| Spionida | |
|---|---|
 | |
| Magelona johnstoni with long feeding palps. | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Annelida |
| Class: | Polychaeta |
| Infraclass: | Canalipalpata |
| Order: | Spionida |
| Families | |
Several, see text | |
Spionida is an order of marine polychaete worms in the infraclass Canalipalpata. Spionids are cosmopolitan and live in soft substrates in the littoral or neritic zones. [1]
Spionids have a single pair of flexible feeding tentacles with grooves, arising directly from the prostomium. The mouth has no jaws and the pharynx is partly eversible. Some species have small eye spots and some a central sensory lobe. Some of the anterior segments paired gills. The parapodia or lateral lobes have large lamellae. The chaetae are unbranched capillaries, spines and hooks. [1] [2]
According to the World Register of Marine Species (WoRMS), the Spionida comprises six families in a single suborder: [3]
Other families such as Aberrantidae and Magelonidae are sometimes included in Spionida. [5]
The Polychaeta, also known as the bristle worms or polychaetes, are a paraphyletic class of annelid worms, generally marine. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. More than 10,000 species are described in this class. Common representatives include the lugworm and the sandworm or clam worm Alitta.
The Scorpaeniformes are a diverse order of ray-finned fish, including the lionfish, but have also been called the Scleroparei. It is one of the five largest orders of bony fishes by number of species, with over 1,320.
Isopoda is an order of crustaceans that includes woodlice and their relatives. Isopods live in the sea, in fresh water, or on land. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, and five pairs of branching appendages on the abdomen that are used in respiration. Females brood their young in a pouch under their thorax.
The Arcida is an extant order of bivalve molluscs. This order dates back to the lower Ordovician period. They are distinguished from related groups, such as the mussels, by having a straight hinge to the shells, and the adductor muscles being of equal size. The duplivincular ligament, taxodont dentition, and a shell microstructure consisting of the outer crossed lamellar and inner complex crossed lamellar layers are defining characters of this order.
Zoanthids are an order of cnidarians commonly found in coral reefs, the deep sea and many other marine environments around the world. These animals come in a variety of different colonizing formations and in numerous colors. They can be found as individual polyps, attached by a fleshy stolon or a mat that can be created from small pieces of sediment, sand and rock. The term "zoanthid" refers to all animals within this order Zoantharia, and should not be confused with "Zoanthus", which is one genus within Zoantharia.
Alcyonacea, or soft corals, are an order of corals. In addition to the fleshy soft corals, the order Alcyonacea now contains all species previously known as "gorgonian corals", that produce a more or less hard skeleton, though quite different from "true" corals (Scleractinia). These can be found in suborders Holaxonia, Scleraxonia, and Stolonifera. They are sessile colonial cnidarians that are found throughout the oceans of the world, especially in the deep sea, polar waters, tropics and subtropics. Common names for subsets of this order are sea fans and sea whips; others are similar to the sea pens of related order Pennatulacea. Individual tiny polyps form colonies that are normally erect, flattened, branching, and reminiscent of a fan. Others may be whiplike, bushy, or even encrusting. A colony can be several feet high and across, but only a few inches thick. They may be brightly coloured, often purple, red, or yellow. Photosynthetic gorgonians can be successfully kept in captive aquaria.
Heterodonta is a taxonomic subclass of saltwater clams, marine bivalve molluscs. This subclass includes the edible clams, the cockles and the Venus clams.
The starry smooth-hound is a houndshark of the family Triakidae. It is found on the continental shelves of the northeast Atlantic, between latitudes 61° N and 16° N, from the surface to a depth of 200 m (660 ft). It can grow up to a length of 1.4 m.
The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive list of names of marine organisms.
Scleraxonia is a suborder of corals, a member of the phylum Cnidaria.
Holaxonia is a suborder of soft corals, a member of the phylum Cnidaria. Members of this suborder are sometimes known as gorgonians and include the sea blades, the sea fans, the sea rods and the sea whips. These soft corals are colonial, sessile organisms and are generally tree-like in structure. They do not have a hard skeleton composed of calcium carbonate but have a firm but pliable, central axial skeleton composed of a fibrous protein called gorgonin embedded in a tissue matrix, the coenenchyme. In some genera this is permeated with a calcareous substance in the form of fused spicules. Members of this suborder are characterized by having an unspiculated axis and often a soft, chambered central core. The polyps have eight-fold symmetry and in many species, especially in the families Gorgoniidae and Plexauridae, contain symbiotic photosynthetic algae called zooxanthellae. These soft corals are popular in salt water aquaria.
Caprelloidea is a superfamily of marine crustaceans in the order Amphipoda. It includes "untypical" forms of amphipods, such as the skeleton shrimps (Caprellidae) and whale lice (Cyamidae). The group was formerly treated as one of the four amphipod suborders, Caprellidea, but has been moved down to the superfamily rank by Myers & Lowry after phylogenetic studies of the group, and is now contained in the infraorder Corophiida of the suborder Senticaudata. The group includes the following families.
Shrimp are decapod crustaceans with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata. More narrow definitions may be restricted to Caridea, to smaller species of either group or to only the marine species. Under a broader definition, shrimp may be synonymous with prawn, covering stalk-eyed swimming crustaceans with long, narrow muscular tails (abdomens), long whiskers (antennae), and slender legs. Any small crustacean which resembles a shrimp tends to be called one. They swim forward by paddling with swimmerets on the underside of their abdomens, although their escape response is typically repeated flicks with the tail driving them backwards very quickly. Crabs and lobsters have strong walking legs, whereas shrimp have thin, fragile legs which they use primarily for perching.
Leucotheidae is a family of ctenophores. It contains a single genus, Leucothea.
Ganesha is a genus of comb jellies. It is the only genus in the monotypic family Ganeshidae and the order Ganeshida. They are characterized by pair of small lobes round the mouth, and extended pharynx. Two species are currently recognized: Ganesha elegans and Ganesha annamita.
Cyrtocrinida is an order of sea lilies which contains two suborders and three families.
Hoplonemertea is an order of ribbon worms in the class Enopla. It contains two suborders:
Echiurida is a suborder of the order Echiuroidea, an order of polychaete worms.
Thigmophryidae is a family of marine ciliates in the order Philasterida.
Anuropus is a genus of isopods in the suborder Cymothoida. As of 2021, it is the only genus in the family Anuropidae.
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