The evolution of super-toxic flesh-eating venom in spitting cobras

Of the nearly 4,000 species known to science, about 600 are venomous, and the vast majority of these use venom to immobilize and digest their prey. But some cobras have independently evolved the ability defend themselves by spitting super-toxic flesh-eating venom at predators. New research reveals the genetic basis of these adaptations, and the driving force behind them.

Tiger moths jam bat sonar

BATS use sonar, or echolocation, to navigate complex environments, and also to forage and then accurately pinpoint the flying insects on which they prey. Insects in turn have evolved various counter-measures to evade capture. Some species have ears which are in tune to the echolocation signals, while others are capable of performing complex evasive flight maneuvers in response to the clicks produced by attacking bats.

Tiger moths have evolved the ability to produce ultrasonic clicks in response to attacking bats. However, the function of these clicks was unclear, although decades of research has led to a number of hypotheses. The clicks may act to startle attacking bats, or they may be an acoustic signal which warns them that the moth is unpalatable. A study published in today’s issue of the journal Science provides the first clear evidence for the third hypothesis – that the clicks interfere with (or “jam”) the bats’ echolocation signals.