15 Facts About Jellyfish

Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile.

Jellyfish are found all over the world, from surface waters to the deep sea.

Jellyfish have been in existence for at least 500 million years, and possibly 700 million years or more, making them the oldest multi-organ animal group.

Jellyfish are not a clade, as they include most of the Medusozoa, barring some of the Hydrozoa.

Jellyfish do not need a respiratory system because sufficient oxygen diffuses through the epidermis.

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Jellyfish achieved a 48 percent lower cost of transport than other animals in similar studies.

Jellyfish are like other cnidarians generally carnivorous, feeding on planktonic organisms, crustaceans, small fish, fish eggs and larvae, and other jellyfish, ingesting food and voiding undigested waste through the mouth.

Jellyfish washed up on the beach are consumed by foxes, other terrestrial mammals and birds.

Jellyfish can detect marine currents and swim against the current to congregate in blooms.

Jellyfish are better able to survive in nutrient-rich, oxygen-poor water than competitors, and thus can feast on plankton without competition.

Jellyfish are well placed to benefit from disturbance of marine ecosystems.

Jellyfish are hosts to a wide variety of parasitic organisms.

Jellyfish are harvested for their collagen, which is being investigated for use in a variety of applications including the treatment of rheumatoid arthritis.

Jellyfish are armed with nematocysts, a type of specialized stinging cell.

Jellyfish kill 20 to 40 people a year in the Philippines alone.