Australian Sea Lion

Australian Sea Lion
Vocalizing on Beach
Conservation status
Endangered (IUCN 3.1)[1]
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Carnivora Suborder: Pinnipedia Family: Otariidae Subfamily: Otariinae Genus: Neophoca Gray, 1866 Species: N. cinerea
Binomial name
Neophoca cinerea (Péron, 1816)

The Australian Sea Lion (Neophoca cinerea) is a species of sea lion that breeds only on the south and west coasts of Australia. Today there are about 10,000 Australian Sea Lions following the introduction of the Australian National Parks and Wildlife Act of 1972 which prohibited a harvest that began in earnest as soon as Europeans colonised the continent.

The Australian Sea Lion inhabits the ocean around Australia, and nowhere else. They only eat at sea, where they hunt fish, squid, and other sea creatures. They have front-flippers that allow them to propel quickly through water and be more agile on land by being able to walk on all four flippers.

The breeding cycle of the Australian sea lion is unusual within the pinniped family. It is an 18 month cycle and is not synchronized between colonies. The duration of the breeding season can range from 5 to 7 months and has been recorded for up to 9 months at Seal Bay on Kangaroo Island.

Bulls do not have fixed territories during the breeding season. The males fight other males from a very young age to establish their individual positions in the male hierarchy and during the breeding season, dominant males will guard females for the right to breed with her when she comes into oestrus. A female comes into season for about 24 hours within 7 to 10 days after she has given birth to her new pup. She will only look after the new pup and generally fights off the previous season's pup if it attempts to continue to suckle from her.

Male Australian Sea Lions are also known to kill young, as an act of defence of territory.

Two females from the July 2001 breeding season were observed having their first pups where they were born. The females were part of a research project where 55 pups from that season were observed from the date of birth and their birth locations were also recorded. The females have proven a theory that the birth sites of the females are extremely important in their selection of future birth sites for their pups, which is another reason why the protection of existing colonies is so important to the species.

Sea lions on Kangaroo Island beach

Phylogeny

The Australian Sea Lion come under the order carnivora which includes animals such as dogs, cats, bears, otters, hyenas, walruses etc. Pinnipedia have then divergred from carnivora, where you can see their closer relatives such as true seals, earless seals and walruses. Australian sea lions closest relatives though, are sea lions, eared seals and fur seals who all come under the same family otariinae.

Analogous and Homologous structures

The Australian Sea Lion have many similar analogies with other species. For instance sea lions use their flippers in a wing like motion to propel themselves through the water. This is an analogous feature shared among many animals. For example penguins are from a complete different class of flightless bird species. Penguins also use a similar method whilst in the water; their wings serve little point on land whereas in the water their wing structure acts similar to flippers and allows them to dart around with quick movements. This rapid movement gives sea lions their speed whilst underwater and helps them to catch their prey.

Australian sea lions have very well-developed facial whiskers. Like all pinnipeds such as seals and walruses, this useful homologous structure helps the sea lion to feel their way under the water and sense their prey. This is an inherited feature shared amongst all of the sea lions close relatives.

References

Wikimedia Commons has media related to: Australian Sea Lion

• Shannon Leone Fowler (2005). Ontogeny of diving in the Australian sea lion. Ph.D. thesis. University of California, Santa Cruz.

• Randall R. Reeves, Brent S. Stewart, Phillip J. Clapham and James A. Powell (2002). National Audubon Society Guide to Marine Mammals of the World. Alfred A. Knopf, Inc. ISBN 0375411410.