Lesson 1
Dots on a shark's snout
Look closely at a shark's snout and you will see lots of tiny dark dots. Each dot is a pore, a little opening in the skin.
- Each pore leads to a tube filled with a clear jelly.
- At the bottom of the tube is a little bulb lined with sensor cells.
- Nerves carry messages from the sensor cells to the shark's brain.
Together, these are called the ampullae of Lorenzini (say "am-PULL-ee of lor-en-ZEE-nee"), named after a scientist who described them long ago.
Try thisScroll up to the 3D model and press Cut it open to see inside one jelly tube.
Lesson 2
Feeling hidden animals
Every time an animal moves a muscle or its heart beats, it makes a very tiny electric signal. This is true for fish, crabs, and even you!
The jelly in the tubes carries these signals down to the sensor cells. The sensor cells notice them and tell the brain. So a shark can find a fish hiding under the sand, even when it can't see or smell it.
Try thisPress Feel a signal to watch a signal travel down the jelly tube to the sensor cells.
Wow!The electric sense works only up close, so sharks often use it in the last moment before they catch a meal.
Lesson 3
Not just sharks
Rays, which are cousins of sharks, have the same jelly-filled pores. The platypus can sense electric signals with its bill too!
A hammerhead shark has a wide, flat head, which gives it lots of room for pores. Scientists think this may help it sweep the sea floor for hidden food, like a metal detector.
Wow!Some animals make big electric shocks instead of just sensing tiny ones. Meet them on the Electric cells page!
Quiz
Shark sensor quiz