There are over 2,000 known species of jellyfish, such as the Lions Mane Jelly, the Moon Jelly, and the Box Jellyfish. Some, like the irukandji jellyfish, can be deadly to humans.
Jellyfish are marine creatures found in every ocean on Earth, from the freezing Arctic Ocean to the warm tropical waters of the Caribbean. They can inhabit shallow or deep waters.
Jellyfish diet mainly comprises of small fish, plankton, and other jellyfish. Some large species are known to feed on crustaceans, and zooplankton.
Several marine animals like tuna, shark, swordfish, sea turtles, and even other jellyfish are known to prey on jellyfish. Birds have also been observed feeding on them.
The lifespan of a jellyfish varies greatly by species. While some only live a few hours after reaching adulthood, others like the Turritopsis dohrnii are technically immortal.
Jellyfish do not have a brain or central nervous system, but can still respond to changes in their environment using their nerve net. They drift with the ocean currents.