Cone Snails Disable Fish With Weaponized Form of Insulin

Posted on January 19, 2015

A cone snail trying to capture a fish to eat

Scientists from the University of Utah have discovered that snails use a weaponized form on insulin to disable fish before eating them. The photograph above shows a cone snail attempting to capture a fish. The snail releases its specialized weaponized insulin and neurotoxins into the water in the direction of the fish.

The combination of insulin and neurotoxins results in hypoglycemic, sensory-deprived fish that the cone snails can easily engulf using their large, stretchy mouth parts. The snail injects paralytic toxins into the fish after it has engfulfed the fish.

The scientists injected a synthetic form of the snail insulin into a zebrafish and found the blood glucose levels in the fish plummeted. They also found that the insulin disrupts the ability of fish to swim when they are exposed to it through water contact. The scientists theorize that the mix of venom toxins enables predatory cone snails to "disable entire schools of swimming fish with hypoglycemic shock."

Baldomero M. Olivera, professor of biology at the University of Utah and senior author of the study, says in a statement, "This is a unique type of insulin. It is shorter than any insulin that has been described in any animal. We found it in the venom in large amounts."

There are other types of fish-eating cone snails that attack fish with harpoon-like organs. The weaponized insulin was not found in the venom of these types of cone snails. The fish insulin was also not found in cone snails that eat worms and molluscs.

The study was published the journal, Proceedings of the National Academy of Sciences.

Photo: Jason Biggs and Baldomero Olivera at the University of Utah