Athecate hydroids
| Athecate hydroids | |
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| Anatomical details of Pandeidae (Filifera). Lower left, top right: Neoturris pileata. Lower right: Stomotoca pterophylla. From Kunstformen der Natur by Ernst Haeckel (1904) |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Class: | Hydrozoa |
| Subclass: | Leptolinae |
| Order: |
Anthomedusae Haeckel, 1879 |
| Suborders | |
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Aplanulata |
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| Synonyms | |
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Aplanulata
Capitata
Filifera
and see text
Anthomedusae or Anthomedusa, the athecate hydroids, are an order of the Hydrozoa, a class of marine invertebrates belonging to the phylum Cnidaria. A profusion of alternate scientific names exists for this long-known, heavily discussed, and spectacular group. It has also been called Gymnoblastea and (with or without an emended ending -ae) Anthoathecata, Athecata, Hydromedusa, and Stylasterina. There are about 1,200 species worldwide.
These hydrozoans always have a polyp stage. Their hydranths grow either solitary or in colonies. There is no firm perisarc around the polyp body. The medusae, or jellyfish, are solitary animals, with tentacles arising from the bell margin, lacking but possessing radial canals. Their gonads are on the manubrium ("handle").
Except in Eudendriidae and Laingiidae, prey can be captured by discharging harpoon-like structures (desmonemes) from chambers (cnidae) in specialized cells () on the tentacles. In hydrozoans, these are nearly always adhesive and entrapping, rather than puncturing and poisoned as in other jellys.
Their close relationship to the Leptomedusae has been long known, but it was formerly believed that these two were also close to the Limnomedusae. However, their closest relatives are the highly advanced Siphonophorae, whereas the Limnomedusae are a rather primitive group, not very closely related to these three Leptolinae, and might belong to the Trachylinae subclass.
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Wikipedia