|
Errantia
Errantia is a diverse group of marine polychaete worms in the phylum Annelida. Traditionally a subclass of the paraphyletic class "Polychaeta", it is currently regarded as a monophyletic group within the larger Pleistoannelida, composed of Errantia and Sedentaria. These worms are found worldwide in marine environments and brackish water. Phylogeny The phylogeny of polychaetes is slowly being resolved. Errantia and Sedentaria are the two biggest clades of polychaetes, and together they compose clade Pleistoannelida. Two groups are nested within Errantia: Aciculata (Eunicida + Phyllodocida) and Protodriliformia (small meiofaunal worms such as the Protodrilida). Historically, the order Amphinomida was part of this subclass. However, phylogenetic analyses place Amphinomida inside a basal clade with Sipunculida and '' Lobatocerebrum'', and this clade is the sister group to Pleistoannelida. Some taxa, such as Spintheridae and Myzostomida, are still difficult to place due to their lon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aciculata
Errantia is a diverse group of marine polychaete worms in the phylum Annelida. Traditionally a subclass of the paraphyletic class "Polychaeta", it is currently regarded as a monophyletic group within the larger Pleistoannelida, composed of Errantia and Sedentaria. These worms are found worldwide in marine environments and brackish water. Phylogeny The phylogeny of polychaetes is slowly being resolved. Errantia and Sedentaria are the two biggest clades of polychaetes, and together they compose clade Pleistoannelida. Two groups are nested within Errantia: Aciculata (Eunicida + Phyllodocida) and Protodriliformia ( small meiofaunal worms such as the Protodrilida). Historically, the order Amphinomida was part of this subclass. However, phylogenetic analyses place Amphinomida inside a basal clade with Sipunculida and '' Lobatocerebrum'', and this clade is the sister group to Pleistoannelida. Some taxa, such as Spintheridae and Myzostomida, are still difficult to place due to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pleistoannelida
Pleistoannelida is a group of annelid worms that comprises the vast majority of the diversity in phylum Annelida. Discovered through phylogenetic analyses, it is the largest clade of annelids, comprised by the last common ancestor of the highly diverse sister groups Errantia and Sedentaria (Clitellata and related polychaetes) and all the descendants of that ancestor. Phylogeny Pleistoannelida is composed by two big clades: Errantia (Eunicida, eunicids, siboglinids and related polychaetes) and Sedentaria (spoon worms, Siboglinidae, tubeworms, clitellates and related polychaetes). There are also smaller groups of difficult placement, such as Myzostomida and Spintheridae, that belong to either one of them. Closely related to Pleistoannelida is a grade of basal annelids: the Amphinomida/Sipunculida/''Lobatocerebrum'' clade, Chaetopterida and Palaeoannelida. A possible, closer sister group to Pleistoannelida could be Dinophiliformia, a clade containing interstitial (meiofaunal) genera p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedentaria
Sedentaria is a diverse clade of annelid worms. It is traditionally treated as a subclass of the paraphyletic class Polychaeta, but it is also a monophyletic group uniting several polychaetes and the monophyletic class Clitellata. It is the sister group of Errantia. Phylogeny The phylogeny of polychaetes is slowly being resolved. Sedentaria and Errantia are the two biggest clades of polychaetes, and together they compose clade Pleistoannelida. Sedentaria's most basal clade is Orbiniida. Other groups that are nested within Sedentaria are: Clitellata, the Sabellida/Spionida clade, Opheliida, Echiura, Cirratuliformia, Terebelliformia, Maldanomorpha and the families Siboglinidae and Capitellidae. Some taxa, such as Spintheridae and Myzostomida, are still difficult to place due to their long branching, but they likely belong to either Errantia Errantia is a diverse group of marine polychaete worms in the phylum Annelida. Traditionally a subclass of the paraphyletic class "Polycha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protodriliformia
