Bloodworms are not for the faint of heart. These fleshy looking sea tubes may look harmless from a distance, but don’t be fooled.

Bloodworms (also known as “bristleworms” of the genus glycera) are carnivores that burrow deep into the mud along the ocean floor to grab prey and competitors with their fearsome jaws, which are partly made of copper – and laced with crippling venom.

Even scientists who study these creatures for a living don’t think much of mosquito larvae.

“These are very unpleasant worms because they are cranky and easily provoked,” says biochemist Herbert Waite of the University of California, Santa Barbara.