  22. ↑ Green, K.; Burton, H. R. (January 1988). "Do Weddell seals sing?". Polar Biology. 8 (3): 165–166. Bibcode:1988PoBio...8..165G. doi:10.1007/bf00443448. ISSN 0722-4060. S2CID 46256980.
  23. ↑ Rogers TL (2014). "Source levels of the underwater calls of a male leopard seal". The Journal of the Acoustical Society of America. 136 (4): 1495–1498. Bibcode:2014ASAJ..136.1495R. doi:10.1121/1.4895685. PMID 25324053.
  24. ↑ Rogers, Tracey L.; Cato, Douglas H. (2002). "Individual Variation in the Acoustic Behaviour of the Adult Male Leopard Seal, Hydrurga leptonyx". Behaviour. 139 (10): 1267–1286. Bibcode:2002Behav.139.1267R. doi:10.1163/156853902321104154. JSTOR 4535987.
  25. ↑ Dipper, Frances (2021). RSPB Spotlight: Seals. London: Bloomsbury Wildlife. p. 20. ISBN 978-1-4214-0305-2.
  26. ↑ Derocher, Andrew E. (2012). Polar Bears: A Complete Guide to Their Biology and Behavior. Baltimore: Johns Hopkins University Press. p. 73. ISBN 978-1-4214-0305-2.
  27. ↑ Schmidt, Jeremy (2023). Weddell Seals: Science, Life History, and Population Dynamics. Weddell Seal Science. p. 59. ISBN 978-1-881480-19-8.
  28. ↑ Esteban, Juan Miguel; Martín-Serra, Alberto; Pérez-Ramos, Alejandro; Rybczynski, Natalia; Pastor, Francisco J.; Figueirido, Borja (2023). "Investigating the land-to-sea transition in carnivorans from the evolution of sacrum morphology in pinnipeds". Journal of Mammalian Evolution. 30 (2): 341–362. doi:10.1007/s10914-023-09650-y. hdl:10630/26300. ISSN 1064-7554.
  29. ↑ "Saimaa Ringed Seal". Retrieved 22 December 2018.
  30. ↑ Lua error in package.lua at line 80: module 'Module:Citation/CS1/Suggestions' not found.
  31. ↑ "Grey seal pup season | Cumbria Wildlife Trust". www.cumbriawildlifetrust.org.uk. 2023-10-30. Retrieved 2026-04-24.
  32. ↑ Arso Civil, Mònica; Hague, Emily; Langley, Izzy; Scott-Hayward, Lindesay (2021-08-17). "Allo-suckling occurrence and its effect on lactation and nursing duration in harbour seals (Phoca vitulina) in Orkney, Scotland". Behavioral Ecology and Sociobiology. 75 (8): 121. Bibcode:2021BEcoS..75..121A. doi:10.1007/s00265-021-03051-y. hdl:10023/23793. ISSN 1432-0762.
  33. ↑ Baker, J. R.; Jepson, P. D.; Simpson, V. R.; Kuiken, T. (1998-05-30). "Causes of mortality and non-fatal conditions among grey seals (Halichoerus grypus) found dead on the coasts of England, Wales and the Isle of Man". The Veterinary Record. 142 (22): 595–601. doi:10.1136/vr.142.22.595. ISSN 0042-4900. PMID 9682418.
  34. ↑ Steiger, G. H.; Calambokidis, J.; Cubbage, J. C.; Skilling, D. E.; Smith, A. W.; Gribble, D. H. (July 1989). "Mortality of harbor seal pups at different sites in the inland waters of Washington". Journal of Wildlife Diseases. 25 (3): 319–328. Bibcode:1989JWDis..25..319S. doi:10.7589/0090-3558-25.3.319. ISSN 0090-3558. PMID 2761005.
  35. ↑ "Science Word of the Day: Super-weaner". Science. 2015-01-12. Retrieved 2026-04-24.
  36. ↑ Costa, D. P.; Boeuf, B. J. Le; Huntley, A. C.; Ortiz, C. L. (1986). "The energetics of lactation in the Northern elephant seal, Mirounga angustirostris". Journal of Zoology. 209 (1): 21–33. doi:10.1111/j.1469-7998.1986.tb03563.x.
  37. ↑ Kienle, Sarah S.; Berta, Annalisa (2016). "The better to eat you with: the comparative feeding morphology of phocid seals (Pinnipedia, Phocidae)". Journal of Anatomy. 228 (3): 396–413. doi:10.1111/joa.12410. PMC 5341551. PMID 26646351.

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