Venom! Nature’s Deadly Arsenal
Medo pit viper Trimeresurus medoensis
Photo: Ashok Captain.
The venom apparatus is most highly developed in snakes. Snakes can be classified based on the structure of their fangs (venom injectors). Among snakes, vipers possess the most advanced biting apparatus, called solenoglyphs. They have very long fangs (each with a canal), which when not in use are folded along the roof of the mouth. The strike is rapid with the fangs being thrown forwards and the snake withdraws without chewing, unlike opisthoglyphs (whip snakes) and proteroglyphs (cobras). The bite of this beautiful snake is not fatal, but the excruciating pain can last for up to two weeks. Though arboreal, the local Lisu tribals in the rainforests of Arunachal where T. medoensis is found say that it moves about on the ground at night in search of frogs.
Spider (Class Arachnida)
Photo: Ashok Captain.
All spiders are venomous. They are predators that feed on the tissues of other animals, which must first be subdued or killed. Venom is injected by means of a pair of hollow fangs. A spider stabs rather than stings or bites. Its mouthparts are designed for sucking out the juices of its prey; it cannot chew solid food and the victim’s body is eventually discarded as a dry husk. The primary use of the spider’s fangs is to secure food but they also have a defensive function. If the predator is itself in danger, it can turn its weapon on its attacker. This spider was photographed under a stone on the banks of the Noa Dihing river in Arunachal Pradesh, raising its forelegs in a threat display to show its red ‘armpits’.
The natural world uses its own chemical warfare. Tarantula spiders, scorpions, spitting cobras, poison arrow frogs, chameleons, millipedes and a number of other creatures use potent toxins as a form of self-defence or to paralyse their prey. The toxins penetrate tissues, membranes and receptors in their victims, causing heart failure, the breakdown of the central nervous system or even blood vessel walls. Other toxins are less potent and only cause temporary muscle weakness or neuromuscular paralysis.
Scorpion Mesobuthus tamulus tamulus
Photo: Ashok Captain.
Scorpions are eight-legged relatives of spiders. They live in relatively warmer climes and are particularly abundant in dry, desert regions. They possess a pair of pincers or pedipalps, which are harmless and used for tearing up food. The sting lies in their tails. Timid creatures, they almost invariably give off a warning sound before attacking. Mouthparts rasp against the roof of the mouth, legs are rubbed together or the tip of the tail is scraped against the abdomen. Their tail then whips forward to attack. The curved sting is connected to two large venom glands, which pump a neurotoxin into the victim. The venom of some species is more powerful than that of many venomous snakes. The symptoms are like those of strychnine poisoning. Apart from the pain, there is vomiting, sweating, shivering and difficulty in speech. In the worst cases, the victim will froth at the mouth and nose and may convulse before dying.
Wasp Polistes sp.
Photo: T.N.A. Perumal.
The venom of wasps contains histamine, a substance that occurs naturally in the human body. Injection into the skin results in a ‘nettle-rash’-redness, blistering and itching. Larger doses may cause difficulty in breathing. Another component of wasp venom is hyaluronidase, an enzyme which dissolves the cement that binds tissue cells together, thereby allowing the venom to spread. Other pain inducers include 5-hydroxytryptamine and kinins. Cold compresses and soothing lotions alleviate mild stings but severe stings may require medical attention and the injection of antihistamines, epinephrine or calcium lactate.
Lionfish Pterois volitans
Photo: Fritz Bachmayer.
Danger lurks in the body of the beautiful and bizarre lionfish, also called dragonfish, turkeyfish, firefish or zebrafish. Eighteen of its many spines carry venom. When disturbed, the lionfish turns to present its venomous spines. A sting is excruciatingly painful for several hours but most victims recover. The bright colours of the fish serve as a warning to potential predators. Incredibly, the poison is effective even after the fish dies, a fact that many fishermen have discovered to their extreme discomfort!
Sanctuary Asia, Vol. XXII. No. 3, June 2002.