tangledwing:

This is a Synalpheus pinkfloydi, a newly discovered species of shrimp named for Pink Floyd. The shrimp uses a bright pink claw to create a sound loud enough to kill small fish.
Photograph: Arthur Anker/AP.

Unfortunately, that’s a myth, albeit a very common one about these guys and their relatives. Pistol shrimp like this mostly use the sound to frighten predators, and they can, in fact, create a cavitation bubble in the water that causes the sensation of an impact despite the shrimp being several inches away. It’s painful to experience up close, but not lethal for vertebrates and arthropods. They’re mostly scavengers, and the snap is to discourage predators or anything trying to get into the shrimp’s house. What CAN kill the fish is that claw snapping shut on something important, but these guys usually don’t kill anything other than, say, worms. Their legs aren’t durable enough to go around trying to kill vertebrates.