Natures wonders: Snake venom from eaten prey (Introduction)

by David Turell , Tuesday, February 25, 2020, 21:25 (1731 days ago) @ David Turell

The snakes have actually switched prey with the same toxin obtained:

https://www.sciencedaily.com/releases/2020/02/200224165311.htm

"Such is the case with most snake species of the Rhabdophis genus. Commonly called "keelbacks" and found primarily in southeast Asia, the snakes sport glands in their skin, sometimes just around the neck, where they store bufadienolides, a class of lethal steroids they get from toads, their toxic prey of choice.

"'Scientists once thought these snakes produced their own toxins, but learned, instead, they obtain it from their food -- namely, toads."

"In a surprising twist, Savitzky and colleagues ... reports a species group of the snakes, found in western China and Japan, shifted its primary diet from frogs (including toads) to earthworms.

"The earthworms don't produce the toxins; instead, the snakes also snack on firefly larvae, which produce the same class of toxins as the toads.

"'This is the first documented case of a vertebrate predator switching from a vertebrate prey to an invertebrate prey for the selective advantage of getting the same chemical class of defensive toxin," says Savitzky, professor in USU's Department of Biology and the USU Ecology Center.

"Given the distant relationship between toads and fireflies, he says, the dramatic dietary shift most likely involved a chemical cue shared by the toads and fireflies; perhaps the toxins themselves.

"'This represents a remarkable evolutionary example of adaptation to compensate for the absence of defensive compounds following a shift to a new class of prey," Savitzky says."

Comment: This involves several needed actors, so the authors suggesting a 'chemical cue' helping with the switch evidences their surprise as to how this happened. Also luck or design can be considered.