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Hydrozoan Genera
Hydrozoa (hydrozoans; from Ancient Greek ('; "water") and ('; "animals")) is 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, which also 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), and pink-hearted hydroids ('' Tubularia''). Anatomy Most hydrozoan species include both a polypoid and a medusoid stage in their life cycles, although a number of them have only one or the other. For example, ''Hydra'' has no medusoid stage, while '' Liriope'' lacks the polypoid st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siphonophorae
Siphonophorae (from Ancient Greek σίφων (siphōn), meaning "tube" and -φόρος (-phóros), meaning "bearing") is an order within Hydrozoa, 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. Siphonophores are highly polymorphic and complex organisms. Although they may appear to be individual organisms, 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 biolumines ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saline Water
Saline water (more commonly known as salt water) is water that contains a high concentration of dissolved salts (mainly sodium chloride). On the United States Geological Survey (USGS) salinity scale, saline water is saltier than brackish water, but less salty than brine. The salt concentration is usually expressed in parts per thousand (permille, ‰) and parts per million (ppm). The USGS salinity scale defines three levels of saline water. The salt concentration in slightly saline water is 1,000 to 3,000 ppm (0.1–0.3%); in moderately saline water is 3,000 to 10,000 ppm (0.3–1%); and in highly saline water is 10,000 to 35,000 ppm (1–3.5%). Seawater has a salinity of roughly 35,000 ppm, equivalent to 35 grams of salt per one liter (or kilogram) of water. The saturation level is only nominally dependent on the temperature of the water. At one liter of water can dissolve about 357 grams of salt, a concentration of 26.3 percent by weight (% w/w). At (the boiling temper ... [...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, spawning the common name as either the pink-mouthed or pink-hearted hydroid. Description The average height of an individual colony is and the diameter of the polyp and tentacles is . ''Tubularia'' occurs either individually or in colonies, both being dioecious and possessing large, brilliantly coloured, flowerlike hydrants. Medusae remain attached to the hypostome in clusters, never being dispersed. Life cycle During the summer, sperm are released into the water and attracted to female reproductive structures by means of a chemical substance. Internal fertilization occurs in the female medusoids. The fertilized eggs develop into actinula. These larvae develop directly into a new polyp. Although the medusa are attached to the polyp, the life cycle resembles that of typical Cnidarian with the polyp reproducing asexually and the medusa producing egg and sperm. Similar ... [...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, some find the term ''chondrophore'' still useful as a synonym for members of the family Porpitidae – ''porpitids'' – when discussing the two genera contained in '' Porpita'' and ''Velella'', to avoid confusion with the near-identical genus name '' Porpita''. They all live at the surface of the open ocean, and are colonies of carnivorous, free-floating hydroids. 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 colony's role in the plankton community is similar to that of pelagic jellyfish. 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Portuguese Man O' War
The Portuguese war (''Physalia physalis''), also known as the man-of-war or bluebottle, is a marine hydrozoan found in the Atlantic Ocean and the Indian Ocean. It is the only species in the genus ''Physalia'', which in turn is the only genus in the family Physaliidae. The name ''man o’ war'' comes from the man-of-war, a sailing warship, and the animal's resemblance to the Portuguese version (the caravel) at full sail. The man o' war are part of the neuston, organisms that live on the surface of the water. A gas-filled bladder provides buoyancy that lets the animal stay afloat on the surface of the water while tentacles which can be up to165 ft (9 to 50 m) long hang below the surface, containing venomous Cnidocyte, cnidocytes that help capture prey. The cnidocytes can deliver a sting powerful enough to kill fish, and even, in some cases, humans. A sail on the bladder, which may be left or right-handed, propels it about the sea, often in groups. Although it superficially resembl ... [...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. bidentata'', ''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 usual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydra (genus)
''Hydra'' ( ) is a genus of small freshwater hydrozoans of the phylum Cnidaria. They are solitary, carnivorous jellyfish-like animals, native to the temperate and tropical regions. The genus was named by Linnaeus in 1758 after the Hydra, which was the many-headed beast of myth defeated by Heracles, as when the animal has a part severed, it will regenerate much like the mythical hydra's heads. Biologists are especially interested in ''Hydra'' because of their regenerative ability; they do not appear to die of old age, or to age at all. Habitat Hydras are often found in freshwater bodies, but some hydras are found in open water. They live attached to submerged rocks using a sticky secretion from their base. Morphology ''Hydra'' has a tubular, radially symmetric body up to long when extended, secured by a simple adhesive foot known as the basal disc. Gland cells in the basal disc secrete a sticky fluid that accounts for its adhesive properties. At the free end of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Craspedacusta Sowerbyi
