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The Scyphozoa are an exclusively marine class of the phylum Cnidaria, [2] referred to as the true jellyfish (or "true jellies"). The class name Scyphozoa comes from the Greek word skyphos (σκύφος), denoting a kind of drinking cup and alluding to the cup shape of the organism. [3] Scyphozoans have existed from the earliest Cambrian to the ...
Protein and medusae analysis from Michael N. Dawson of the University of New South Wales confirm that Cyanea annaskala is a valid species, morphologically distinct based on differences in bell mass, number of nematocyst clusters, pits in coronal muscle folds, and other morphological characteristics. Some of the other morphological ...
Scyphozoa is the group commonly known as "true jellyfish" and occur in tropical, temperate and polar seas worldwide. Scyphozoans generally have planula larvae that develop into sessile polyps. These reproduce asexually, producing similar polyps by budding, and then either transform into medusae, or repeatedly bud medusae from their upper ...
Velella is a monospecific genus of hydrozoa in the Porpitidae family. Its only known species is Velella velella, [2] a cosmopolitan (widely distributed) free-floating hydrozoan that lives on the surface of the open ocean.
These muscle fibres belong to the same two systems, allowing the whole body to retract or protrude outwards. [ 1 ] We can distinguish therefore in the body of a polyp the column, circular or oval in section, forming the trunk, resting on a base or foot and surmounted by the crown of tentacles, which enclose an area termed the peristome , in the ...
The mesoglea is mostly acellular, [2] but in both cnidaria [3] and ctenophora [4] the mesoglea contains muscle bundles and nerve fibres. Other nerve and muscle cells lie just under the epithelial layers. [2] The mesoglea also contains wandering amoebocytes that play a role in phagocytosing debris and bacteria. These cells also fight infections ...
Jellyfish have two main types of muscle: epitheliomuscular cells and striated muscle cells. Researchers found that gene families that are closely associated with striated muscle were expressed in the bell portion of the jellyfish, providing evidence that striated muscle plays a significant role in jellyfish motility. [4]
On the oral side of the rhopalium near the lithocyst is a mass of sensory cells called the "pigment-cup ocellus", while on the aboral side, there is a “pigment-spot ocellus” just proximal to the lithocyst, formed by a patch of pigment cells. [1]