Crocodile Blues

The Gharial is one of the world’s most magnificent reptiles.  This 20 foot 2000lb fish-eater crocodile evolved with the dinosaurs, and its 150 million year reign in rivers throughout the world, from Spain to Japan, has made it one of the most successful species the planet has ever seen. 

Today its future hangs by a thread.  In September 2007 the Gharial was officially recognized as “Critically Endangered” by the IUCN (http://www.iucnredlist.org/search/details.php/8966/summ), meaning it was now one small step away from extinction in the wild.  Its numbers had decreased to around 200 breeding adults in only a handful of rivers in India and Nepal.

 Then in December 2007 on the Chambal River Sanctuary in northern India Gharial began dying in mysterious circumstances. The next five months saw the death of over 100 animals, or nearly 10% of the entire wild population.  And no-one had any idea of the cause.

 Since the 1970s the future of the Gharial has been championed by herpetologist and conservationist Romulus Whitaker.  

Rom is one of the world’s foremost reptile experts, and from his base at the Madras Crocodile Bank (http://www.madrascrocodilebank.org/) has done as much as anyone on the planet to save India’s threatened reptiles.  And he has been a key player in responding to this crisis.

 This film follows Rom’s progress throughout 2008.  Can his team solve the mystery of the calamitous die-off?  How successful will his attempts be to secure the safety of the species with a pioneering captive-breeding programme?  And will the Gharial in India’s other major sanctuary cope with human pressures, habitat destruction and a disasterous monsoon flood?

 With these events unfolding over the last twelve months Crocodile Blues is an urgent account of one man’s struggle to save one of the planet’s most remarkable animals.  With footage of behaviour that has never been seen before, and may never be seen again, Crocodile Blues is a wildlife documentary that matters.

CROCODILE BLUES premieres in India on Animal Planet on 2 March, Monday at 9 pm.

DON'T MISS IT!

Note: All the text and Rom's photo are taken from http://www.iconfilms.co.uk/gharial/

Ally gator or a crocodile?

Alligators are often confused with crocodiles (I don’t know how can people do that but they do). They do share many similarities but they are two different animals.

So how do you tell them apart?

Firstly, they are a different family. There are three families of crocodilians: the alligatoridae, which includes alligators and caimans; the crocodylidae, which includes the “true” crocodiles; and gavialidae, which contains only the Gharial.

Shape of the snout: Alligators (and caimans) have a wide “U” shaped, rounded snout, whereas crocodiles tend to have a longer and more pointed “V” shaped snout.

Placement of teeth: In alligators, the upper jaw completely overlaps the lower jaw. Therefore the teeth in the lower jaw are almost hidden when the mouth closes. While in true crocodiles, the large “fourth tooth” in the lower jaw fits into a constriction in the upper jaw making it clearly visible. 

 

In the top photo you can see a fourth tooth coming out from the lower jaw of a Crocodylus niloticus (Nile crocodile) and in the bottom photo you can see no fourth tooth in an Alligator mississippiensis (American alligator).

Lingual salt glands: Crocodiles and gharials also differ from alligators and caimans in having functioning salt glands on their tongue. Structurally, these are actually modified salivary glands, and while alligators and caimans also have these structures they appear to have lost the ability to use them for excreting significant amounts of salt. This makes crocodiles more tolerant to life in saline water, including sea water in some species. 

Integumentary sense organs: Both crocodiles and alligators have small, sensory pits dotted around the upper and lower jaws - take a close look on a photograph, and you'll see small, black speckles almost like unshaven stubble. These are capable of detecting small pressure changes in water, and assist in locating and capturing prey. These were originally called ISOs, or Integumentary Sense Organs, although recent research has renamed them DPRs (Dermal Pressure Receptors). Crocodiles have similar organs covering virtually every scale on their body, but alligators and caimans only have those around the jaws.

The fourth-tooth feature is one of the most reliable external differences apart from the snout shape that allow easy identification.

Now comes the interesting stuff..

“Ally” – an American alligator at the Madras Croc Bank (She is one of my favourite crocs! Such a sweetheart.) has fourth tooth like a true crocodile!

This just may be a weird case of some unusual formation of teeth structure and is not of much importance morphologically but it surely is a pretty interesting thing to happen!

Unusual coloration in Bungarus caeruleus

Bungarus caeruleus (Common Krait) is best known for its ultra toxic venom. A medium-sized member of its genus with a metallic black coloration with white transverse stripes with a white underbelly. Its metallic black color may appear dark blue in certain wavelengths of light it is from this that its Latin specie has been derived. Though it has a bad reputation as a “potential killer”, it is a very peaceful and inoffensive snake, biting only as a last resort. Behavioral differences during day and nighttime is huge in this species. It is quite inert by day and requires a great amount of harassment in order to get it to bite voluntarily. By night it is very active and will make every attempt to avoid a confrontation with human beings. 

Feeds mainly on rodents, frogs and other snakes. The prey is pursued and a lethal dose of venom injected. It is notorious for its appetite for snakes and frequently consumes other snakes including other members of the genus Bungarus. When in pursuit of rodents it often ends up in human dwellings. Also, it is a commonly found species. These characteristics make the Common Krait, most dangerous of Bungarus species. It is one of

 the “Big Four” medicinally important snakes of India. 

Coloration

Usually, the body colour varies from a dark steely blue-black to a pale faded bluish grey. It is moderately slender. Has a smooth, glossy appearance. It has large hexagonal scales running down its spine, forming a ridge. There are paired narrow white bands along the body. The bands are absent near the neck region. Young specimens may have white spots instead of bands along first one-third of body. 

A rare catch

On 1st September 2006, I got a call from a panicked resident regarding a displaced snake inside his house at around mid-night. On being asked about the size and appearance of the snake, he said “Its about a meter long and whitish in color!” 

