Sea Otters
Kelp Management Specialists Hunted to the Edge of Extinction
Important for maintaining their own habitat and very well adapted for their life there.
The Sea Otter (Enhydra lutris) once lived all round the Pacific Rim, but hunting brought it close to extinction. Their adaptations to living in the sea are unique, and they are of vital importance for the survival of Kelp Forests.
Sea Otters – A Keystone Species
All species in a habitat have their part to play, but some are so important they are crucial to its very survival. The Sea Otter is just such a species; it is necessary for the survival of Kelp Forests. Sea Urchins are capable of rapidly destroying kelp by nibbling away at the holdfasts (which anchor the kelp to the sea-bed), and the urchins are only kept under control by Sea Otters who like to eat them. Remove the Otters and the urchins have a field-day, rapidly destroying the kelp. This is very important because the Kelp Forests are critical for the survival of many species, including the young of many that are fished commercially.
Sea Otters – Fur Hunting
When the Russians discovered Sea Otters in the seventeenth century their fur became a luxury item in the fur trade (along with sable). Moving east around the Pacific Rim the Russian hunters soon depleted the Sea Otter populations in Alaska (so much so that it became useless for hunting and they sold it to America in 1867). In the meantime Captain James Cook had discovered the Sea Otters in 1776, and once the value of the fur was recognised Europeans took over where the Russians left off, hunting the Sea Otter to the brink of extinction along the Pacific coast of America. Hunting was banned in 1911 and populations (especially in Alaska) have recovered to some extent.
Sea Otters – Marine Adaptations
True Marine Mammals are all adapted to life in the ocean in similar ways (see blog), with lots of fat under their skin to conserve heat for example. Sea Otters are a bit different, their adaptations to life in the sea suggest that they are only part-way to becoming fully ‘marine’. Sea Otters conserve heat by having incredibly dense fur (almost their downfall!), with a million hairs to the square inch – but this only works if you come to the surface regularly to dry out your hair. Similarly the Sea Otters have developed enormous lungs and ‘hold their breath’ when underwater, but this strategy only works if you restrict yourself to shallow dives (seals have much smaller lungs and whales empty their lungs before deep dives). Sea Otter eyes are equally good (very good) under water and in air. These adaptations all suggest that the Sea Otters are only part-way to becoming ‘Marine Mammals’ (but maybe this is purely semantic?).
Sea Otters – Current Research
Populations of Sea Otters are being monitored throughout their range to assess their recovery after the hunt ban, and also to see how badly they are affected by oil spills. Their relationship with Kelp Forests is also being closely studied.
Ref: Alaska Science Center - Sea Otter Projects
watch a video of two Sea Otters holding hands at Vancouver Aquarium and see Sea Otters and Pollution
Other articles by John Blatchford