Protodriliformia is a clade of small marine life, marine polychaetes, comprised by the groups of meiofaunal interstitial worms Protodrilida and Polygordiidae, formerly considered "archiannelida, archiannelids". It is the most basal clade of Errantia. Evolutionary history Phylogenetic analysis of annelids has found Protodriliformia to be the earliest diverging clade of Errantia. At the same time, the other half of "archiannelid" worms, Orbiniida, was found to be the earliest diverging clade of Sedentaria. The Convergent evolution, convergence between these two groups occurred through progenesis and miniaturization, as a way to adapt to the marine interstitial ecosystem between sand grains (i.e. interstitium). This means that the larval or juvenile stages of a larger pleistoannelida, pleistoannelid ancestor temporarily inhabiting the interstitium stopped their somatic cell, somatic growth, became Sexual maturity, sexually mature and stayed in the interstitium permanently. Reference ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eunicidae
Eunicidae is a family of marine polychaetes (bristle worms). The family comprises marine annelids distributed in diverse benthic habitats across Oceania, Europe, South America, North America, Asia and Africa. The Eunicid anatomy typically consists of a pair of appendages near the mouth (mandibles) and complex sets of muscular structures on the head (maxillae) in an eversible pharynx. One of the most conspicuous of the eunicids is the giant, dark-purple, iridescent " Bobbit worm" (''Eunice aphroditois''), a bristle worm found at low tide under boulders on southern Australian shores. Its robust, muscular body can be as long as 2 m. Eunicidae jaws are known from as far back as Ordovician sediments. Cultural tradition surrounds Palola worm (''Palola viridis'') reproductive cycles in the South Pacific Islands. Eunicidae are economically valuable as bait in both recreational and commercial fishing. Commercial bait-farming of Eunicidae can have adverse ecological impacts. Bait-far ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phyllodocida
Phyllodocida is an order of polychaete worms in the subclass Aciculata. These worms are mostly marine, though some are found in brackish water. Most are active benthic creatures, moving over the surface or burrowing in sediments, or living in cracks and crevices in bedrock. A few construct tubes in which they live and some are pelagic, swimming through the water column. There are estimated to be more than 4,600 accepted species in the order. Characteristics Phyllodocida are segmented worms and range in size from a few millimetres long to over a metre. Each segment bears a pair of paddle-like parapodia. The prostomium generally has one or two pairs of eyes, a dorsal pair of antennae, a ventral pair of sensory palps and a pair of organs on the neck. The peristomium is a ring, often hidden dorsally by the prostomium and the first segment. There is a muscular proboscis with one or more pairs of jaws. The next few segments tend to differ from those further back in having enlarged do ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eunicida
Eunicida is an order of polychaete worms. Characteristics Members of this order have an elongated, segmented body and a distinct head, normally with a separate peristomium and prostomium. Many, but not all, live in tubes which vary from a mucous sheath to a tough, horny casing. The palps vary from globular to cylindrical and there are from 0 to 7 antennae, usually smooth but occasionally jointed. There is a muscular pharynx with a dorsal pair of mandibles and a set of ventral, toothed, maxillary plates. Some species have tentacular cirri and all have unbranched parapodia. In some species, dorsal cirri, branchiae, ventral cirri and chaetae occur, but not in others. Natural History Museum. Retrieved 2012-01-17. Fossil record The |
Polychaete
