They can weigh up to 4 tons. The shape of its snout is conical and the gill slits extend around the top and bottom of its head. Associated with the gills are structures called gill rakers. These gill rakers are dark and bristle like and are used to catch plankton as water filters through the mouth and over the gills.
Basking sharks are planktonic feeders. By swimming with their mouths wide open, they filter plankton out of the water with their long, tightly set gill rakers. The water then exits the body via the gill slits. Most of the plankton which is ingested consists of copepods and other crustaceans, fish eggs and larvae. The gill rakers are shed in the winter and are replaced the following spring.