Nature - Vicious Beauties: The Secret World of the Jellyfish

At the mere mention of the name jellyfish most of us imagine shapeless, rubbery and even disgusting creatures. In any case theres something we do not wish to touch. It isnt until we see them under water that they transform into graceful beings. In the course of evolution jellyfish have developed unbelievably clever skills and have conquered every habitat in our oceans. To protect themselves theyve developed weapons that can also become dangerous to humans. Most jellyfish are not a threaten species. Among the large family of jellyfish, the Box jellyfish is the most dangerous, closely followed by the Siphonophorae - the Portuguese man o war. For most of us the word jellyfish evokes negative feelings. The term medusa is more appropriate and it gives a feeling of mysterious and dangerous beauty. In this documentary Dr. Gerhard Jarms will be introducing us to the unusual life-cycle of these animals. In reality jellyfish are smooth, soft and what is even more interesting their history goes back 500 million years. During this time they have developed the most fascinating shapes and most interesting lifestyles. They live both in the deep sea and on the coastline. If we ignore for a moment the massive influxes of medusae on the coasts of the North Sea and Baltic Sea from time to time, the oceans are not necessarily packed with medusae, even some images make it look that way. Where do medusae come from? How and where do they reproduce? The life-cycle of jellyfish or medusae is characterized by a shift from one generation to the next and by a change between the sessile and the free swimming states. The gelatinous animals consist of 98% water. The life-cycle of a medusa can be from one to thirty years depending on the species. During this time they can grow up to 200 times their initial size.