Questions and Answers: In-Depth Responses
I am doing a real big school report about asian small clawed otters and
I was wondering if I could get some information about these magnificent
animals from you. Any information can help.
Why is the asian small clawed otter considered to be an indicator species?
Who first descovered the species?
How many otters live in a group together?
How many asian small clawed otters are there still in the world?
Where do they usually hunt for food?
Why do they have the big hump on their back?
Why are they considered to be a threatened species?
Aimee Fairchild, 12 March 2009
Response from Lesley Wright
Why Is The Asian Small Clawed Otter Considered To Be An Indicator
Asian Small-Clawed Otters are top-of-the-chain predators i.e. they eat
a lot of things and nothing eats them (usually – occasionally a crocodile
might). They eat mainly crustaceans and molluscs, which feed on the
microorganisms that best absorb pollution. This means that any pollution
in the environment gets concentrated in the crabs, and then in the otters
that eat the crabs (biomagnification). If the otters are healthy,
it indicates that all of the animals under them in the food chain are healthy. Basically,
healthy otters mean a healthy environment.
Who First Descovered The Species?
Obviously local people have always known about them. The first formal
description was published in 1815, and was done by Johann Karl Wilhelm Illiger
in 1815 (it was published actually two years after his death). He
was a Professor of Zoology, and curator of the Natural History Museum in
Berlin, so I should think he was working from a stuffed otter in his collection. There
is no record of where it came from, so we don’t know which Westerner
was first to find them.
How Many Otters Live In A Group Together?
Asian Small-Claws live in family groups around the parents, who are the
only ones that breed. Litters of young do not leave the family group
but stay together and help raise the young, rather like wolves do. This
is called the Alpha system as the parents are the dominant members of the
group (the Alpha pair). When one of the original parents dies, the
otter family will split up and each otter go its way to find an unrelated
mate and start its own family.
Depending on how long the parents live, and how successful they are at
raising young, and how many they have in each litter (depending on the food
supply), a group of this species could potentially be very large. The
biggest group I know of is about 30, in Thailand. Most usual sizes
are around 8 to 12 otters. This is the only species that lives in
such big groups.
How Many Asian Small Clawed Otters Are There Still In The World?
We don’t know. They were considered very common till two years
ago when researchers started to look at their distribution and found they
had vanished from much of their range. I would estimate there are
probably around 5000 left in the wild, but there actually could be far fewer.
Where Do They Usually Hunt For Food?
These otters prefer shallow water and muddy areas, so they mainly hunt
in swamps, small creeks, estuaries, beaches, ditches and paddy fields. They
like places where there are a lot of insects, molluscs and crustaceans,
although they will also eat birds eggs and will catch and eat birds, rats
and mice. They are known to eat small snakes, worms and lizards
Why Do They Have The Big Hump On Their Back?
They don’t! They are shaped pretty much like a cat with shorter
legs. Their back legs are longer than their front legs though, so
when they are running along, they hump up their backs to bring their longer
back legs forward, like cats do when they are running fast. They do
have a lot of muscle in their hindquarters for swimming and jumping, but
they do not have a hump.
Look at the running otter animation at http://www.otterjoy.co.uk/otterinfo/lontra/longicaudis/longicaudis_locomotion.html
Why Are They Considered To Be A Threatened Species?
In the areas where they live, in south-east Asia, there is a high and growing
population, and a lot of industrial development. The swamps and marshes
where they live are being drained for agriculture, housing and industry,
and there is more and more pollution by industrial effluent such as heavy
metals (Mercury, Cadmium, Lead and so on) and PCBs. Agricultural use
produces a lot of pesticide spray and so on, Human housing results in sewage
being pumped into rivers and wetlands, and a lot of trash in the environment. All
this affects the otters because it accumulates in their food and eventually
kills them through liver or kidney failure.
In addition, the development of facilities farming prawns and shrimp leads
to them being killed as pests. They are also killed for going into
paddy fields hunting snails and so on, because in doing so, they accidentally
uproot the rice plants.
They are also killed by people’s pet dogs which are always a big
problem for all small wildlife. Dogs also carry a lot of diseases
which otters can catch such as rabies and canine distemper. They can also
catch jaundice and hepatitis from human sewage.
In much of the geographical area where they live, they are also hunted
for their skins, which are made in to boots and shoes.
Response provided 19 March 2009