Otters are members of Mustelidae, the
weasel family. They are highly inquisitive predators with
voracious appetites and rapid metabolisms. Like their cousins—such as weasels, ferrets—most otters have a pair of scent glands at the base of the
tail, which they use for scent marking their territories. However,
otters differ from their land-dwelling cousins in a very important
way: they are specially adapted for life in the water.
The bodies of otters are generally long
and slender, with flattened tails that they use like a rudder to
steer through the water. They all have webbed hind feet and most
have webbing on the front feet, making them very strong and agile
swimmers. For the most part, otters divide their time between the
land and the water. They are very opportunistic predators and they
will occasionally take prey such as insects and small mammals while
on land. However, otters do the bulk of their hunting underwater,
coming ashore only to rest, mark their territories, or care for
photo M Noonan
The water in which otters feed is often
very muddy or dark, making hunting by eyesight difficult at best.
To cope with these conditions otters have stiff whiskers, called vibrissae, around their faces and on
their elbows. The vibrissae help otters feel the vibrations caused
by swimming prey, allowing them to track fish, frogs or crustaceans
in water that is murky or deep.
These waters may also be fairly
cold, and (unlike marine mammals like seals and whales) otters do not have a layer of blubber to keep them warm. Instead, otters fluff their fur with their paws to trap air in their
thick coats. The trapped air acts as insulation from the cold.
The thirteen species of otter have a
nearly global distribution and can be found on every continent
except Antarctica and Australia. The populations of each species are
tracked by the World Conservation Monitoring Centre, and many
species are listed as vulnerable or endangered. The greatest threats
to otters come from humans, either through habitat loss or by
chemical pollution of the waterways in which the otters live