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Siphonophorae (from Greek siphōn 'tube' + pherein 'to bear' [2]) is an order within Hydrozoa, which is a class of marine organisms within the phylum Cnidaria.According to the World Register of Marine Species, the order contains 175 species described thus far.
Pacific sea nettles, Chrysaora fuscescens. Cnidaria (/ n ɪ ˈ d ɛər i ə, n aɪ-/ nih-DAIR-ee-ə, NY-) [4] is a phylum under kingdom Animalia containing over 11,000 species [5] of aquatic invertebrates found both in fresh water and marine environments (predominantly the latter), including jellyfish, hydroids, sea anemones, corals and some of the smallest marine parasites.
The developmental stages of scyphozoan jellyfish's life cycle: 1–3 Larva searches for site 4–8 Polyp grows 9–11 Polyp strobilates 12–14 Medusa grows. Most species appear to be gonochorists, with separate male and female individuals. The gonads are located in the stomach lining, and the mature gametes are expelled through the mouth ...
Like many Hydrozoa, Velella velella has a bipartite life cycle, with a form of alternation of generations. The deep blue, by-the-wind sailors that are recognized by many beach-goers are the polyp phase of the life cycle. Each "individual" with its sail is really a hydroid colony, with many polyps that feed on ocean plankton.
The cnidae, the explosive cells characteristic of the Cnidaria and used in prey capture and defence, are of a single type, there being nematocysts but no spirocysts or ptychocysts. [4] In contrast, the anthozoan life cycle involves a planula larva which settles and becomes a sessile polyp, which is the adult or sexual phase.
Polypodium was long considered a unique intracellular parasite among cnidarians. [6] [7] Its hosts include 14 species of Acipenser, 2 species of Huso, Polyodon spathula [6] and Scaphirhynchus platorynchus. [2] Polypodium hydriforme is an endocellular parasite with an unusual life cycle, a peculiar morphology, and high rates of DNA evolution.
Animals: Amphibians · Arachnids · Birds · Cnidaria · Crustaceans · Echinoderms · Fish · Insects · Mammals · Molluscs · Reptiles · Others Sarcophyton glaucum , by Poco a poco Parazoanthus axinellae , by Poco a poco
Praya dubia zooids arrange themselves in a long stalk—usually whitish and transparent (though other colours have been seen [5])—known as a physonect colony. [6] The larger end features a transparent, dome-like float known as a pneumatophore, [7] filled with gas which provides buoyancy, allowing the organism to remain at its preferred ocean depth.