Such a life cycle characterizes the order Semaeostomeae, which contains some 50 species of mainly coastal-water jellyfish, several of which have very wide geographic ranges. After the planula larva leaves its parent, it lives for a time in the plankton and eventually attaches to a rock or other solid surface, where it grows into a new scyphistoma.

In many species, normal fusion of egg and sperm results in an embryo that is brooded in the gut of the adult until it becomes a ciliated planula larva, but in some this development takes place in the sea.

The adults are either male or female, but in some species they change their sex as they age. A sessile polyp ( scyphistoma) stage asexually buds off young medusae from its upper end, with each such ephyra growing into an adult. The life cycle of free-swimming scyphozoan jellyfish typically consists of three stages. Explore your knowledge of kangaroos and koalas in this quiz. In jellyfish the transparent mesoglea layer is quite thick.Īustralia abounds with native animals big and small. Like all cnidarians, their bodies are made up of two cellular layers, the ectoderm and the endoderm, between which lies the gelatinous mesoglea. Some, however, simply suspension feed, extracting minute animals and algae (phytoplankton) from the water. Most feed on copepods, fish larvae, and other small animals that they catch in their tentacles, which have stinging cells (nematocysts). Scyphozoan medusae consist of almost 99 percent water as a result of the composition of the jelly that forms the bulk in nearly all species. The bodies of most range in size from about 2 to 40 cm (1 to 16 inches) in diameter some species are considerably larger, however, with diameters of up to 2 metres (6.6 feet). Most live for only a few weeks, but some are known to survive a year or longer.

See all videos for this articleįree-swimming scyphozoan jellyfish occur in all oceans and include the familiar disk-shaped animals that are often found drifting along the shoreline. Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions.Ī jellyfish contracting its body.This Time in History In these videos, find out what happened this month (or any month!) in history.#WTFact Videos In #WTFact Britannica shares some of the most bizarre facts we can find.Demystified Videos In Demystified, Britannica has all the answers to your burning questions.Britannica Classics Check out these retro videos from Encyclopedia Britannica’s archives.

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