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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] |
Hydroidolina
Hydroidolina is a subclass of Hydrozoa and makes up 90% of the class. Controversy surrounds who the sister groups of Hydroidolina are, but research has shown that three orders remain consistent as direct relatives: Siphonophorae, Anthoathecata, and Leptothecata. Description and background The phylum Cnidaria contains two clades: Anthozoa and Medusozoa. There are around 3800 species within the clade Medusozoa and it consists of Cubozoans, Scyphozoans, and Hydrozoans. Hydroidolina are small predatory animals, ranging in 8-30 millimeters in size, exhibiting radial symmetry and are diploblastic (developed from two embryonic layers: ectoderm and endoderm). The classification below is based on the World Register of Marine Species: Subclass Hydroidolina * Order Anthoathecata * Order Leptothecata * Order Siphonophorae Distribution Hydroidolina are commonly found in a variety of marine environments across the world such as deepwater caves or brackish and fresh shallow waters, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jellyfish
Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile. The bell can pulsate to provide propulsion for highly efficient animal locomotion, locomotion. The tentacles are armed with Cnidocyte, stinging cells and may be used to capture prey and defend against predators. Jellyfish have a complex Biological life cycle, life cycle; the medusa is normally the sexual phase, which produces planula larvae that disperse widely and enter a sedentary polyp (zoology), polyp phase before reaching sexual maturity. Jellyfish are found all over the world, from surface waters to the deep sea. Scyphozoans (the "true jellyfish") are exclusively marine habitats, marine, but some hydrozoans with a simila ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medusa (biology)
Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile. The bell can pulsate to provide propulsion for highly efficient locomotion. The tentacles are armed with stinging cells and may be used to capture prey and defend against predators. Jellyfish have a complex life cycle; the medusa is normally the sexual phase, which produces planula larvae that disperse widely and enter a sedentary polyp phase before reaching sexual maturity. Jellyfish are found all over the world, from surface waters to the deep sea. Scyphozoans (the "true jellyfish") are exclusively marine, but some hydrozoans with a similar appearance live in freshwater. Large, often colorful, jellyfish are common in coa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cnidaria
Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing feature is cnidocytes, specialized cells that they use mainly for capturing prey. Their bodies consist of mesoglea, a non-living jelly-like substance, sandwiched between two layers of epithelium that are mostly one cell thick. Cnidarians mostly have two basic body forms: swimming medusae and sessile polyps, both of which are radially symmetrical with mouths surrounded by tentacles that bear cnidocytes. Both forms have a single orifice and body cavity that are used for digestion and respiration. Many cnidarian species produce colonies that are single organisms composed of medusa-like or polyp-like zooids, or both (hence they are trimorphic). Cnidarians' activities are coordinated by a decentralized nerve net and simple receptors. Several free-swimming species of Cubozoa and Scyphozo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siphonophorae
Siphonophorae (from Greek ''siphōn'' 'tube' + ''pherein'' 'to bear') 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 thus far. Although a siphonophore may appear to be an individual organism, each specimen is in fact a colonial organism composed of medusoid and polypoid zooids that are morphologically and functionally specialized. Zooids are multicellular units that develop from a single fertilized egg and combine to create functional colonies able to reproduce, digest, float, maintain body positioning, and use jet propulsion to move. Most colonies are long, thin, transparent floaters living in the pelagic zone. Like other hydrozoans, some siphonophores emit light to attract and attack prey. While many sea animals produce blue and green bioluminescence, a siphonophore in the genus ''Erenna'' was only the second life form found to produce a red li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liriope Tetraphylla
''Liriope'' is a genus of hydrozoan in the family Geryoniidae. It contains only one species, ''Liriope tetraphylla''. Description ''Liriope tetraphylla'' has marginal tentacles, a manubrium, and gonads that are all green or rose-red in colour. It has a nearly hemispherical umbrella which is normally 10 to 30 mm wide. The exumbrella has four interradial and four perradial nematocyst tracks that are short in length. It has a well-developed velum. Normally, there are four radial canals that are straight. The ring canal is broad, and each quadrant has 1 to 3 (and possibly more) centriipedal canals that are short and blind. A marginal nematocyst ring is present. It has thick jelly, particularly in the region towards the apex. The manubrium of ''Liriope tetraphylla'' are extend from a long, gastric pendicule. These manubrium are normally 1 to 3 times the height of the umbrella. There are four lips on the mouth that are either simple or slightly crenulated. The subumbrellar part ... [...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] |
