| Mertensiidae | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Ctenophora |
| Class: | Tentaculata |
| Order: | Cydippida |
| Family: | Mertensiidae |
Mertensiidae is a family of ctenophores belonging to the order Cydippida. [1]
Genera: [1]
Cydippida is an order of comb jellies. They are distinguished from other comb jellies by their spherical or oval bodies, and the fact their tentacles are branched, and can be retracted into pouches on either side of the pharynx. The order is not monophyletic, that is, more than one common ancestor is believed to exist.
Mertensia ovum, also known as the Arctic comb jelly or sea nut, is a cydippid comb jelly or ctenophore first described as Beroe ovum by Johan Christian Fabricius in 1780. It is the only species in the genus Mertensia. Unusually among ctenophores, which normally prefer warmer waters, it is found in the Arctic and adjacent polar seas, mostly in surface waters down to 50 metres (160 ft).
Callianira hexagona is a species of ctenophore of the family Mertensiidae. The scientific name of this species was first published in 1789 by Bruguière.
Euplokamis is a genus of ctenophores, or comb jellies, belonging to the monotypic family Euplokamididae. Despite living for hundreds of millions of years in marine environments, there is minimal research regarding Euplokamis, primarily due to their body structure. Research on the evolution of the basic body structures of diploblastic metazoans revealed that there are four major phyla, including the Ctenophores. Although the morphology of Euplokamis often resembles the medusa stage of Cnidarians, their eight rows of combs are one distinguishing feature that led to the official classification of Ctenophores. After being originally described by Chun (1879), the family Euplokamididae was expanded by Mills (1987) due to the discovery of a new species, Euplokamis dunlapae. Further research indicated that Euplokamis should be identified from Mertensiidae due to the rows of combs and some compression. They may also be distinguished from the genus Pleurobrachia due to their more elongated shape. Additionally, various adaptations of Euplokamis have been observed such as the use of tentacles for movement/feeding, a complex nervous system, and bioluminescent capabilities. Other characteristics including a defined mesoderm, lack of stinging cells, developmental differences, and symmetry supported the reclassification of these organisms.
Callianira is a genus of ctenophores belonging to the family Mertensiidae.
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