It has been widely known that sharks have a special sensory organ on their heads, called the ampullae of Lorenzini, which enable them to detect the very weak electrical fields that prey emit when they swim or bleed.

But now scientists have found that a gel-like substance plays a big role in this process known as electroreception, explaining why sharks pursue bloody victims, even when other easy target´s prey is around, and the gushing blood obscures the shark´s vision and smell.

The gel, which sits in the skin pores that are the openings to the sensory ampullae of Lorenzini, contains various proteins and salts similar to mucus only with a jello-like consistency, said R. Douglas Fields, lead author of the new report.

With this gel, sharks can detect the strong electrical field produced by bloody salts,” explains Fields.

Skin membrane cells sense electricity, causing positively charged calcium ions to rush in. The charge moves through the gel before reaching nerves that send the electrical signals to the fish´s brain.

It was previously believed that the gel served as a semiconductor, generating electricity in response to temperature changes, but the new study demonstrates that the gel is nothing but a conductor that allows electrical signals to move from the membrane to the brain.