California sea lions swim with their front flippers and bend backwards
In 2004 a perfectly healthy California sea lion turned up sitting on a road in Merced County, far from the sea. The species is curious, clever and unafraid of people once used to them, which is why the US Navy trains it and aquariums love it.
Ranging along the Pacific coast between southeast Alaska and central Mexico, this eared seal usually hauls out on sandy or rocky beaches but happily occupies marinas, wharves and even navigation buoys. It can survive in fresh water for a while too, and has been seen near Bonneville Dam, about 150 miles up the Columbia River. French naturalist René Primevère Lesson described it in 1828. Its genus name, Zalophus, roughly means intense crest, a nod to the bony ridge that gives adult males a high, domed forehead tufted with white hair.
The sexes look very different. Males reach 2.5 to 2.7 metres and around 350 kilograms, with the heaviest on record at 660; females are about 2.1 metres and 100 kilograms. Females and young are tawny brown, while grown males are usually dark brown. A 2007 genetic study showed that the Galapagos and Japanese sea lions, once treated as subspecies, are separate species, the California and Japanese lines having split about 2.2 million years ago.
Unlike true seals, which kick with their hind limbs, otariids drive themselves with their large foreflippers, gliding between strokes. A flexible spine lets a sea lion arch its neck back far enough to touch its hindflippers, making tight turns possible. Its colour vision is limited to blues and greens, it hears underwater across 0.4 to 32 kilohertz, and its whiskers sense vibrations, though less precisely than a harbour seal's.
Diet centres on squid, octopus and fish such as anchovy, herring, hake and salmon, sometimes hunted cooperatively with dolphins. Orcas and great white sharks take sea lions in return, and survivors carry the scars. Males hold territories from May to August, but females move freely between them. The species is rated Least Concern, abundant enough that Oregon and Washington set annual culling quotas to protect fish.
Source: California sea lion
