Otters can be found on every continent except Antarctica and Australia. They are very social and playful mammals, most commonly found in river basins. Each species has distinctive behaviors, ranging from holding hands to kidnapping youngsters for ransom.
It belongs to the subfamily Lutrinae in the family Mustelidae.
They are related to skunks, wolverines, badgers, and weasels.
There are 13 species of otters.
Sea otter, found along the coast of the Pacific Ocean in North America and Asia;
Congo clawless otter, found in the lower Congo basin;
Asian small-clawed otter, found in Southeastern Asia, including Indonesia and the Philippines;
African clawless otter, found along the eastern coast of Africa (from South Africa to Kenya), southern coast of Africa (from Ethiopia to Cameroon), and central inland Africa;
Giant otter, found in La Plata River system;
Marine otter, found on the western coast of South America;
Neotropical river otter, found in South America, Central America, and the island of Trinidad;
Southern river otter, found in Argentina and Chile;
North American river otter, found throughout most of the continent (from the Rio Grande to Alaska);
Smooth-coated otter, found in southern and southeast Asia);
Spotted-necked otter, found in sub-Saharan Africa, in Lake Tanganyika and Lake Victoria;
Hairy-nosed otter, found in Southeast Asia;
Eurasian otter, found widespread in Europe, Asia, and Africa.
The largest of the species is the Giant otter.
It can measure up to two meters in length.
The Asian small-clawed otter is the smallest of the species.
It measures an average of 85 centimeters in length.
90% of sea otters live on the coast of Alaska.
Otters have webbed feet.
Along with muscular tails they use as rudders, they are agile swimmers, adapted to efficient hunting in the water.
Otters can close their nostrils and ears while diving, preventing water from getting in.
Males are called dogs or boars, and females are called bitches or sows.
The average lifespan of an otter is 16 years.
They primarily feed on fish, but also on crabs, crayfish, and frogs.
Depending on the species, they can also feed on small birds and mammals, shellfish, clams, and sea urchins.
They have a high metabolic rate, and thus, depending on species, have to consume from 15% to 25% of their body weight every day.
Their fur is waterproof, although not covered in a fatty layer.
Males reach sexual maturity at the age of three, and females at the age of two.
Depending on the species, otters can be both monogamous and polygynous.
Promiscuous behavior is, however, more common.
Females give birth to one pup after two to three months of gestation.
Pups become fully independent after a year, until which time they stay with their family.
Except for sea otters, which give birth in the water, other otter species give birth in dens located ashore.
Pups born in captivity and raised by humans may grow too attached to them to be safely released into the wild.
Instead of hand-rearing pups, it is better to present one to a female, who most likely will adopt it and care for the pup herself.
Most of the otter species sleep on land, except for the sea otters that sleep floating in groups called rafts.
While sleeping, they entangle themselves in kelp to avoid floating away.
Giant otters can swim at a top speed of 14 kph.
Otters have a loose patch of skin under their armpits that they use as storage for rocks and food.
Sea otters are known to use tools.
They float on their backs with a rock placed on their belly they use to crack open clams and mollusks.
Some otters keep the same rock their entire life.
Depending on the species, otters can hold their breath underwater for five to eight minutes.
Their lung capacity is approximately 2.5 times larger than other mammals of similar size.
Otters' excrements have its own name.
It is called spraint and emits a smell, described by some scientists as similar to jasmine tea or violets. Otters use spraint to communicate with each other.
Cat excrements pose threat to otters.
The rather common for cats parasite called Toxoplasma gondii can be deadly to otters.
Otters can smell their prey underwater.
They exhale air bubbles with captured smell and inhale them quickly again.
They are very sociable and playful.
Otters are known for rubbing against each other, which refreshes their coats. They also wrestle with one another, water slide, and juggle rocks. Scientists theorize that either they play with rocks like cats with balls of yarn, or they signalize hunger (since rocks help them open clams and mollusks).
They spend a lot of time on grooming.
Dirty fur disrupts the regulation of body heat and affects their floating ability.
In southern Bangladesh, otters help humans in fishing.
They chase fish into the fishing nests and get a few fish to eat as a reward. This practice was once more common and dates back to the 6th century. Marco Polo, a Venetian merchant and explorer, observed this unique practice called “otter fishing” in the Yangtze River in the 13th century.
Followers of Zoroastrianism believed otters to be sacred.
They considered otters sea dogs, helping with purifying water by eating dead animals before they started rotting. Killing otters was strictly forbidden, and if any dead otter was found, Zoroastrians would hold special ceremonies in their honor.
They suffer from habitat loss, water pollution, and excessive poaching.
Out of all 13 otter species, five are classified as near threatened, two as vulnerable, five as endangered, and only the North American river otter is classified as least concerned by the IUCN Red List.