Scyphozoa

Scyphozoa, commonly known as true jellyfish, are a class of gelatinous, free-swimming marine animals within the phylum Cnidaria. They are characterized by their bell-shaped bodies, with tentacles that extend from the edge of the bell. Scyphozoans have a complex life cycle that includes both polyp and medusa stages. The medusa stage, the more familiar jellyfish form, is typically the dominant phase. They are found in all oceans, from shallow coastal waters to the deep sea.

Purple Jellyfish, Rasta Jelly, Pellagic Purple Jellyfish – Thysanostoma loriferum

Jellyfish – Thysanostoma thysanura

Amakusa Jellyfish – Sanderia malayensis

Rhopilema esculentum

Football Jellyfish, Yellow Mediterranean Cabbage Bleb, – Rhizostoma pulmo

Giant Nomad Jellyfish – Rhopilema nomadica

Rhopilema asamushi

Fried Egg Jellyfish,egg-yolk Jellyfish – Phacellophora camtschatica

Crowned Jellyfish – Cephea cephea

Upside-down Sea Jelly – Cassiopea andromeda

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Characteristics

Scyphozoa exhibit several distinct characteristics that differentiate them from other cnidarians:

  • Bell-shaped body: The most recognizable feature of Scyphozoans is their bell-shaped body, which is comprised of a gelatinous substance called mesoglea.
  • Tentacles: Tentacles extend from the edge of the bell and are armed with stinging cells called nematocysts. These cells are used to capture prey and defend against predators.
  • Mouth: The mouth is located on the underside of the bell and serves as both the entrance for food and the exit for waste.
  • Life cycle: Scyphozoans have a complex life cycle that includes both a polyp stage and a medusa stage. The polyp stage is typically sessile and resembles a miniature anemone. The medusa stage is the free-swimming jellyfish form.
  • Nervous system: Scyphozoans possess a simple nervous system, with a network of nerves that allows them to respond to stimuli in their environment.

Environments

Scyphozoans are found in all oceans worldwide. They prefer waters with moderate to high salinity. They can be found in a variety of habitats, including:

  • Coastal waters: Many Scyphozoan species are found in shallow coastal waters, often near the shore.
  • Open ocean: Some species are pelagic and can be found in the open ocean, far from land.
  • Deep sea: A few Scyphozoans have adapted to life in the deep sea, where they may lack pigmentation and possess bioluminescent properties.

References

For further information on Scyphozoa, please consult the following resources: