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Annelid Unranked Clades
The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecologies – some in marine environments as distinct as tidal zones and hydrothermal vents, others in fresh water, and yet others in moist terrestrial environments. The Annelids are bilaterally symmetrical, triploblastic, coelomate, invertebrate organisms. They also have parapodia for locomotion. Most textbooks still use the traditional division into polychaetes (almost all marine), oligochaetes (which include earthworms) and leech-like species. Cladistic research since 1997 has radically changed this scheme, viewing leeches as a sub-group of oligochaetes and oligochaetes as a sub-group of polychaetes. In addition, the Pogonophora, Echiura and Sipuncula, previously regarded as separate phyla, are now regarded as sub-groups of polychaetes. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycera (genus)
The genus ''Glycera'' is a group of polychaetes (bristle worms) commonly known as bloodworms. They are typically found on the bottom of shallow marine waters, and some species (e.g. common bloodworms) can grow up to 35 cm (14 in) in length. Anatomy Bloodworms have a creamy pink color, as their pale skin allows their red body fluids that contain haemoglobin to show through. This is the origin of the name "bloodworm". At the 'head', bloodworms have four small antennae and small fleshy projections called parapodia running down their bodies. Bloodworms can grow up to in length. Bloodworms are carnivorous. They feed by extending a large proboscis that bears four hollow jaws. The jaws are connected to glands that supply venom which they use to kill their prey, and their bite is painful even to a human. They are preyed on by other worms, bottom-feeding fish, crustacea, and gulls. Reproduction occurs in midsummer, when the warmer water temperature and lunar cycle among other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siboglinidae
Siboglinidae is a family (biology), family of polychaete Annelida, annelid worms whose members made up the former phylum, phyla Pogonophora and Vestimentifera (the giant tube worms). The family is composed of about 100 species of vermiform creatures which live in thin tubes buried in sediments (Pogonophora) or in tubes attached to hard substratum (Vestimentifera) at ocean depths ranging from . They can also be found in association with hydrothermal vents, methane seeps, sunken plant material, and Whale fall, whale carcasses. The first specimen was dredged from the waters of what is now Indonesia in 1900. These specimens were given to French zoologist Maurice Caullery, who studied them for nearly 50 years. Anatomy Most siboglinids are less than in diameter, but in length. They inhabit tubular structures composed of chitin and fixed to rocks or substrate. The tubes are often clustered together in large colonies. Their bodies are divided into four regions. The anterior end is call ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hirudinea
Leeches are segmented parasitic or predatory worms that comprise the subclass Hirudinea within the phylum Annelida. They are closely related to the oligochaetes, which include the earthworm, and like them have soft, muscular segmented bodies that can lengthen and contract. Both groups are hermaphrodites and have a clitellum, but leeches typically differ from the oligochaetes in having suckers at both ends and in having ring markings that do not correspond with their internal segmentation. The body is muscular and relatively solid, and the coelom, the spacious body cavity found in other annelids, is reduced to small channels. The majority of leeches live in freshwater habitats, while some species can be found in terrestrial or marine environments. The best-known species, such as the medicinal leech, ''Hirudo medicinalis'', are hematophagous, attaching themselves to a host with a sucker and feeding on blood, having first secreted the peptide hirudin to prevent the blood from c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Branchiobdellida
Branchiobdellida is an order of freshwater leech-like clitellates that are obligate ectosymbionts or ectoparasites, mostly of astacoidean crayfish. They are found in the Northern Hemisphere and have a holarctic distribution in East Asia, the Euro-Mediterranean region and North and Central America, with the greatest species diversity being in North and Central America. Taxonomy The exact relationship of this group of clitellates with other groups has been the subject of debate for a century or more. The American zoologist Perry C. Holt wrote his doctoral thesis on branchiobdellids and devoted his 45 years of research to the taxon. With his colleague, the American zoologist Richard L. Hoffman, he described 8 new genera and 75 new species, and re-described various other species. In 1965, he came to the conclusion that the group should be raised from a family to an order, a sister group to the oligochaetes and leeches. Forty years later, molecular data from rDNA and mitochondri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligochaeta
