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

Why Is The Asian Small Clawed Otter Considered To Be An Indicator Species?

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 too.

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.