Enhydris chinensis - Chinese Water Snake

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Hans Breuer (twoton)
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Enhydris chinensis - Chinese Water Snake

Post by Hans Breuer (twoton) » June 18th, 2010, 10:42 pm

Not even a week ago, in another thread, I bemoaned the futility of searching for Enhyrdis water snakes, to wit:

"There's a large lily pond 20 minutes from my house where E. plumbea can be found.....if you're good. They love to burrow into the mud until only the eyes are sticking out and then stay there and wait for frogs. Since the dorsal region of these snakes is exactly the same color of the mud, searching for them is very frustrating. Oh, they're nocturnal, too. So far, I've never seen a live one. Plus, they're mildly venomous and supposed to be very pissy-tempered. I wonder if a search is worth it?"

Well, yesterday a friend who works at the Taipei Zoo called me and asked me if I and the boys would like to partake in a zoo-sponsered herp survey of the above-mentioned water lily ponds. That lily pond has come to prominence as it's one of the last places in Taipei County where the rare Taipei Grass Frog (Rana taipehensis) can be found. The lilies (Nympheae sp.) used to be farmed commercially by an old farmer, and when the Taipei Zoo found out about the Taipei Grass Frog, they offered him monetary compensation if he'd quit using pesticides in his ponds. That he did, and today the ponds are a superb example for localized biodiversity. Ten kinds of anurans, countless types of aquatic insects, and a dozen species of snakes make the ponds a great place for any naturalists - if they're patient and bring waders.

So last night we went there (without waders), did a few rounds around the ponds, enjoyed the frog chorus and the hunting dragonfly nymhps, almost stepped on a Many-banded krait (Bungarus multicinctus), and finally hit the jackpot - a juvenile Chinese Water Snake, aka Enhydris chinensis, a lifer for me.

This is what http://www.snakesoftaiwan.com has to say about this species:

Homalopsine snakes are usually considered a subfamily, the Homalopsinae, of the family Colubridae. All of them have valvular nostrils combined with a mechanism for complete mouth closure, and a trachea that can extend to the internal nostrils within the mouth, all of which facilitate their underwater lifestyle. Most also have small eyes located close to the top of the head, enlarged rear maxillary teeth that are grooved and other anatomical characteristics that suggest they all share a common ancestor.

Enhydris chinensis is a crepuscular or nocturnal snake found in fresh water, such as ponds, rice paddies, and ditches, but its habitat is not limited to those areas: E. chinensis is Taiwan's only colubrid that can also thrive in brackish water, e.g. some of the ponds in Taipei County's Guandu Nature Park (關渡自然公園). Although it spends almost all of its time in the water, it can be found on land after heavy rainfalls.

Fish and frogs are its staple foods. In August and September, females give birth to 3-21 young. When disturbed, this snake has a tendency to submerge into soft mud. Its defensive behavior consists mostly of feigned strikes, accompanied by lateral or vertical head jerks and quick vertical jumps. It may also launch a profuse flow of semi-fluid feces with a very distinctive and pungent odor.

This is Taiwan's rarest opistoglyphous (= rear-fanged, see footnote (1)) species, and is mildly venomous. While its venom is not fatal to humans, bites may lead to swelling, itching and/or allergic reactions.

In Chinese medicine, Enhydris chinensis is the species most commonly used for the production of snake oil.


So, here are some shots of this 5-inch juvenile. Of course, while we were shooting, some guy came up and showed us a few photos he had taken the day before of a 15-inch adult eating a large frog, thereby somewhat diluting our joy about the find. :-)

Some habitat shots first (many more here)

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The snake:

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When we were almost done, some guy came up with another juvie he'd caught, and we had a few group shots:

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wayne_fidler
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Re: Enhydris chinensis - Chinese Water Snake

Post by wayne_fidler » June 18th, 2010, 10:46 pm

do you have any pics of the belly?

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Hans Breuer (twoton)
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Re: Enhydris chinensis - Chinese Water Snake

Post by Hans Breuer (twoton) » June 18th, 2010, 11:13 pm

Unfortunately not. We tried, but it wouldn't stay put on its back, and due to its mild venom I didn't want to handle the animal too closely.

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moloch
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Re: Enhydris chinensis - Chinese Water Snake

Post by moloch » June 19th, 2010, 12:18 am

Interesting report, Hans. Glad you found it!

Regards,
David

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Warren
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Re: Enhydris chinensis - Chinese Water Snake

Post by Warren » June 19th, 2010, 3:59 am

Great post! I messed with Enhydris plumbea in Thailand. I had no idea about the venom, so I was careful not to tail the little buggers and there was a lot of splashing around with a mini-hook and a headlamp before I got ahold of one. It seems a shame to photo on wood with so many gorgeous flowers and plants around. Did you consider having someone hold the tail underwater? Then you could have amazing, natural-looking shots with the snake on the surface and a water lily in the same frame...and all you need is a work glove to protect you.

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Re: Enhydris chinensis - Chinese Water Snake

Post by Tim Borski » June 19th, 2010, 5:04 am

Hans, how "mildly venomous"? Gorgeous snakes. Congrats on a lifer!
Tim

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Viridovipera
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Re: Enhydris chinensis - Chinese Water Snake

Post by Viridovipera » June 19th, 2010, 12:49 pm

It's Asian watersnake madness on this forum! ...I love it! What a cool snake!

-Alex

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Mike VanValen
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Re: Enhydris chinensis - Chinese Water Snake

Post by Mike VanValen » June 19th, 2010, 3:03 pm

Again, awesome genus. Congrats!!!

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Marc Dubois
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Re: Enhydris chinensis - Chinese Water Snake

Post by Marc Dubois » June 19th, 2010, 4:31 pm

Interesting species !

With their aquatic adaptation, they have eyes on the top of their head and they look like Eunectes (anaconda).

Thanks for sharing Hans.

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Re: Enhydris chinensis - Chinese Water Snake

Post by Jason_Hood » June 19th, 2010, 5:50 pm

Hans, that was a thoroughly enjoyable post yet still very educational. Great job as always, keep em coming!!

Jason

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Hans Breuer (twoton)
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Re: Enhydris chinensis - Chinese Water Snake

Post by Hans Breuer (twoton) » June 19th, 2010, 6:56 pm

Thanks, guys!
It seems a shame to photo on wood with so many gorgeous flowers and plants around
The lilies are not in season now, there are but a bunch of dried-up leaves in the water. Also, the banks of these ponds are very narrow and even steeper, making it almost impossible to kneel down for photos. And the snake was so tiny it would have looked lost among the large plants. Enough excuses? :-)

The venom is enough to create any reaction from mild itching to considerable swelling. Gloves are in my pack from now on....

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