A similar process causes human victims of cobras to suffer skin and tissue damage, often permanently debilitating them. Despite the damage they cause, these toxins are not as potent as neurotoxins that attack the nerves.
Why do snakes that already have deadly neurotoxic venom evolve less lethal cytotoxins? A team of 26 scientists from five countries sought the answers in a new study. By tracing the ancestry of cobras and using statistical models, the researchers discovered that cytotoxins evolved after cobras developed hoods.
Despite the name, king cobras are not close relatives of cobras. They also independently evolved to spread their hoods and sit upright, facing their antagonists.
Puffing up to look large is a common defence mechanism in the animal world. Soon afterward, the venom of cobras and king cobras developed cytotoxins, say the researchers. In cobras, the tissue destroyers are tiny peptides called 3-finger toxins. King cobras developed L-amino acid oxidase to perform the same job.
By opting for different lifestyles, a few African species like the water Naja annulata , tree Naja goldii , and burrowing cobras Naja multifasciata opted out of this defence strategy and lost their ability to hood.
Consequently, the cytotoxicity of their venom dropped. The Malayan population of king cobras, with a bright orange throat, has the highest cytotoxicity of king cobras tested in the study.
Credit: Kevin Messenger. What if the hooding bluff fails to deter? The most recent ancestor of cobras and rinkhals was probably a drab snake that could hood. Like the Egyptian cobra Naja haje , its hood may not have had any markings and its venom was possibly moderately cytotoxic. When confronted, the ancestor perhaps behaved like its modern day lookalike — fleeing after striking nervously. Three clans of closely related snakes — African cobras, Asian cobras, and rinkhals — developed a new weapon as plan B.
They fine-tuned their venom delivery kit so they could shoot a fine jet of venom from a distance at the eyes of their assailants. The opening in the fangs of these snakes became narrow and migrated from the tip to squarely face the front, the better to target the eyes.
Their venom became less viscous for greater reach. The snaked do not actually spit the venom; they contract their venom glands with powerful muscles that force the venom out through a pair of holes at the tips of the fangs. John Lindell has written articles for "The Greyhound Review" and various other online publications. A Connecticut native, his work specializes in sports, fishing and nature. Lindell worked in greyhound racing for 25 years. Types of Cobras.
Identification of Snakes in Georgia. What Is the Life Cycle of the Cobra? Aggressive Snakes in Texas. How Dangerous Are Caribbean Scorpions? Types of Dangerous Spiders. How to Identify a Cottonmouth Snake. Georgia Oak Snakes. Body Parts of a Crocodile. Cobras may hiss loudly at predators and other threats, and some species also spit. Cobras reproduce by laying eggs. Females typically lay 20 to 40 eggs at a time, which incubate between 60 and 80 days.
Wild boars and mongooses are known to steal cobra eggs. The mongoose is the best-known enemy of the cobra. According to Cobras. Cobras are also threatened from other snakes and humans. Cobras are typically opportunistic hunters, chowing down on whatever prey comes their way. Often, they eat birds, small mammals, lizards, eggs, carrion and other snakes.
They slither through the wilderness silently, following their prey until they are ready to attack. According to the San Diego Zoo, most cobras hunt at dawn or dusk, though some species forage during the heat of the day. Like other snakes, cobras have a very slow metabolism that allows them to go for days or even months without feeding.
Fortunately, antivenin is available and sometimes lives can also be saved with the use of an artificial respirator. Symptoms from a neurotoxic cobra bite can include problems with vision, difficulty swallowing and speaking, skeletal muscle weakness, difficulty breathing, respiratory failure, vomiting, abdominal pain, necrosis, and anticoagulation. According to the University of Michigan , human victims may stop breathing just 30 minutes after being bitten by a cobra.
Some cobras, including all spitting cobras, have cytotoxic venom that attacks body tissue and causes severe pain, swelling and possible necrosis death of cells and tissue.
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