''Craspedacusta sowerbii'' or peach blossom jellyfish is a species of freshwater hydrozoan jellyfish, or hydromedusa cnidarian. Hydromedusan jellyfish differ from scyphozoan jellyfish because they have a muscular, shelf-like structure called a velum on the ventral surface, attached to the bell margin. Originally from the Yangtze basin in China, ''C. sowerbii'' is an introduced species now found throughout the world in bodies of fresh water. Form ''C. sowerbii'' medusae are about 20–25 mm (approximately 1 in.) in diameter, somewhat flatter than a hemisphere, and very delicate, when fully grown. They have a whorl of up to 400 tentacles tightly packed around the bell margin. Hanging down from the center of the inside of the bell is a large stomach structure called a manubrium, with a mouth-opening with four frilly lips. Circulation of nutrients is facilitated by four radial canals which originate at the edges of the stomach (manubrium), and which are also connected to a rin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cnidaria
Cnidaria ( ) is a phylum under kingdom Animalia containing over 11,000 species of aquatic invertebrates found both in fresh water, freshwater and marine environments (predominantly the latter), including jellyfish, hydroid (zoology), hydroids, sea anemones, corals and some of the smallest marine parasites. Their distinguishing features are an uncentralized nervous system distributed throughout a gelatinous body and the presence of cnidocytes or cnidoblasts, specialized cells with ejectable flagella used mainly for envenomation and capturing prey. Their bodies consist of mesoglea, a non-living, jelly-like substance, sandwiched between two layers of epithelium that are mostly one cell (biology), cell thick. Cnidarians are also some of the few animals that can reproduce both sexually and asexually. Cnidarians mostly have two basic body forms: swimming medusa (biology), medusae and sessility (motility), sessile polyp (zoology), polyps, both of which are radially symmetrical with mou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylum (biology)
In biology, a phylum (; : phyla) is a level of classification, or taxonomic rank, that is below kingdom and above class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclature for algae, fungi, and plants accepts the terms as equivalent. Depending on definitions, the animal kingdom Animalia contains about 31 phyla, the plant kingdom Plantae contains about 14 phyla, and the fungus kingdom Fungi contains about eight phyla. Current research in phylogenetics is uncovering the relationships among phyla within larger clades like Ecdysozoa and Embryophyta. General description The term phylum was coined in 1866 by Ernst Haeckel from the Greek (, "race, stock"), related to (, "tribe, clan"). Haeckel noted that species constantly evolved into new species that seemed to retain few consistent features among themselves and therefore few features that distinguished them as a group ("a self-contained unity"): "perhap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coral
Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral reef, reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton. A coral "group" is a colony of very many cloning, genetically identical polyps. Each polyp is a sac-like animal typically only a few millimeters in diameter and a few centimeters in height. A set of tentacles surround a central mouth opening. Each polyp excretes an exoskeleton near the base. Over many generations, the colony thus creates a skeleton characteristic of the species which can measure up to several meters in size. Individual colonies grow by asexual reproduction of polyps. Corals also breed sexually by spawning: polyps of the same species release gametes simultaneously overnight, often around a full moon. Fertilized eggs form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jellyfish
Jellyfish, also known as sea jellies or simply jellies, are the #Life cycle, medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals, although a few are anchored to the seabed by stalks rather than being motile. They are made of an umbrella-shaped main body made of mesoglea, known as the ''bell'', and a collection of trailing tentacles on the underside. Via pulsating contractions, the bell can provide propulsion for animal locomotion, locomotion through open water. The tentacles are armed with cnidocyte, stinging cells and may be used to capture prey or to defend against predators. Jellyfish have a complex biological life cycle, life cycle, and the medusa is normally the sexual phase, which produces planula larvae. These then disperse widely and enter a sedentary #Life cycle, polyp phase which may include asexual budding before reaching sexual maturity. Jellyfish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