I was amazed by the answer. Wasting no time I rushed to the site thinking of a rare specimen. I had no idea what the species might be. On reaching the site, I was stunned by my catch. It was a Common Krait! 

The specimen was so unusually colored that it would be difficult to identify the species for an amateur herper. The dorsal scales were pinkish-white unlike a typical B. caeruleus. The bands were absent through most of its body, the rest were extremely light and hard to spot. The ridge was prominent with larger scales, typical of a B. caeruleus, but was white in color instead of jet black. On getting a closer look, I discovered that the rostral, mental, supralabials, infralabials, nasals, pre-oculars, supraocular and temporals are either fully or partially white. 

I was curious to study such an unusual specimen. Thus the snake was kept in captivity where it behaved rather lethargic and inactive. This was a male measuring 101.6cms. A good size.

In a couple of days, the snake was found to be in a moult. After shedding the skin, it was found active. Also, it started accepting food. Since everything was found to be normal, the snake was released back to a forested area close to the site of capture. 

Can it be a geographical variation? 

Geographical variation has been known in snakes. Snakes are extremely adaptive animals and this feature allows them to live in varied physical conditions. Since they inhabit in varied geographic regions, they develop certain changes in their appearance to adjust and survive in different conditions. For eg. Snakes from colder regions would be rather darker in coloration as they need to consume more heat in the cold conditions.

But in case of this Krait, there is no such explanation. The snake was caught from a moderately populated semi-urban area of Ahmedabad city, where we have been regularly rescuing snakes since atleast past ten years. There has been never such a case. All the snakes of this species in this region are jet black, sometimes bluish black or dark gray, but never pinkish-white, or any similar color. Such a color variation cannot be a geographical variation as there is no data or logical explanation supporting this. 

Color variation? 

In snakes, occurrence of natural color variation is fairly common. This is definitely a case of color variation. But it is not a fulfilling answer as this color is not one of the possible occurrence of colors in a Common Krait. 

Albinism? 

Albinism is widely distributed throughout the animal kingdom. It has been found in insects, fish, amphibians, reptiles, birds and mammals. The unusual appearance of albino animals is caused by genetic faults in the metabolic system that produces melanin, a pigment that typically causes the skin to be colored brown through to black. Albinos generally cannot produce melanin and so their appearance is determined by a combination of the other naturally occurring colors in their skin. 

The variation in color was leading to the fact that the body was unable to produce black color where it should have been black. Thus, it may be concluded that this may be a case of partial albinism.

‘Playing dead’ observed in Xenochrophis piscator as a defense strategy

Checkered Keelback (Xenochrophis piscator) is a small but strong bodied snake. An excellent swimmer with a rounded head with a broad tapering snout is effectively streamlined. Its robust, stout and muscular body is capable of rapid movement. The coloration varies considerably but it is often olive brown or olive green dorsally and pale brown or white underneath. Often the dorsal coloration is accompanied by lighter spots arranged in a checkered pattern.

Behavior: A very active snake usually active by day but it may hunt frogs by night. It has a very vicious temper and will strike repeatedly without hesitation the instant it senses that it cannot escape its challenger. Often it will keep hold until its jaws have to be forced apart in order to disengage. It is semi aquatic in habit and seldom ventures beyond the vicinity of water. If chased over long distances it may even jump clear off the ground in order to escape often repeatedly.

Food: This snake as its name suggests is piscivorous, consuming frogs and tadpoles as well. This snake usually stalks its prey and grasps it with its vice-like jaws and if in a favorable position begins to swallow it immediately. Often frogs will croak for a considerable amount of time from within this snake's stomach before succumbing to its venom due to inefficient venom delivery mechanism.

On May 1, 2007, a call came in for a displaced snake from Sola crossing in Ahmedabad city. The snake was hiding in a pile of stones. It was a Checkered Keelback. While we were returning, we were called back for more snakes. One by one, 13 hatchlings were caught. Clutch of hatched out eggs was also discovered. Everything was collected from the same pile.  75 eggs counted. 5 of them were ‘failed’ eggs, showing a high success rate. I assume that the female (it was later sexed in the rescue center) was the ‘mother’ and was guarding the eggs. The hatchlings were a day old as the eggs had not yet dried out fully. As the hatchlings started coming out, the mother must have also come out.

In the evening, the babies and the mother were taken out for a photo session. The mother, as expected, snapped, but only once. Then suddenly, she started behaving oddly. She started dying!!! I could not make out if she was actually dying or mimicking. Then she let out a very foul smelling ‘substance’ from her anal gland. Now I could link up the defense strategy.

(And she did it every time, when handled!!!) 

Baby brown snakes (Storeria dekayi) are the latest addition to the long list of animals that practice some form of the strategy scientists call extreme immobility also known as 'Letisimulation'. Gerald, a physiological ecologist at Miami University in Oxford, Ohio, described his findings in August at the annual meeting of the Animal Behavior Society.

In the U.S. Hognosed snakes, genus Heterodon are well known for letisimulation. For many years, it was thought that letisimulation, was an inherent behavioral trait. Since these snakes feed almost exclusively on toads, it was later discovered that the accumulated toxins ("Bufonitoxins") located in their Parotoid Glands had somehow interacted w/ the snake's physiology, so when the snake is disturbed or otherwise bothered, these built-up toxins would cause the behavior of "Playing Dead" 

The list of animals that play dead includes 21 snake species but I have never heard or read about a Xenochrophis piscator playing dead… 

"So  question arises: Could a snake sp. "evolve" a behavioral trait, outside of a physiological response (or, conversely, "inside" a behavioral response)?" - rightly commented by Harry A. Shankman, a herper in U.S.