Cobras' bright coloring and ability to spread their hoods evolved to warn predators, avoiding the need to use their venom. Image (C) Giuseppe Mazz

Among African Cobras, Fry reports in Toxins, spitting species have more powerful venoms than their non-spitting cousins. Nevertheless, even the non-spitters have defense-specific venom. Among Asian cobras, there is no relationship between spitting capacity and the strength of the venom.

Fry told IFLScience the capacity to spit gives a snake an incentive to make its defensive venoms more powerful, but that the Asian snakes had already gone as far as they could go with the strength of their defensive venoms when they developed spitting. Any further refinement would have been at the expense of their prey-controlling molecules. Those African cobras, on the other hand, on evolving spitting, still had room to improve the potency of their new long range weapon.

Meanwhile king cobras, which despite the name are not true cobras, never developed the capacity to spit because their venom molecules are too large to penetrate the eyeballs, a demonstration of the contingency of evolution.

“Globally, snakebite is the most neglected of all tropical diseases and antivenom manufacturers are leaving the market,” Fry said. Fry's work demonstrates the challenge of making an anti-venom that will work against different forms of cobra venom, but may also help achieve that goal.

 Although most venoms kill healthy and cancerous cells equally, Fry told IFLScience somewhere among the vast array of cell-killing molecules he has explored it is likely there is one that is more selective, and could eventually be used to stop tumors while having less impact on healthy cells than existing chemotherapies.

Expanding the hood allows a cobra to look more fearsome, like a human puffing up their chest, while coloring says "don't tread on me". Gowri Mallapur

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