Fur seals? There’s no such thing!

PIERRE CONSTANT gets bugged by people who persist in believing that fur seals are, in any sense, seals. Please let him set the record straight, with the help of his photographs

A long time ago, in the last century, I was a naturalist guide in the Galapagos Islands. Taking more than a month, a guide’s training in the Galapagos National Park, under the eyes of the Charles Darwin Research Station, was a serious affair. 

After the academic course, with classes led by the scientific authorities, and hours of self-study in the scientific library, a four-hour final examination was set to test our acquired knowledge.

Passing meant receiving the sought-after naturalist guide’s licence, enabling us to work officially on cruise and sailing boats in the park, which has been a World Heritage Site since 1978.

Depending on where you went in the archipelago, and which islands and sites you visited, it was always enchanting to see colonies of endemic Galapagos sea-lions (Zalophus wollebaeki) basking lazily in the sun on white, green, red or black sandy beaches. 

In some places, west of Santiago or Isabela Island and exposed to an upwelling of the cold Cromwell Current, you would also encounter a different species: the Galapagos fur sea-lion (Arctocephalus galapagoensis). Its ancestor Arctocephalus australis had migrated from Antarctica along the coast of Chile and Peru on the well-known Humboldt Current.

Every time I heard people refer to these mammals as ‘seals’ or even ‘fur seals’, I felt at best agitated and at worst irritated. I made it a point to explain systematically to visitors the differences between a seal and a sea-lion. 

Some hard-headed tourists, convinced that they knew better, refused to get it, or decided that the animals must be seals because “they had always been called that”.

The pinniped family

Seals and sea-lions are both pinnipeds, a diverse group of semi-aquatic marine mammals once  commonly known as earless (or true) seals and fur seals.

The true seals belong to the Phocidae family, whereas sea-lions belong to the Otariidae family, which has two distinct subfamilies: Arctocephalinae, with its two genera and Otarinae, which has five. The walruses of the Arctic belong to another family still, the Odobenidae.

Sea-lions come mostly from the Southern Hemisphere – except for the California sea-lion (Zalophus californianus), ancestor of the Galapagos sea-lion, and the Steller sea-lion (Eumetopias jubatus) of the Arctic. 

On the other hand, seals are mostly from the Northern Hemisphere – apart from the southern elephant seal (Mirounga leonina), crabeater seal (Lobodon carcinophaga), Weddell seal (Leptonychotes weddellii) and leopard seal (Hydrurga leptony), famous in Antarctica and a ferocious predator of penguins.

The main differences between seals and sea-lions? Seals have round eyes and a pointed nose, no visible ears and creep on their stomach for locomotion.

Sea-lions have almond-shaped eyes, a square muzzle, external (tube-like) ears and can move forward on their front flippers. These flippers also help them to stand erect from the belly up, as if using a pair of crutches. 

What people commonly call a fur seal is therefore erroneous, because these are in fact “fur sea-lions”. They have so-called thick double fur, but also all the characteristics of a sea-lion, though they are smaller and have a conspicuously more pointed nose.

Fur sea-lions

The Otariidae sea-lions’ Arctocephalinae subfamily comprises two genera: Arctocephalus, or the southern fur sea-lion (there are eight species) and Callorhinus, the northern fur sea-lion. The latter’s single species, Callorhinus ursinus, is found in the Arctic Ocean. 

All eight Arctocephalus species originated in the Antarctic, from when the living conditions were less extreme and polar than they are now. 

This has triggered speciation about when different groups of the original South American fur sea-lions (Arctocephalus australis) migrated north in search of a better environment.

They used north-flowing marine currents: the Humboldt for the Juan Fernandez (Arctocephalus philippi) and Galapagos fur sea-lions, or the Benguella for the Cape fur sea-lions (Arctocephalus pusillus).

The Australian (Arctocephalus pusillus doriferus) and New Zealand fur sea-lions (Arctocephalus forsteri) followed similar routes to reach the final destinations indicated by their names.

So next time you hear someone talking about fur seals, make sure to brief them on the correct denomination, because the old one is obsolete and misleading. You’ll make my day!

Also by Pierre Constant on Divernet: DIVING INTO CUBA’S FAR WEST, NORONHA: AN ATLANTIC DIVING HOTSPOT,  DIVING LIFOU, A FOSSIL ATOLL, FLORES, GATEWAY TO KOMODO, HELL’S BELLS AND OTHER YUCATAN CAVE SPECIALS, VANUATU BEYOND THE COOLIDGE and DIVE-TRIP: MUSANDAM TO MUSCAT