(Rhincodon typus), gigantic but harmless shark (family Rhincodontidae) found worldwide but mainly in the tropics. The largest of living fishes, it often grows to about 9 m (30 feet) long and reportedly may reach twice that. It is gray or brown with a pale undersurface and is distinctively marked with small spots and narrow vertical lines of yellow or white. The whale shark has tiny teeth and feeds on plankton and small fishes. A sluggish animal, it generally swims slowly near the surface and has been hit by ships.