print
- Compass jellyfish, foto fitis, sytske dijksen
Jellyfish
Jellyfish are coelenterates which spend most of their lives as free bodies floating with the current. They can only actively move a limited amount by contracting their bell-shaped hood. Because they cannot swim against the current, they are categorized as zooplankton. A jellyfish is a simple animal, consisting for 98% out of water.
- Species
- Rhizostoma octopus, foto fitis, sytske dijksen
The number of jellyfish worldwide continues to increase. This is partially due to the fisheries. Fish and other enemies of the jellyfish are caught in fish nets, whereby fewer jellyfish are consumed.
There are a number of jellyfish species found along the Dutch coast. For example: the moon jelly, blue jellyfish, the lion's mane jellyfish, the compass jellyfish and the rhizostome jellyfish. The sea gooseberry is not a jellyfish, but forms a separate animal group. Sometimes, you can also find animals that resemble jellyfish but are a different animal group, such as the by-the-wind sailor. - Life cycle of the jellyfish
- Moon jellyfish, juvenile, foto fitis, sytske dijksen
Jellyfish spend the most important part of their life as a free-floating animal. However, they begin their life attached to the ground, as a polyp. Male and female specimen simultaneously emit their reproduction cells. The fertilized egg cell does not produce a jellyfish as found on the beach, but a larve which attaches itself to a hard surface. Small jellyfish eventually evolve from these polyps, which release themselves when circumstances are favorable. From the moment the young jellyfish break off from the polyp, it develops quickly and sways independently in the water.
All of the North Sea jellyfish species grow no older than a year.
WWW
See also
Info
Copyright Ecomare
