OLogy Cards > smalltooth sawfish

smalltooth sawfish

The body of a sawfish may look like a fish, but its long, flat snout sets it apart. Rimmed with razor-sharp points, this "saw" is a dangerous weapon for hunting prey and defending from predators. It can also be used to dig in sand looking for shellfish to eat. The sawfish's snout is covered with special sensory organs that detect electric signals produced by other animals. This ability, called electroreception, is like a "sixth sense" that helps the sawfish track prey, even in dark, muddy rivers and lagoons.

Stats

Scientific Name: Pristis pectinata
Habitats: shallow, coastal tropical waters
Diet: fish and crustaceans
Size: 18-25 feet (5.5-7 m)
Weight: 770 pounds (350 kg)
Lifespan: 25-30 years
Status: endangered
Cool Fact: The saw of a largetooth sawfish may have more than 40 sharp "teeth." But as with all sawfish, they're not really teeth. Its real teeth are in its mouth under its snout!

Story

Super-Sensitive Saw
Did you know that all living things produce weak electrical signals?

We can't detect them, but sawfish can. They have hundreds or thousands of tiny sensory organs called ampullae of Lorenzini.

These "electrosensors" are pores in the skin. Each pore leads to a canal filled with gel that conducts electricity. Sensory cells at the bottom of the canal respond to changes in voltage. Then nerves carry this signal to the fish's brain.

Most of its electrosensors are found on the top of its snout or saw. As the sawfish hunts, it "scans" the water for electrical activity by waving its snout back and forth.

Stumper

Electricity travels best through:

air

soil

water

Correct!

Water conducts electricity well. This is why electrosensing is found in aquatic animals like sharks, sawfishes, and rays.

Stumper

Electrosensing isn't used just for tracking prey. Fishes also use electricity to:

communicate

shock prey

both of these

Correct!

Some fishes like the African elephantfish communicate by sending and receiving electric signals. The electric eel can emit enough electricity to paralyze its victim!

Fact or Fiction

Sawfish is a type of shark.

Fact

Fiction

Sawfish may have a shark-like body, but are actually a type of ray. All rays have gill slits on the bottom of their bodies.

Image credits: main image, Forrest Samuels (CC BY-SA 2.0).

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