Quirks and Quarks

Cone Snails Use Insulin as a Weapon

Snails release insulin into the water to make fish hypoglycemic and easy to catch.
Cone Snail (Conus geographus) about to engulf a disoriented fish. ( Jason Biggs and Baldomero Olivera)
Cone snails are found in many tropical waters around the world. They are among the biggest snails, measuring 10 to 15 centimetres in length. They catch fish by releasing a venomous compound into the water that immobilizes the prey.

But a new study by Dr. Helena Safavi, a Research Assistant Professor in the Biology Department at the University of Utah, has identified a specialized form of insulin as one of the key elements that comprise the cone snail venom.

The insulin is absorbed through the fish gills and quickly lowers its blood glucose level. This makes the fish disoriented and easier for the cone snail to eat. It is the first reported use of insulin as a predatory weapon. 

Related Links 

Paper in PNAS
- University of Utah news
National Geographic story
The Guardian story