There are more than 1,000 species of sharks and rays, with new species discovered every year. Through their evolution, sharks have shaped our oceans into the rich habitats we know today. As apex predators, sharks play an important role in the ecosystem by maintaining the species below them in the food chain, helping remove the weak and sick, and keeping the ocean and fish populations healthy. Other deadly predators of the deep, such as the box jellyfish, lionfish, and giant octopus, are also to be feared. Did you know the stonefish is the most venomous fish species to swim in our oceans? Better not get too close--it has 13 dorsal fin spines that release deadly toxins when the fish gets into threatening situations. Learn about the dwarf lantern shark, which is so small it can fit in the palm of your hand; or the whale shark, which grows up to 40 feet in length and is the largest known fish species in the oceans today; or the great white shark, the oceans' top predator and capable of chewing up dolphins and seals with its 300 teeth.