River Otter is a carnivorous marine animal distributed all over the world. Especially seen in the American continent more widely than in any other place, the river otter belongs to the Mustelidae family of weasels. In Kerala, River Otters are protected in some of the wildlife sanctuaries. It is familiar to the natives of Kerala by the informal term ‘neer nai’ which means ‘water dog’ in the Malayalam language.
Otters are of Carnivora order coming under the Mammalia class. All genuses belong to the subfamily of Lutrinae under the Mustelidae family. They are excellent swimmers. The soft underfur and long guard hair helps them from getting wet, while swimming. They have long slim bodies with short limbs. Many of the River Otters can swim at an average speed of seven miles per hour. They are three to four feet long and usually weigh 15 to 25 pounds at an average.
Being carnivorous, the diet of various species of otters includes fishes, crabs, frogs, crayfish and shellfishes. They choose frequently varying habitats like lakes and ponds, but usually live in marshes and along wooded rivers and streams.
In Kerala, though rare, three of the species of River Otters are found from the backwaters of Thalassery and Kozhikode. They are Eurasian Otter (Lutra Lutra), Smooth-coated Otter (Lutra Perspicillata) and Small-clawed Otter (Aonyx Cinerea). The Eurasian Otter is seen in Eravikulam and Parambikulam wildlife sanctuaries along the coast of Periyar river. The Eurasian Otter is known sometimes as European Otter or Common Otter.