Natures wonders: fanged fish use venom to escape (Introduction)

by David Turell , Friday, April 28, 2017, 21:59 (2764 days ago) @ David Turell

Just like snakes, but this venom doesn't cause pain, it drops blood pressure:

http://www.the-scientist.com/?articles.view/articleNo/49305/title/Behavior-Brief/&u...

"When eaten, a poisonous fang blenny (Meiacanthus) will bite the inside of its predator’s mouth, injecting a venom that has potent hypotensive effects. This can cause blood pressure to drop by nearly 40 percent, according to a study published earlier last month (March 30) in Current Biology.

“'If you had such a big crash in blood pressure, you would immediately feel faint and dizzy,” coauthor Nick Casewell of the Liverpool School of Tropical Medicine in the U.K told The New York Times. “We don’t know that fish get faint or dizzy, but it’s extremely likely such a large drop would impact coordination and swimming ability.”

"Casewell and colleagues analyzed the venom of 11 fang blenny species and discovered three main toxins: enkephalines (opioid-like molecules), neuropeptide Y (molecules that cause blood pressure to plummet), and phospholipase A2 (enzymes that promotes inflammation). “What’s really unusual are these opioid-like neuropeptides called enkephalins, which don’t induce pain,” Casewell told New Scientist. “Most animals that produce venom use it to inflict pain, yet we found no evidence of that with the blenny venom.” Casewell said he thinks that these molecules act together with neuropeptide Y to exert powerful hypotensive effects, according to New Scientist.

"Not all fang blenny species are venomous, but many nonvenomous fish, such as Plagiotremus, mimic the appearance and behavior of poisonous ones. “In some places, Plagiotremus is very cryptic, hiding in holes and waiting for its prey to swim by, at which point it darts and takes a bite,” Luiz Rocha of the California Academy of Sciences who was not involved in the study, told The Atlantic. “But when Plagiotremus mimics the venomous Meiacanthus, it doesn’t hide.'”

Comment: Two evolutionary problems: how did the fish find this combination of proteins when they developed as a species? Also the proteins had to be onboard from the beginning or the fish would not have survived. Further, the fish has to have a setup which protects itself from these proteins, or they would be in constant trouble. Looks designed.