A paper from Thailand has recently hit the herpetological headlines. We all know that snakes swallow their prey whole. They do not dismember their prey in order to swallow pieces, except when pieces, like the limbs of crabs or the tails of lizards fall off. That rule has just found a gruesome exception in the Small-banded Kukri Snake, Oligodon fasciolatus. After sometimes epic battles and the shedding of blood, this snake has been observed to cut a hole into the body cavity of the toad Duttaphrynus melanostictus and then cut out and eat the internal organs. During the attacks, the toads produced copious quantities of toxins from the skin and the parotoid glands on the neck; these caused the snake, when hit in the eye, to break off but then resume its attack.
Here is a description of the first time the authors observed this behaviour:
A large adult female O. fasciolatus was observed eating parts of an adult D. melanostictus. The toad was dead upon the observers’ arrival, but the soil around the two animals was bloody, indicating there had been a fight which eventually killed the toad. The snake used its enlarged posterior maxillary teeth to slit through the left side of the abdomen just underneath the left front leg. Its head was swung from side to side as it managed to cut through the skin of the toad. Slowly the snake inserted its head into the left side of the toad’s abdomen and subsequently it pulled out organs like liver, heart, lung and part of the gastrointestinal tract (at least the full stomach and full small intestines). During the process of retraction, the head was moved in different directions with a partly open mouth, allowing the teeth to cut the organs into smaller pieces which were then swallowed.
Cutting a hole to eat the internal organs was not the only way of eating toads because the authors saw a smaller toad being swallowed whole in the conventional manner.
The new paper raises intriguing questions about both predator and prey. For example, is this method only employed against toads with high concentrations of toxin in the skin. In other words, as a way of avoiding the ingestion of toxins? Or is it used more widely against other animals that are too big to swallow?
The snake in question is a member of a genus of about 80 species that range from the Middle East to Indonesia. Do any of the other species employ the same method to prey on toads or other animals? In that respect, it is perhaps important that the Kukri snakes bear that name for a reason: the teeth towards the posterior of the upper jaw are large and shaped like a kukri, the knife carried by and forming the cap badge of the venerated regiment of the British Army, the Royal Gurkha Rifles. As every schoolboy knows the blade is sharp, very sharp. People who have handled kukri snakes have found that bites can be deep and much blood may be shed.
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| From Coleman et al. |
In some species of Oligodon, the large teeth have been implicated in their feeding on the leathery eggs of reptiles which they cut open and then put their head inside to swallow the contents. I don’t think anybody had envisaged that they may use the same technique on live prey.
I am now wondering if the toads of the same species as the one observed being eaten alive in Thailand that are widespread in Hong Kong suffer the same fate in the coils of two species of Oligodon that are found there. One is the Taiwan Kukri Snake, O. formosanus, the species used to study in detail it method of opening eggs. It is said to also eat birds’ egg, frogs, lizards and small rodents. The other is the Golden Kukri Snake, O. cinereus, which is said to eat insects and spiders. I am not sure where that information originally came from but I do now wonder if the one we were lucky enough to find—they are uncommon—in 1968 at about 500 metres altitude just off Route Twisk in the New Territories would turn its nose up at the chance to open up a passing toad and eat it in bits from the inside.
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| Golden Kukri Snake. Hong Kong early 1968 |
Bringsøe H, Suthanthangjai M, Suthanthangjai W, Nimnuam K. 2020. Eviscerated alive: novel and macabre feeding strategy in Oligodon fasciolatus (Günther, 1864) eating organs of Duttaphrynus melanostictus (Schneider, 1799) in Thailand. Herpetozoa 33, 157–163 DOI 10.3897/herpetozoa.33.e57096
Coleman K, Rothfuss LA, Ota H, Kardong KV. 1993. Kinematics of egg-eating by the specialized taiwan snake Oligodon formosanus. Journal of Herpetology 27, 320-327.
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| Kukris on the cap badge of the Royal Gurkha Rifles https://en.wikipedia.org/w/index.php?curid=955766 |
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