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| Acrochordus granulatus is
a common estuary dweller. However, it seems we know much less
about the species than we know about some extinct creatures. |
Story by PONGPET MEKLOY Pictures
by SANSAREEYA WANGKULANGKUL
Never rush to judge someone
by his appearance, even if it's a snake. The Ngu pha khirew
(translated as rag snake), for example, may not look gorgeous; but
if you get to know it, you might get hooked. Well, that's what
happened to one woman anyway.
The species' Thai name comes from the fact that when coiled, the
snake's baggy skin makes it look like a crumpled rag. These living
rags are non-venomous and feed on fish.
Scientifically named Acrochordus granulatus, the species belongs
to a small family of aquatic snakes called Acrochordidae. Of the
world's three known members of this family, two species occur in
Thailand _ the other one is the better known elephant-trunk snake
(A. javanicus).
But while the much larger elephant-trunk snake lives in fresh
water, ngu pha khirew is found in estuaries and the sea.
Not much is known about this unglamorous reptile. Sansareeya
Wangkulangkul, who is working on her PhD at Chulalongkorn
University's Faculty of Science, is one of the very few who is
attracted to the species. Her study on A. granulatus in Phang-nga
Bay is sponsored by the Thailand Research Fund.
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| The banded pattern of ngu
pha khirew resembles that of the venomous true sea snakes. But
those deadly serpents have flattened, paddle-shape tail while
ngu pha khirew, like the one shown here, sport a tapered tail
that is only slightly compressed. |
``A unique characteristic of this family is
the reduced scales,'' says Sansareeya, explaining that, like its
relatives, the skin of ngu pha khirew is covered with tiny rough
scales. ``When you feel it with your fingers, it's like you're
touching the surface of a file. That's why its English common name
is file snake.''
With such minute scales all over the body _ even on the underside
which in most snakes is fitted with large ventral scales _ the
species cannot move efficiently on land. Climbing trees, of
course, is out of the question.
In the elephant-trunk snake, the rough surface that results from
such scale design helps ensure that prey in its constricting coil
won't slip away. However, similar use by ngu pha khirew is not
confirmed since the species' hunting behaviour has never been
observed.
``The snake has teeth that slant inwards. Once a fish is snapped
between the jaws of the snake, it's not easy for the fish to free
itself,'' she says. ``I tried with my finger.''
Sansareeya got her specimens from local fishermen in areas around
the Phang-nga Bay. They often find marine snakes in their fish
traps.
The researcher asked the men to keep the ngu pha khirew for her
study instead of just throwing them away. She keeps records of
environmental conditions of the sites where the snakes were
captured, then brings them to her lab in Phuket to examine them
and take measurements of both external and internal organs.
 |
| The mangroves are home to
ngu pha khirew. But it's not surprising to see the snake
venturing into open waters. |
``I also check out the content of their
stomachs _ to find out what they eat. And I found something
interesting,'' she reveals, smiling. ``Most of their prey are
gobies. Obviously, these snakes have a taste for expensive fish!
``Even more interesting is that I've never found a mudskipper in
the bellies of ngu pha khirew, despite the fact that mudskippers
are abundant in the mangrove and mudflats which are the snake's
habitats.''
According to Sansareeya, stomach content examination must be
conducted as soon as possible since the digestive system of ngu
pha khirew is highly efficient.
``It can finish off a whole fish overnight. So if you wait too
long, you might find nothing more than unidentifiable bits of
bones, or nothing at all,'' she says.
Other than fish, the researcher sometimes found parts of prawns in
the snakes' stomachs. ``But for now I can't say the species preys
on prawns, too. The crustaceans could have been eaten by the fish
which in turn was eaten by the snake.''
Sansareeya's engagement with ngu pha khirew has been going on for
over a year. However, even now the questions she has about the
species are still not answered _ except for one.
``Now I can distinguish males and females from their external
features,'' she says, adding that both sexes of the species look
very similar. In the past the surest way to identify the sex of
each snake was to check their reproductive organs which are hidden
inside the body.
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| The species' digestive
system is highly effective _ it can finish off an entire fish
overnight. The picture compares a just-swallowed fish with one
partially digested. The piece at the bottom is the head of the
second fish. |
The researcher points out that mature
females are usually larger than their male counterparts _ their
skulls are broader and their bodies thicker. ``Females tend to be
longer, too, reaching about 90 centimetres. Males are about 10
centimetres shorter.''
Asked about the importance of this finding, she explains: ``When
you're in the field and spot an animal, it helps if you can tell
the sex of that animal right away. Otherwise, you have to catch it
and bring it all the way to the lab to check.''
Male and female snakes, she continues, may have different
behavioural patterns and occupy different niches.
``For example, females _ since they are larger _ may prey on fish
bigger than the ones the males are after.''
Another thing Sansareeya is monitoring is the species'
reproductive cycle.
Females, she found, begin to produce eggs inside their bodies
around June and July. By November, the yolks become evident. ``I'm
not sure exactly when fertilisation happened. But snakes captured
in February were already carrying yolks with developing embryos,''
she says.
Female ngu pha khirew seem to be absent from bay waters in April
and May. Sansareeya thinks it's possible that during those months
the mother snakes might hang around in the mangroves _ the natural
nursery for many marine creatures _ to give birth to their
offspring. (The species bear live young.)
``The fishermen told me they saw several newborn ngu pha khirew in
the mangroves during that period,'' she says.
It's true Sansareeya's study still has a long way to go, yet the
determination of a woman who chose to devote the youthful part of
her life to an unglamorous species of snake is unlikely to
deteriorate with time.
All we have to do is wait and see the next secret of these living
rags that she'll unravel.
