Jellyfish Research

Medusozoa (Scientific Name)

Classes/Morphologies:

Cubozoa        20 species
Hydrozoa    1000-1500 species
Polypodiozoa   
Scyphozoa    200 species
Staurozoa    50 species

Freshwater jellyfish do not sting, are colourless
and less than an inch in diameter.

Evidence of existence for about 500 million years
 
Types
Box jellyfish
Flower hat jellies
Irukandji jellyfish
T. Nutricula (biologically immortal)
Aurelia (Moon jelly) (Demonstrate active ability to stay together)
Cannonball jellyfish (Harvested for culinary purposes, same as below)
Sea stings (harvested for food, toxins are harmless to humans, larger, rigid body)
Pacific Sea nettle jellyfish
Lion's mane jellyfish (One of the largest jellyfish)
Nomura's jellyfish
White-spotted jellyfish
Purple-striped jelly


Not vertebrates, or even true fish. The word 'jellyfish' is
therefore, a misnomer, and American aquarium have popularised
the use of 'jellies' or 'sea jellies'.

A 'bloom' or 'swarm' of jellyfish.

Aboral surface- The surface of the umbrella-shaped head
Proximo-distal axis- The tail
Distal end- The end of the tail

Most jellyfish do not have digestive, central nervous, respiratory or
circulatory systems. They digest using the lining of their gastrovascular
cavity. Their skin is thin enough to be oxygenated by diffusion. They have
limited control over movement, but they may utilize their hydrostatic skeleton
to contract and pulsate the bell-like body.

Jellyfish are composed of 90% water, with their 'umbrella' being comprised of
a gelatinous material known as mesoglea. They have no brains, but a loose
network of nerves located in their epidermis, which is known as a nerve net.

Some jellyfish have ocelli; light-sensitive organs that detect light and
are used to determine up from down by responding to sunlight reflected on the
water's surface.

The box jellyfish is more advanced than usual. It has 24 eyes, two of which detect
colour and it has four parallel brains, making it one of the only creatures in
existence to have a full 360 degree view. The species has an as yet unseen type of
central nervous system. Certain species of box jellyfish have been found to also
sleep on the seabed.

Jellyfish survive better in saltier waters, as iodine is essential for polyps
(larval form of jellyfish, that resemble sea anemones) to become jellyfish.
Some species reproduce by fission (splitting in half). Baby jellyfish
(which burst from polyps) are known as medusae (singular: medusa). They are
radially symmetric.

Lifespans are sporadic, ranging from a few hours to several months. One unusual
species lives for reportedly 30 years. Some jellyfish are harvested for food,
usually in Southeast Asia. Jellyfish are also harvested for their collagen.

They sting using nematocysts, also known as cnidocytes. Stings can cause anaphylaxis
and therefore, anaphylactic shock. In 2006, the Spanish Red Cross treated 19,000
stung swimmers along the Costa Brava. In 2010, 125-150 were stung by pieces of a
dead lion's mane jellyfish. In the Phillipines alone, 20-40 people are killed by
jellyfish stings.

Urine, ammonia, spirits and alcohol will encourage the release of venom when stung.
Scraping the area with a knife edge can remove nematocysts. Baking soda and water
applied with a cloth can remove venom from skin.

Jellyfish can clog cooling equipment and disable power plants, such as a blackout
in the Phillipines in 1999, and the Diablo Canyon Power Plant in Calafornia in 2010.
Jellyfish can also clog ship engines, and invade fishing nets, ruining them and possibly
crushing the fish. Jellyfish also cause trouble by consuming fish eggs as well as young
fish.

The lion's mane jellyfish is the longest animal in the world, with tentacles up to
36.5m. Nomura's jellyfish is possibly the largest species of jellyfish, with a
diameter of 2 meters.