Polychaeta () is a paraphyletic class (biology), class of generally marine invertebrate, marine annelid worms, common name, commonly called bristle worms or polychaetes (). 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 (''Arenicola marina'') and the Alitta virens, sandworm or Alitta succinea, clam worm ''Alitta''. Polychaetes as a class are robust and widespread, with species that live in the coldest ocean temperatures of the abyssal plain, to forms which tolerate the extremely high temperatures near hydrothermal vents. Polychaetes occur throughout the Earth's oceans at all depths, from forms that live as plankton near the surface, to a 2- to 3-cm specimen (still unclassified) observed by the robot ocean probe Nereus (underwater vehicle), ''Nereus'' at the bottom of the Challenger Deep, the deepes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euphrosinidae
The Euphrosinidae are a family of polychaete worms. The name is from Greek ''Euphrosyne'', meaning merriment; she was one of the three Graces. Clade Species ''Euphrosinidae'' contains the following genera and species: *''Euphrosine'' Lamarck, 1818 ** '' Euphrosine abyssalis'' Kudenov, 1993 ** '' Euphrosine affinis'' Horst, 1903 ** '' Euphrosine arctia'' Johnson, 1897 ** '' Euphrosine armadillo'' Sars, 1851 ** '' Euphrosine armadilloides'' Ehlers, 1900 ** '' Euphrosine armata'' Kudenov, 1993 ** '' Euphrosine aurantiaca'' Johnson, 1897 ** '' Euphrosine bicirrata'' Moore, 1905 ** '' Euphrosine borealis'' Örstedt, 1843 ** ''Euphrosine calypta'' Essenberg, 1917 ** ''Euphrosine capensis'' Kinberg, 1857 ** ''Euphrosine ceylonica'' Michaelsen, 1892 ** ''Euphrosine cirrata'' Sars, 1862 ** ''Euphrosine cirrataepropinqua'' Amoureux, 1982 ** ''Euphrosine cirribranchis'' Hartmann-Schröder & Rosenfeldt, 1992 ** '' Euphrosine digitalis'' Imajima, 2009 ** '' Euphrosine dumosa'' Moore, 1911 * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polychaeta
Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). 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 (''Arenicola marina'') and the sandworm or clam worm ''Alitta''. Polychaetes as a class are robust and widespread, with species that live in the coldest ocean temperatures of the abyssal plain, to forms which tolerate the extremely high temperatures near hydrothermal vents. Polychaetes occur throughout the Earth's oceans at all depths, from forms that live as plankton near the surface, to a 2- to 3-cm specimen (still unclassified) observed by the robot ocean probe ''Nereus'' at the bottom of the Challenger Deep, the deepest known spot in the Earth's oceans. Only 168 species (less than 2% of all polychaetes) are known from f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spintheridae
Spintheridae is a family of marine polychaete worms with a single genus, ''Spinther'', containing these species: * '' Spinther alaskensis'' Hartman, 1948 * '' Spinther arcticus'' (M. Sars, 1851) (includes Spinther miniaceus'' Grube, 1860) *'' Spinther australiensis'' Augener, 1913 * '' Spinther citrinus'' (Stimpson, 1854) *'' Spinther ericinus'' Yamamoto & Imajima, 1985 *'' Spinther hystrix'' Uschakov, 1950 * '' Spinther japonicus'' Imajima and Hartman, 1964 * '' Spinther oniscoides'' Johnston, 1845 *'' Spinther sagamiensis'' Imajima, 2003 *'' Spinther usarpia'' Hartman, 1967 * '' Spinther vegae'' Augener, 1928 (includes '' Spinther wireni'' Hartman, 1948) The animal lives as a symbiont on sponges. Johnston's paper does not explain the choice of the name, but ancient Greek σπινθήρ means "spark." In images of the living animal, it appears to be surrounded by a cloud of pinpoints of light. References Polychaetes Taxa named by George Johnston (naturalist) {{anne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sister Group
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and taxon B are sister groups to each other. Taxa A and B, together with any other extant or extinct descendants of their most recent common ancestor (MRCA), form a monophyletic group, the clade AB. Clade AB and taxon C are also sister groups. Taxa A, B, and C, together with all other descendants of their MRCA form the clade ABC. The whole clade ABC is itself a subtree of a larger tree which offers yet more sister group relationships, both among the leaves and among larger, more deeply rooted clades. The tree structure shown connects through its root to the rest of the universal tree of life. In cladistic standards, taxa A, B, and C may represent specimens, species, genera, or any other taxonomic units. If A and B are at the same taxonomic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.png "Click for more on -> Sister Group")