We've all seen them. Those wonderful jellyfish displays at public aquariums. At least, I sure hope you've had the chance to see them. They are beautiful, graceful, soothing, and most of all super cool. Jellyfish tanks are a great conversation piece, a great draw for marine life, and serve as a perfect example of aquatic husbandry and success. Efforts to learn about jellyfish life, care, and requirements has now culminated with the ability for home hobbyists to keep, raise, and even breed these amazing animals.
What is a jellyfish?
Jellyfish are a group animals within the phylum Cnidaria. Cnidaria is the phylum that contains "stinging animals" which use nematocysts to capture pretty. There are around 10, 000 species in Cnidaria, nearly all living in marine waters. These animals morphologically develop into a sack within a sack. This body lacks basic organs like heart, brains, kidneys, etc. They do possess a couple important items including a digestive sack (stomach) and stinging cells called nematocysts. This phylum contains all the anemones and corals, which can be very similar to jellyfish. Jellyfish are very similar to anemones. Looking at their life cycle you can see that they go through the same development and processes, only they spend a different amount of time in each stage. I like to use the analogy of caterpillars and butterflies. A species of butterfly may be able to live for many months as a caterpillar and then following metamorphosis spend just a couple days as a butterfly. On the other hand, a butterfly may spend just a couple days as a caterpillar, but then spend several months as a butterfly. This is very similar to jellyfish and anemones. Jellyfish have a life cycle that basically includes the male and female system of spawning, larvae, settled polyps, juvenile medusa stage, and adult medusa. The adults are the free floating large medusa stage, which is what most people think of when you hear the word jellyfish. These medusas are usually one gender and they will spawn with other jellyfish sometimes releasing eggs and sperm into the water column. At other times the male will release sperm, which the female collects and uses to fertilize the eggs she is holding. The fertilized eggs begin to develop and eventually become free-swimming larvae. These larvae settle onto a substrate and grow into polyps. The polyps can grow and spread and develop in an asexual manner for several weeks. If conditions are right, these polyps bud off and asexually produce little jellyfish which are called ephyra. The ephyra are roughly 4 millimeters across and swim through the water and eventually grow into larger...
Fishes of the Open Ocean: A Natural History and Illustrated Guide
Book (University Of Chicago Press)
Thanks for that the other thing that chaps me2010-06-06 11:17:26 by Sample1
Is no one seems to have any concern or anger that there are rivers of oil streaming miles through the strata of water from the ocean bed on upwards.
It's as if only the "coast" matters, not the marine life out in the sea be it jellyfish, zooplankton, and other pelagic wildlife.
It's like, out of sight, out of mind.
I live in Alaska, we still have oil 20yrs later on those beaches if you dig down a foot. And Exxon's spill was likely half the size. A *minimum* 35 thousand birds were killed by Exxon (likely a gross underestimate). Not to mention a thousand otters, and all the whales, porpoises and other critters
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