The large mouth of the basking shark can measure over 3 feet across when open. The species swims with its mouth agape, catching plankton and other small organisms on bristles along massive gill slits, which filter as much as 1,500 gallons of water per hour during feeding.
The mouth contains hundreds of small, backwards-hooked teeth that are of little use. The short, conical snout of this slow-moving species is often seen near the surface of the water, where it feeds. Reaching more than 33 feet in length and 4 tons, it is the second-largest of all sharks, trailing only the whale shark, another filter feeder.