his article is about the aquatic animal-form. For similar animals, see gelatinous zooplankton. For
other uses, see Jellyfish (disambiguation).
Temporal range: 5050 Ma
Pacific sea nettle
See also: alpha taxonomy, Linnaean taxonomy, taxon and binomial nomenclature
The lion's mane jellyfish(Cyanea capillata) is one of the larger species of jellyfish.
A purple-striped jellyfish at theMonterey Bay Aquarium
Jellyfish belong to Medusoz
The English popular name jellyfish has been in use since 1796. It has traditionally also been
applied to other animals sharing a superficial resemblance, for example ctenophores (members from
another phylum of common, gelatinous and general
Jellyfish range from about one millimeter in bell height and diameter to nearly 2 metres (6.6 ft) in bell
height and diameter; the tentacles and mouth parts usually extend beyond this bell dimension.
The smallest jellyfish are the peculiar creeping j
Jellyfish reproduce both sexually and asexually. Upon reaching adult size, jellyfish spawn daily given
enough food. In most species, spawning is controlled by light, so the entire population spawns at
about the same time of day, often at eith
Diagram of the anatomy of a scyphozoan jellyfish
The major surfaces and axes of a scyphozoan jellyfish
Most jellyfish do not have specialized digestive, osmoregulatory, central nervous, respiratory,
or circulatory systems. The manubrium is a stalk
Jellyfish lifespans typically range from a few hours (in the case of some very small hydromedusae)
to several months; there are some indications that deep sea species may live on the order of years.
Life span varies by species. Most large coastal
Jellyfish development occurs in multiple phases. Sperm fertilize eggs which develop into larval
planulae, become polyps, bud into ephyrae and then transform into adult medusae. In some species,
specimens may skip some phases.
The planula is a s
Jellyfish employ a loose network of nerves, located in the epidermis, which is called a "nerve net".
Although traditionally thought not to have a central nervous system, nerve net concentration
and ganglion-like structures could be con
Jellyfish have been proven to be the most energy efficient swimmers of all animals.  They move
through the water by radially expanding and contracting their bell-shaped bodies to push water
behind them. They pause between the contraction and
Sean Murphy, Tuesday, 3/13/13, Report #1
Tamburri, Mario., Halt, Magdelena., Robinson, Bruce. November, 2000. Chemically
regulated feeding by a midwater medusa. Limnology and Oceanography, Vol. 45, No.7.
We look at ctenophores and c