This colophon was written by Linda Mui. They are related to skates and rays, differing from ordinary bony fish in having a cartilaginous skeleton that makes their bodies unusually flexible. Unlike bony fish, sharks give birth to live young, in small litters. A common misconception about sharks is that they need to keep swimming at all times. While they do need to move their fins constantly in order to stay afloat, many species of sharks like to rest on the bottom of the ocean floor.
Sharks can also sense electrical currents in the water indicating the presence of other fish.
They retain several rows of teeth, which roll outward to replace those that are lost. The whale shark, on the other hand, is a kinder, gentler shark. As a filter feeder, they feed primarily on plankton and small fish. They have distinctive spotted markings on their fins and dorsal sides. They are the largest species of fish alive today.