| Halecium halecinum | |
|---|---|
 | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Class: | Hydrozoa |
| Order: | Leptothecata |
| Family: | Haleciidae |
| Genus: | Halecium |
| Species: | H. halecinum |
| Binomial name | |
| Halecium halecinum | |
| Synonyms [1] | |
| |
Halecium halecinum, commonly known as the herring-bone hydroid, [2] is a species of hydrozoan in the family Haleciidae. It is native to the eastern Atlantic Ocean, the western Atlantic Ocean and the eastern Pacific Ocean.
This hydroid grows to a maximum height of 25 cm (10 in) but a more typical height is 10 cm (4 in). The colony grows in a single plane with stiff erect stems growing from a fibrous base. The growth is pinnate, with alternate secondary branches which are parallel to one another and join the main stem at an angle of about 50°, giving a herring-bone appearance. These in turn have stubby tertiary branches which bear the hydrothecae (feeding polyps); these grow on alternate sides of the stem, forming short, equal-length segments, separated by transverse nodes. The polyps are large and goblet-shaped, with down-turned rims. The reproductive gonothecae are borne on the upper surfaces of the branches, the male structures being ovoid and club-shaped, while the female ones are oblong, with tapering bases and broad flat upper surfaces with apertures in the corners. [2] [3] [4] [5]
This hydroid is known from the eastern Atlantic Ocean, the western Atlantic Ocean and the eastern Pacific Ocean. Its range extends from Spitsbergen, through the Mediterranean Sea and the coasts of Western Europe and West Africa to South Africa. It is also present in western Iceland and eastern Greenland, and southwards along the eastern coasts of North America to the Caribbean Sea and Colombia. In the eastern Pacific Ocean its range extends from Alaska to California and it is also present in the Mollucas, Japan and the Sea of Okhotsk. [5] It grows on hard surfaces such as shells and stones in the shallow sub-littoral zone and in deeper water. [6]
Research has shown that there are two types of hydrothecae with different behaviours. [7] The second type has a longer, extensible column and fewer, shorter, thicker tentacles armed with larger stinging cells. It can twist and coil during extension, and contract by bulging and folding while still remaining extended; both types of polyp can catch and ingest planktonic particles, but the extensible one is able to writhe around and explore a greater volume of water. [7] It is probably used in defence and may also have an excretory or sensory function. Such polyp dimorphism has been reported in three other species of hydroid. [7]
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 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.
Velella is a monospecific genus of hydrozoa in the Porpitidae family. Its only known species is Velella velella, a cosmopolitan free-floating hydrozoan that lives on the surface of the open ocean. It is commonly known by the names sea raft, by-the-wind sailor, purple sail, little sail, or simply Velella.
Turritopsis dohrnii, also known as the immortal jellyfish, is a species of small, biologically immortal jellyfish found worldwide in temperate to tropic waters. It is one of the few known cases of animals capable of reverting completely to a sexually immature, colonial stage after having reached sexual maturity as a solitary individual. Others include the jellyfish Laodicea undulata and species of the genus Aurelia.
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.
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.
Porpita porpita, or the blue button, is a marine organism consisting of a colony of hydroids found in the warmer, tropical and sub-tropical waters of the Pacific, Atlantic, and Indian oceans, as well as the Mediterranean Sea and eastern Arabian Sea. It was first identified by Carl Linnaeus in 1758, under the basionym Medusa porpita. In addition, it is one of the two genera under the suborder Chondrophora, which is a group of cnidarians that also includes Velella. The chondrophores are similar to the better-known siphonophores, which includes the Portuguese man o' war, or Physalia physalis. Although it is superficially similar to a jellyfish, each apparent individual is actually a colony of hydrozoan polyps. The taxonomic class, Hydrozoa, falls under the phylum Cnidaria, which includes anemones, corals, and jellyfish, which explains their similar appearances.
Haleciidae is a family of hydrozoans. Their hydroid colonies emerge from a creeping hydrorhiza and usually form upright branching colonies, although some species' colonies are stolonal. Their gonophores are typically sporosacs, growing singly or bunched into a glomulus. They remain attached to the hydroids or break off to be passively drifted away; in a few, the gonophores are naked.
Marrus orthocanna is a species of pelagic siphonophore, a colonial animal composed of a complex arrangement of zooids, some of which are polyps and some medusae. Swimming independently in the mid-ocean, it lives in the Arctic and other cold, deep waters. It is a colonial creature that is born from a single egg which is fertilized. Later on, a protozoan forms that eventually grows to form more duplicating members of the colony. It belongs to the order Siphonophorae and the genus Marrus, which also includes M. antarcticus, M. claudanielis, and M. orthocannoides.
Tubularia indivisa is a species of large hydroid discovered in 1758.
Eudendrium ramosum, sometimes known as the tree hydroid, is a marine species of cnidaria, a hydroid (Hydrozoa) in the family Eudendriidae of the order Anthoathecata.
Obelia longissima is a colonial species of hydrozoan in the order Leptomedusae. Its hydroid form grows as feathery stems resembling seaweed from a basal stolon. It is found in many temperate and cold seas world-wide but is absent from the tropics.
The tubular sponge hydroid is a species of hydroid cnidarian. It is a member of the family Tubulariidae. These animals usually grow embedded in sponges.
Paragorgia arborea is a species of coral in the family Paragorgiidae, commonly known as the bubblegum coral because of its bulbous branch tips. It mainly grows in depths between 200 and 1,300 metres at temperatures between 3 and 8 °C. It is found widespread in the Northern Atlantic Ocean and Northern Pacific Ocean on seamounts and knolls, and was first described by the Swedish naturalist Carl Linnaeus in 1758. P. arborea is a foundation species, providing a habitat for other species in deep sea coral ecosystems.
Pennaria disticha, also known as the Christmas tree hydroid, is a species of athecate hydroid in the family Pennariidae. Colonies are common in the Mediterranean Sea growing on rocks close to the surface. This species has been used in research into prey capture.
Sertularella polyzonias is a branching colonial hydroid in the family Sertulariidae.
Halecium muricatum, commonly known as the sea hedgehog hydroid, is a species of hydrozoan in the family Haleciidae. It occurs mainly in arctic and northern temperate waters, in both the Atlantic and Pacific Oceans.
Obelia dichotoma is a broadly distributed, mainly marine but sometimes freshwater, colonial hydrozoan in the order Leptothecata that forms regular branching stems and a distinctive hydrotheca. O. dichotoma can be found in climates from the arctic to the tropics in protected waters such as marches and creeks but not near open coasts like beaches in depths up to 250m. O. dichotoma uses asexual and sexual reproduction and feeds on mainly zooplankton and fecal pellets. Obelia dichotoma has a complex relationship with the ecosystem and many economic systems.
Rosalindidae is a family of cnidarians belonging to the order Anthoathecata.
Halisiphonia is a genus of deep water hydrozoans belonging to the family Hebellidae. There is little known about individual species. This lack of information has resulted from the difficulty of studying members of this genus due to the great depths at which they are located.
The epibiotic hydroid is a benthic species within the Cnidaria phylum which is distributed throughout the Western Atlantic Ocean.