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Leptothecata
Leptothecata, or thecate hydroids, are an order of hydrozoans in the phylum Cnidaria. Their closest living relatives are the athecate hydroids, which are similar enough to have always been considered closely related, and the very apomorphic Siphonophorae, which were placed outside the "Hydroida". Given that there are no firm rules for synonymy for high-ranked taxa, alternative names like Leptomedusa, Thecaphora or Thecata, with or without the ending emended to "-ae", are also often used for Leptothecata. In the sessile stage, Leptothecata are surrounded by a chitinous outer layer as their exoskeleton, including the gonophores, their reproductive organ. Leptothecata exhibit radial symmetry, and their gonads can be found in the radial canals of the medusa stage. Their habits range from benthic to planktonic. The polyps and colonial forms are benthic, whilst the medusae are planktonic. Leptothecata exhibit extensive, complex variation. Thecata colonies also have extensive specia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Fern
The air fern (''Sertularia argentea'') is a dead and dried colony of hydrozoans, a species of marine animal in the family Sertulariidae related to corals and jellyfish. Air ferns are typically dyed green and sold as a curiosity, as a decorative "indoor plant"; the same skeletons of former colonies of hydroids are sold in their natural dried state as the sea fir and Neptune plant as underwater decorations for aquariums. Description Despite a superficial resemblance to plants, air ferns are actually animal skeletons or Exoskeleton, shells of marine (ocean), marine hydroid (zoology), hydroids of the Class (biology), class Hydrozoa, phylum Cnidaria. The dried colonies are often dyed green, but the coloring will dissolve when soaked in water. Undyed ferns are sometimes labeled as "Neptune plants". The fernlike branches of ''S. argentea'' are composed of many small, chitinous chambers where individual animals once lived. When the colony was alive, a polyp (zoology), polyp with nume ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
