The Jellyfish Thread

Jellyfish are strange, unusual creatures of which we know very little but can learn much from.

Jellyfish are found in every ocean from the surface to the deep sea. Some can even live in fresh water. We are all familiar with the shape of a jellyfish (figure 1), but how about we go a little further to describe how these unique creatures function.

Figure 1: Jellyfish Body


The bell is used for propulsion and the tentacles hang below it. Each tentacle is covered with cells called cnidocytes, that can sting or kill other animals. Most jellyfish use these cells to secure prey or for defense. Some jellyfish don't even have tentacles.
Jellyfish do not have a brain or organs; they rely solely on their nervous system to detect their surroundings. The mouth of the jellyfish also acts as the anus. They need no respiratory system because their thin skin diffuses the water around it, oxygenating the body. The outer side of a jellyfish is lined with a jelly-like material called ectoplasm. A group of jellyfish is known as a "smack."

People eat jellyfish (surprise: it's the Chinese.) Scientists like to experiment with the jellyfish's bioluminescence, to study which tissue genes are expressed. As well, we all know the toxicity to humans from jellyfish. The specific species of box jellyfish, Irukandji, no bigger than your thumbnail, will kill you in minutes. Vinegar is good to use against box jellyfish stings. Surprisingly, meat tenderizer acts as a good method of treatment as well. Do NOT use urine, alcohol, or ammonia to treat it; it will encourage the release of venom in the sting.

That's all I'd like to say about jellyfish right now - feel free to add to the thread.

And now some crazy pics: