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Trachylina
Trachylinae (also Trachylina, Trachylinida, etc.) is a subclass of hydrozoans. It is placed at order rank in many older classifications, and limited to contain the Narcomedusae, Trachymedusae, the Actinulidae, then considered an independent order, and also the Limnomedusae which were traditionally placed in the paraphyletic "Hydroida". It is not entirely clear whether the Limnomedusae and the Trachymedusae as conventionally circumscribed are monophyletic The freshwater jelly ''Craspedacusta sowerbyi'' is a well-known member of the Limnomedusae and might thus belong here. Development Of the four orders: Narcomedusae, Trachymedusae, Actinulidae, and Limnomedusae, only Limnomedusae has any sort of polyp stage, and even then it is very tiny(less than 1mm) with no tentacles. This is uncommon for other jellyfish under the phylum cnidaria. These jellyfish also tend to have fewer cells during their embryonic and larvae A larva (; plural larvae ) is a distinct juvenile form many anim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trachylinae
Trachylinae (also Trachylina, Trachylinida, etc.) is a subclass of hydrozoans. It is placed at order rank in many older classifications, and limited to contain the Narcomedusae, Trachymedusae, the Actinulidae, then considered an independent order, and also the Limnomedusae which were traditionally placed in the paraphyletic "Hydroida". It is not entirely clear whether the Limnomedusae and the Trachymedusae as conventionally circumscribed are monophyletic The freshwater jelly ''Craspedacusta sowerbyi'' is a well-known member of the Limnomedusae and might thus belong here. Development Of the four orders: Narcomedusae, Trachymedusae, Actinulidae, and Limnomedusae, only Limnomedusae has any sort of polyp stage, and even then it is very tiny(less than 1mm) with no tentacles. This is uncommon for other jellyfish under the phylum cnidaria. These jellyfish also tend to have fewer cells during their embryonic and larvae A larva (; plural larvae ) is a distinct juvenile form many ani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrozoa
Hydrozoa (hydrozoans; ) are a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline water. The colonies of the colonial species can be large, and in some cases the specialized individual animals cannot survive outside the colony. A few genera within this class live in freshwater habitats. Hydrozoans are related to jellyfish and corals and belong to the phylum Cnidaria. Some examples of hydrozoans are the freshwater jelly (''Craspedacusta sowerbyi''), freshwater polyps ('' Hydra''), ''Obelia'', Portuguese man o' war (''Physalia physalis''), chondrophores (Porpitidae), "air fern" (''Sertularia argentea''), and pink-hearted hydroids (''Tubularia''). Anatomy Most hydrozoan species include both a polyp (zoology), polypoid and a medusa (biology), medusoid stage in their lifecycles, although a number of them have only one or the other. For example, ''Hydra'' has no medusoid stage, while ''Liriope tetraphylla, Lir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrozoans
Hydrozoa (hydrozoans; ) are a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline water. The colonies of the colonial species can be large, and in some cases the specialized individual animals cannot survive outside the colony. A few genera within this class live in freshwater habitats. Hydrozoans are related to jellyfish and corals and belong to the phylum Cnidaria. Some examples of hydrozoans are the freshwater jelly (''Craspedacusta sowerbyi''), freshwater polyps ('' Hydra''), ''Obelia'', Portuguese man o' war (''Physalia physalis''), chondrophores (Porpitidae), "air fern" (''Sertularia argentea''), and pink-hearted hydroids (''Tubularia''). Anatomy Most hydrozoan species include both a polypoid and a medusoid stage in their lifecycles, although a number of them have only one or the other. For example, ''Hydra'' has no medusoid stage, while '' Liriope'' lacks the polypoid stage. Polyps The hydroid fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Narcomedusae
Narcomedusae is an order of hydrozoans in the subclass Trachylinae. Members of this order do not normally have a polyp stage. The medusa has a dome-shaped bell with thin sides. The tentacles are attached above the lobed margin of the bell with usually a gastric pouch above each. There are no bulbs on the tentacles and no radial canals. Narcomedusans are mostly inhabitants of the open sea and deep waters. They can be found in the Mediterranean in large numbers. Feeding Behavior Narcomedusae use their tentacles to catch large, fast-moving prey. They do this by holding their tentacles perpendicular to the direction they are swimming to cover a larger area. If something is caught they bend the tentacle inwards and coil them at the tips to their mouths. References Gallery File:Aeginura grimaldii by Haeckel.png, ''Aeginura grimaldii'' by Ernst Haeckel Ernst Heinrich Philipp August Haeckel (; 16 February 1834 – 9 August 1919) was a German zoologist, naturalist, eugenicis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinulidae
Actinulida are an order of hydrozoans in the subclass Trachylinae Trachylinae (also Trachylina, Trachylinida, etc.) is a subclass of hydrozoans. It is placed at order rank in many older classifications, and limited to contain the Narcomedusae, Trachymedusae, the Actinulidae, then considered an independent orde .... Very small, medusoid Hydrozoa without polyp phase, living in the sand interstitial, solitary, bell entirely or very much reduced, epidermis ciliated, 1-2 whorls of tentacles, statocysts present or not, club shaped and derived of ecto- and entodermal tissue; cnidome may include stenoteles. References Cnidarian orders Trachylinae {{Hydrozoa-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinulida
Actinulida are an order of hydrozoans in the subclass Trachylinae Trachylinae (also Trachylina, Trachylinida, etc.) is a subclass of hydrozoans. It is placed at order rank in many older classifications, and limited to contain the Narcomedusae, Trachymedusae, the Actinulidae, then considered an independent orde .... Very small, medusoid Hydrozoa without polyp phase, living in the sand interstitial, solitary, bell entirely or very much reduced, epidermis ciliated, 1-2 whorls of tentacles, statocysts present or not, club shaped and derived of ecto- and entodermal tissue; cnidome may include stenoteles. References Cnidarian orders Trachylinae {{Hydrozoa-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limnomedusae
Limnomedusae is an order of hydrozoans. Taxonomy The taxon was erected by Danish marine biologist Paul Lassenius Kramp in 1938 to accommodate certain families of hydrozoans with biphasic life histories. It includes genera with medusae with ecto-endodermal statocysts and with gonads alongside their radial canals, and also genera which have polyps that are not covered by a theca. Molecular analysis performed by Collins in 2006 has since shown that the Limnomedusae are not monophylic. The family Armorhydridae, which contains a single genus and a single species, '' Armorhydra janowiczi'', is found living in coarse sediment, has hollow tentacles and has no radial canals. It seems to share few morphological features with the other families and probably belongs elsewhere. The inclusion of Microhydrulidae is also dubious. The medusa stage is not known and the tiny polyp has no tentacles nor mouth. Systematic list The World Register of Marine Species currently lists the following fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trachymedusae
Trachymedusae belong to the phylum Cnidaria and the class Hydrozoa, among the 30 genera are 5 families containing around 50 species in all, the family Rhopalonematidae has the greatest diversity. Description Trachymedusae are identifiable by their umbrella edge which lacks any lobes. The tentacles at the edge of the umbrellas are solid or solid and hollow, there is a thickened tissue ring that has a large number of nematocysts, the radial canals number from 4 to 6 to 8 and more than 8, though 8 is the most common amount found. The sensory clubs can be open or closed with the endodermal axis. The gonads are generally located at the radial canal or where the radial canal and the manubrium connect. The cnidome may have stenoteles. Trachymedusae reproduce sexually during the medusae stage lacking a polyp stage. Primarily found in the deep ocean, where they are recorded at depths of seventy to two thousand metres. Interactions with humans Interactions with humans are few as this spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyp (zoology)
A polyp in zoology is one of two forms found in the phylum Cnidaria, the other being the medusa. Polyps are roughly cylindrical in shape and elongated at the axis of the vase-shaped body. In solitary polyps, the aboral (opposite to oral) end is attached to the substrate by means of a disc-like holdfast called a pedal disc, while in colonies of polyps it is connected to other polyps, either directly or indirectly. The oral end contains the mouth, and is surrounded by a circlet of tentacles. Classes In the class Anthozoa, comprising the sea anemones and corals, the individual is always a polyp; in the class Hydrozoa, however, the individual may be either a polyp or a medusa, with most species undergoing a life cycle with both a polyp stage and a medusa stage. In class Scyphozoa, the medusa stage is dominant, and the polyp stage may or may not be present, depending on the family. In those scyphozoans that have the larval planula metamorphose into a polyp, the polyp, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Larvae
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The larva's appearance is generally very different from the adult form (''e.g.'' caterpillars and butterflies) including different unique structures and organs that do not occur in the adult form. Their diet may also be considerably different. Larvae are frequently adapted to different environments than adults. For example, some larvae such as tadpoles live almost exclusively in aquatic environments, but can live outside water as adult frogs. By living in a distinct environment, larvae may be given shelter from predators and reduce competition for resources with the adult population. Animals in the larval stage will consume food to fuel their transition into the adult form. In some organisms like polychaetes and barnacles, adults are immobil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embryo
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm cell. The resulting fusion of these two cells produces a single-celled zygote that undergoes many cell divisions that produce cells known as blastomeres. The blastomeres are arranged as a solid ball that when reaching a certain size, called a morula, takes in fluid to create a cavity called a blastocoel. The structure is then termed a blastula, or a blastocyst in mammals. The mammalian blastocyst hatches before implantating into the endometrial lining of the womb. Once implanted the embryo will continue its development through the next stages of gastrulation, neurulation, and organogenesis. Gastrulation is the formation of the three germ layers that will form all of the different parts of the body. Neurulation forms the nervous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crossota
''Crossota'' is a genus of hydrozoans of the family Rhopalonematidae. The genus comprises five species. Unlike most hydromedusae, these do not have a sessile stage. Rather, they spend their entire lives in the water column as plankton. The genus ''Crossota'' is widespread throughout the oceans. Species *''Crossota alba'' *''Crossota brunnea'' *''Crossota millsae'' *''Crossota norvegica'' *''Crossota rufobrunnea ''Crossota rufobrunnea'' is a species of hydrozoan. References Animals described in 2016 Rhopalonematidae {{hydrozoa-stub ...'' References World Register of Marine Species Rhopalonematidae Hydrozoan genera Bioluminescent cnidarians {{hydrozoa-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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