The animal can then pull its prey into its mouth.Īlthough most jellyfish are not dangerous to humans, a few are highly toxic, such as the Lion’s mane jellyfish (Cyanea capillata) also known as the Deep Spiderfish.Ĭontrary to popular belief, the menacingly infamous Portuguese Man o’ War (Physalia) is not a jellyfish but a colony of hydrozoans (organisms that are related to jellyfish and corals and belong to the phylum ‘Cnidaria’). Upon contact, the filament rapidly unwinds, launches into the target and injects toxins. Each nematocyst has a ‘trigger’ paired with a capsule containing a coiled stinging filament armed with exterior barbs. Most jellyfish have tendrils or oral arms coated with thousands of microscopic nematocysts (a type of venomous cell). They do this by rhythmically opening and closing their bell-like body. Instead, they move so as to create a current forcing the prey within reach of their tentacles. Most jellyfish are passive drifters and slow swimmers, as their shape is not hydrodynamic. Jellyfish feed on small fish and zooplankton that become caught in their tentacles. Jellyfish lack basic sensory organs and a brain, however, their nervous systems and rhopalia (small sensory structures) allow them to perceive stimuli, such as light and odour and enable them to respond quickly. Instead, they have eight highly-branched oral arms. Others, such as Jellyfish in the Order ‘Rhizostomae’ have neither tentacles nor other structures at the bells edges. Most jellyfish use these cells to secure prey or for defence. The body of an adult jellyfish consists of a bell shaped hood enclosing its internal structure and from which tentacles are suspended.Įach tentacle is covered with cells called ‘cnidocytes’ (a type of venomous cell unique to the phylum ‘Cnidaria’), that can sting or kill other animals. Each cluster includes a pair of eyes with a sophisticated lens, retina, iris and cornea, although without a central nervous system, scientists aren’t sure how they process what they see.Jellyfish come in a huge range of forms, however, their body construction is reasonably similar. They also have eyes grouped in clusters of six on the four sides of their bell. They have developed the ability to move rather than just drift, jetting at up to four knots through the water. Highly-Advanced Adaptationsīox jellies are highly advanced among jellyfish. Each tentacle has about 5,000 stinging cells, which are triggered not by touch but by the presence of a chemical on the outer layer of its prey. Up to 15 tentacles grow from each corner of the bell and can reach 10 feet in length. They are pale blue and transparent in color and get their name from the cube-like shape of their bell. Range and Appearanceīox jellies, also called sea wasps and marine stingers, live primarily in coastal waters off Northern Australia and throughout the Indo-Pacific. Survivors can experience considerable pain for weeks and often have significant scarring where the tentacles made contact.
It is so overpoweringly painful, human victims have been known to go into shock and drown or die of heart failure before even reaching shore.
A BOX JELLYFISH SKIN
Their venom is considered to be among the most deadly in the world, containing toxins that attack the heart, nervous system, and skin cells. The infamous box jellyfish developed its frighteningly powerful venom to instantly stun or kill prey, like fish and shrimp, so their struggle to escape wouldn’t damage its delicate tentacles.
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