Baby sea otter held at the Monterey Bay Aquarium
after being found orphaned on the beach.
And done.
Just kidding. As adorable and amazing as that was there is so much more to these furry balls of walking "awws". So here are some general facts about otters followed by one or two of my favorite species.
There are 13 extant species of otters found in various corners of the globe in a variety of habitats from the semi-aquatic to the fully marine. They range in size from the relatively tiny, Oriental small clawed otter (Amblonyx cinerea) to the absolutely massive, by otter standards, giant river otter (Pteronura brasiliensis).
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| Left: Oriental small clawed otter (Amblonyx cinerea). The smallest of the otter species it grows to between 70-100 cm of which approximately 1/3 is its tail. Right: Giant river otter (Pteronura brasiliensis). The largest of the otters, at least by length, they can grow up to 1.7 m long (over 5 1/2 feet). |
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| Various Mustelidae (Clockwise from left): American marten, ferret, wolverine, "Pepper" (otter), honey badger |
Sea otter using a rock to smash open clams.
Sea Otter, Enhydra lutris
Sea otters are the "odd man out" of the Lutrinae family. Not only are they the heaviest otter species, and in fact the heaviest of all the weasel family. They are also the only otter capable of living their entire lives without leaving the water. Found along the Pacific coasts of North America and Asia these otters are renowned for their pelts. They have the densest fur of any animal, with approximately 150,000/cm squared (~1,000,000 per square inch). In comparison chinchillas, with the densest fur of any terrestrial animal, have on average 24,000/cm squared (~155,000 per square inch). While their incredibly thick fur may help protect sea otters from the cold of the Pacific it also nearly led to their extinction with poachers drastically reducing their numbers during the 18 and 19th centuries. When the Treaty for the Preservation and Protection of Fur Seals (which included a moratorium on sea otter harvesting) was signed in 1911 by Russia, Japan, Great Britain on behalf of Canada, and the US population estimates ranged from only 1,000-2,000 individuals. Since then they have rebounded to ~125,000 individuals worldwide (as of 2012), but they are still listed as Endangered by the IUCN Red List.
Sea otters are a classic example of a keystone species. This means that their removal from an environment or ecosystem would have a much greater impact than their size and numbers would suggest. For example, kelp forests are prime marine real estate. They provide a 3-dimensional environment for organisms to live in, hide from predators, feed on, etc. These forests are anchored to the sea floor by the kelp's holdfast (like the roots of a tree), and these holdfasts are food for many benthic organisms such as sea urchins. While there are sea otters present they regulate the urchin population, however, if you remove the sea otters the urchin population explodes. This leads to the destruction of the kelp forest as the urchins destroy the holdfasts quicker than new kelp can settle and grow. Therefore without sea otters the entire ecosystem is destroyed as shown in this video from the PEW Charitable Trusts:
The importance of sea otters.
European Otter, Lutra lutra
The European otter, also known as the Eurasian otter or the Old World otter, has the widest range of all the otter species. They span three continents (Europe, Africa, Asia) from Ireland to China, and as far north as Scandinavia down to North Africa and South-East Asia. This species mainly lives in freshwater, but can be found along the coast although they require freshwater regularly to clean their coats. These otters are also highly territorial along sex lines, meaning that male-female territories may overlap, but never male-male or female-female.
Giant River Otter, Pteronura brasiliensis
As mentioned earlier giant river otters, as their name suggests, are the largest of the otters and in fact the largest of any Mustelidae (in terms of length, as mentioned sea otters are the heaviest). They are also strongly social species, with family groups ranging from 2-20 individuals held together by a main breeding pair. Their social ties allow them to work and hunt together successfully. They are known as ariranha in Brazil which translates to water jaguar, and in Spanish they are lobo del rio, or river wolves. The comparisons suggested by these names are well earned as this video shows:
Clip from BBC 2 documentary showing a family of giant
river otters attacking and dispatching a caiman.
These otters are apex predators, which is no easy task in the Amazon. Their diet consists mainly of fish including catfish and piranhas, but they have also been known to take down caimans and anacondas! When full grown these otters have no serious natural predators (although occasional predation by jaguars, and anacondas has been suggested, but never observed) and so their greatest threats come from humans (what a shock). They are poached for their fur, and are threatened by habitat destruction. The IUCN Red List classifies them as Endangered due to the threats facing them which are compounded by the difficulties to recover and re-colonization (they are a slow growing, late breeding species).
Well I think that's probably enough otter talk for one day. I will leave you with a couple cute videos of otters (the last one I took myself at an otter sanctuary near Plymouth in the UK).
Sources
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