Jellyfish (Early Bird Nature Books) Describes the life cycle, habitat, behavior, and physical structure of the soft bodied sea animal that has no brain or bones. (children's book)

WHAT EXACTLY ARE JELLYFISH?

Jellyfish are semi-transparent, graceful creatures. They are only five percent solid matter and form, and the remaining 95 percent is all water!  Sea anemones and corals are related to jellyfish; they belong to the same phylum (cnidaria).

INTERESTING INFO:

Phylum:  Cnidaria (pronounced ny-DAIR-ee-ah)

Class:  Scyphozoa

Number of Jellyfish Species: ~200

Sizes: Jellyfish come in a wide variety of sizes and shapes, from the 1" thimble size Caribbean jellyfish to the Arctic Lion's Mane's jellyfish with tentacles as long as 100 feet, and weighing up to a ton.

"If I Only Had a Brain..." or a backbone, heart, bones, or blood, for that matter: Jellyfish do not have a brain, but an elementary nervous system capable of detecting and responding to light, smell and other stimuli. Being invertebrates, they lack a spine.

Habitat: Most live in shallow coastal waters, but some inhabit depths of 12,000 feet! There are also some freshwater jellyfish.

Brilliant Colors: Jellyfish colors are known for great brilliance...blue, orange, red, and more.

Polymorphism: Jellyfish can exist as two different types of species in one life time. Part of the time they can exist as polyps and part of the time as medusa.

Lifespan: Three to six months.

Locomotion: Jellyfish drift with the currents with little control over horizontal movement, although there is some ability to navigate vertically.

Sting/Venom: Poisonous, venom-filled barbs called nematocysts —in some cases thousands of them—line jellyfish tentacles. The venom paralyzes its victims, although it is usually only strong enough to paralyze small creatures. A few species, like the box jellyfish of Australia, can be very dangerous to humans.  Beachcombers should also beware of dead jellyfish (of any kind) that wash ashore, as their tentacles can still be active. 

Raising baby jellyfish isn't an easy job, but somebody has to do it. Almost unnoticeable amid a sea of artwork that covers the wall, a small door opens into the guts of the new jellies exhibit at the Monterey Bay Aquarium. It's where Bruce Upton does the essential, but not glamorous, work of raising jellyfish.
Full story...

Caution: If you or someone gets stung by a jellyfish, make sure to get them out of the water to avoid drowning. Alcohol should not be put on stings as it actually stimulates the venom.

Aggressive Jellyfish?: Jellyfish do not attack humans (they can't direct their horizontal movement), but drift into them, and humans get entangled in their tentacles.

Jellyfish belong to the phylum Cnidaria, whose members possess stinging cells that can inject a paralyzing poison into prey.  Other members of this phylum include sea anemones, sea fans, hydra and reef-forming corals.  True jellyfish fit into the species scyphozoa; most have an umbrella shaped concave body with a centrally located mouth.  The cells that line the inner part of the jellyfish body cavity secrete digestive enzymes and absorb nutrients.  The fossil record for cnidarians begins in the Pre-Cambrian (earliest) era of earth history, meaning that the direct ancestry of these creatures dates to at least 600 million years ago!

Big Red!  In the depths of the ocean lurks a huge, predatory jellyfish, recently caught in the Monterey Submarine Canyon (a 4000-meter trench off of the California coast).  The dark red creatures are 2 to 3 feet long, and roam waters that rarely get above 40 degrees Fahrenheit.  Most surprisingly, in place of tentacles, they have a few short, thick arms that may be used for feeding.   Though Big Red had been discovered and photographed a few years ago, scientists only recently obtained a specimen for study.  They currently know almost nothing about it, but hope to learn more in the coming months.  Get the details and photos at National Geographic.

These jellyfish can see, man.  The box jellyfish, known for their square-shaped bodies, are more sophisticated than most jellyfish species.  Not only can they swim better, but recently scientists discovered that 8 of their 24 eyes function extremely well.  Each eye contains a lens and a retina, providing a blurred vision that allows the animal to focus on large objects.  This form of vision works well in the near shore waters, among mangrove roots and other obstacles, that box jellyfish populate.  Read more at Science News.

Killer Jellyfish. Okay, so not only can box jellyfish see, but one species is tailor-made to attack and kill vertebrates.  The box jelly Chironex fleckeri, found off the coast of northern Australia, has perhaps the most deadly venom in the word.  Sixty-five Australians have been killed by it in the last 50 years.  While many jellyfish species float freely and feed on plankton, these predators swim fast and can kill fish and other animals with “a single flick of a tentacle”.  Their tentacles can grow to nearly seven feet long, so they are a definite danger to swimmers.  More from Natural History magazine. 

GENERAL:

• Introduction to the Cnidaria
• Aquarium Design - Jellyfish
• Sea Science
• British Marine Life Study Society - Jellyfish Page
• Neither Fish nor Jelly
• Hawaiian Lifeguard Association Jellyfish Page

JELLY-FUN

• Something's Lurking in the Sea
• Jellyfish Pictures

JELLYFISH EXHIBITS:

• Oregon Coast Aquarium - Jewels of the Sea
• Monterey Bay Aquarium
• Cabrillo Marine Aquarium
• Long Beach Aquarium of the Pacific
•  Aquarium Jellyfish Page
  

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