A shark's electro-sensitive Ampullae of Lorenzini can detect 5nV/cm to home in on your ECG.
The ampullae of Lorenzini are electroreceptors found in cartilaginous fish such as sharks and rays first described by Stefano Lorenzini in 1678.
These sensory organs help fish to sense electric fields in the water. Each ampulla consists of a jelly-filled canal opening to the surface by a pore in the skin and ending blindly in a cluster of small pockets full of special jelly. The ampullae are mostly clustered into groups inside the body, each cluster having ampullae connecting with different parts of the skin, but preserving a left-right symmetry. The canal lengths vary from animal to animal, but the distribution of the pores is generally specific to each species. The ampullae pores are plainly visible as dark spots in the skin. They provide fish with a sixth sense capable of detecting electromagnetic fields as well as temperature gradients.
Sharks may be more sensitive to electric fields than any other animal, with a threshold of sensitivity as low as 5 nV/cm. That is 5/1,000,000,000 of a volt measured in a centimeter-long ampulla.
All living creatures produce an electrical field associated with muscle contractions. Sharks are able to detect and track these weak electrical signals from a considerable distance.
Read factlets by:
RSS feed
Email feed