Tubularia
''Tubularia'' is a genus of hydroids resembling furry pink tufts or balls at the end of long strings, owing to the common names "pink-mouthed" or "pink-hearted" hydroids. Description The average height of an individual colony is 40–60 mm and the diameter of the polyp and tentacles is 10mm. ''Tubularia indivisa'' and ''Ectopleura larynx'' may be difficult to distinguish and the two often grow together. In ''E. larynx'' the stems branch while in ''T. indivisa'' they are unbranched. Tubularia occurs either solitary or in colonies, both being dioecious; possessing large, brilliantly coloured, flowerlike hydrants. Medusae Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella- ... remain attached to the hypostome in clusters, never being dispersed. These animals represent structures o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Fern
The air fern (''Sertularia argentea'') is a species of marine animal in the family Sertulariidae. It is also known as the sea fir and Neptune plant. These so-called "ferns" are dead and dried colonies of hydrozoans, colonies of marine hydroids, class Hydrozoa, phylum Cnidaria. Hydroids are related to corals and jellyfish. These dried hydroid colonies are commonly sold as a curiosity, as a decorative "indoor plant", or as underwater decorations for aquaria in stores. They are sometimes labeled as "Neptune plants". Despite a superficial resemblance to plants, they are actually animal skeletons or shells. The dried colonies are often dyed green, but, when soaked in water, the coloring will dissolve. 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 with numerous tentacles occupied each of the chambers, called hydrotheca. Sometimes dried bryozoa are sold as "air f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chondrophore
The chondrophores or porpitids are a small group of hydrozoans in the family Porpitidae. Though it derives from an outdated name for this lineage (see below), some still find the term "chondrophore" useful as a synonym to "porpitid" in discussions of the two genera contained therein. They all live at the surface of the open ocean, and are colonies of carnivorous, free-floating hydroids whose role in the plankton community is similar to that of pelagic jellyfish. The chondrophores look like a single organism but are actually colonial animals, made up of orderly cooperatives of polyps living under specialized sail-structures. The most familiar members of the family Porpitidae are the blue button (''Porpita porpita'') and the by-the-wind sailor (''Velella velella''). Description The tiny individual animals are specialized to perform specific tasks; some form the central gas-filled disc (which is a golden brown colour and hardened by chitinous material) essential to keeping the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portuguese Man O' War
The Portuguese man o' war (''Physalia physalis''), also known as the man-of-war, is a marine hydrozoan found in the Atlantic Ocean and the Indian Ocean. It is considered to be the same species as the Pacific man o' war or blue bottle, which is found mainly in the Pacific Ocean. The Portuguese man o' war is the only species in the genus ''Physalia'', which in turn is the only genus in the family Physaliidae. The Portuguese man o' war is a conspicuous member of the neuston, the community of organisms that live at the ocean surface. It has numerous venomous microscopic nematocysts which deliver a painful sting powerful enough to kill fish, and has been known to occasionally kill humans. Although it superficially resembles a jellyfish, the Portuguese man o' war is in fact a siphonophore. Like all siphonophores, it is a colonial organism, made up of many smaller units called zooids. All zooids in a colony are genetically identical, but fulfill specialized functions such as feeding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Obelia
''Obelia'' is a genus of hydrozoans, a class of mainly marine and some freshwater animal species that have both polyp and medusa stages in their life cycle. Hydrozoa belongs to the phylum Cnidaria, which are aquatic (mainly marine) organisms that are relatively simple in structure with a diameter around 1mm. There are currently 120 known species, with more to be discovered. These species are grouped into three broad categories: ''O. bidentada'', ''O. dichotoma'', and ''O. geniculata''. ''O. longissima'' was later accepted as a legitimate species, but taxonomy regarding the entire genus is debated over. ''Obelia'' is also called sea fur. ''Obelia'' has a worldwide distribution except the high-Arctic and Antarctic seas. and a stage of ''Obelia'' species are common in coastal and offshore plankton around the world.Cornelius, P.F.S., 1995b. North-West European thecate hydroids and their Medusae. Part 2. Synopses of the British Fauna (New Series), No 50. ''Obelia'' are usually fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