Oligochaeta () is a subclass of animals in the phylum Annelida, which is made up of many types of aquatic and terrestrial worms, including all of the various earthworms. Specifically, oligochaetes comprise the terrestrial megadrile earthworms (some of which are semiaquatic or fully aquatic), and freshwater or semiterrestrial microdrile forms, including the tubificids, pot worms and ice worms ( Enchytraeidae), blackworms ( Lumbriculidae) and several interstitial marine worms. With around 10,000 known species, the Oligochaeta make up about half of the phylum Annelida. These worms usually have few setae (chaetae) or "bristles" on their outer body surfaces, and lack parapodia, unlike polychaeta. Diversity Oligochaetes are well-segmented worms and most have a spacious body cavity (coelom) used as a hydroskeleton. They range in length from less than up to in the 'giant' species such as the giant Gippsland earthworm (''Megascolides australis'') and the Mekong worm (''Amynth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraphyly
In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In contrast, a monophyletic group (a clade) includes a common ancestor and ''all'' of its descendants. The terms are commonly used in phylogenetics (a subfield of biology) and in the tree model of historical linguistics. Paraphyletic groups are identified by a combination of synapomorphies and symplesiomorphies. If many subgroups are missing from the named group, it is said to be polyparaphyletic. The term was coined by Willi Hennig to apply to well-known taxa like Reptilia ( reptiles) which, as commonly named and traditionally defined, is paraphyletic with respect to mammals and birds. Reptilia contains the last common ancestor of reptiles and all descendants of that ancestor, including all extant reptiles as well as the extinct synapsids, ... [...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] |
Clitellata
The Clitellata are a class of annelid worms, characterized by having a clitellum - the 'collar' that forms a reproductive cocoon during part of their life cycles. The clitellates comprise around 8,000 species. Unlike the class of Polychaeta, they do not have parapodia and their heads are less developed. Characteristics Clitellate annelids are segmented worms characterised by the clitellum or girdle which is located near the head end of mature individuals. The mouth is on the ventral surface and is overhung by the prostomium (proboscis). The brain is not located in the head but in one of the body segments. The clitellum is formed by a modification of several segments, and either includes the female gonopores or is located just behind them. During copulation, this glandular tissue secretes mucus that keeps the paired individuals together while they exchange sperm. Afterwards it secretes material that forms a cocoon that encircles the animal's body and encloses the eggs and sperm. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maldanomorpha
Maldanomorpha is a monophyletic group, or clade, of polychaete worms in the phylum Annelida. Several phylogenetic analyses based on morphology (biology), morphological and molecular phylogeny, molecular data have shown that this clade unites the families Arenicolidae and Maldanidae. The two main synapomorphy, synapomorphies, morphological characters described to unite both families, are a Marine_larval_ecology#Larval_development_strategies, lecithotrophic larval development and the presence of an uncinus, a hook-like structure with barbs. References {{Annelid-stub Polychaetes Animals described in 1995 Annelid unranked clades ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terebelliformia
Terebelliformia is a group of 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 ... worms in the phylum Annelida. Phylogeny The internal relationships within the clade Terebelliformia are the following: References Polychaetes {{Annelid-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capitellidae
Capitellidae is a polychaete worm family in the subclass Scolecida. Genera * ''Abyssocapitella'' * ''Amastigos'' * ''Anotomastus'' * ''Baldia (worm), Baldia'' * ''Barantolla'' * ''Branchiocapitella'' * ''Capitella'' * ''Capitellethus'' * ''Capitobranchus'' * ''Dasybranchetus'' * ''Dasybranchus'' * ''Decamastus'' * ''Ditrocha'' * ''Dodecaseta'' * ''Eunotomastus'' * ''Heteromastides'' * ''Heteromastus'' * ''Leiocapitella'' * ''Leiocapitellides'' * ''Leiochrides'' * ''Leiochrus'' * ''Lumbricomastus'' * ''Mastobranchus'' * ''Mediomastus'' * ''Neoheteromastus'' * ''Neomediomastus'' * ''Neonotomastus'' * ''Neopseudocapitella'' * ''Nonatus'' * ''Notodasus'' * ''Notomastus'' * ''Octocapitella'' * ''Paracapitella'' * ''Paraleiocapitella'' * ''Parheteromastides'' * ''Parheteromastus'' * ''Peresiella'' * ''Protomastobranchus'' * ''Pseudocapitella'' * ''Pseudoleiocapitella'' * ''Pseudomastus'' * ''Pseudonotomastus'' * ''Pulliella'' * ''Rashgua'' * ''Scyphoproctus'' * ''Undecimastus'' Refe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echiura
The Echiura, or spoon worms, are a small group of marine animals. Once treated as a separate phylum, they are now considered to belong to Annelida. Annelids typically have their bodies divided into segments, but echiurans have secondarily lost their segmentation. The majority of echiurans live in burrows in soft sediment in shallow water, but some live in rock crevices or under boulders, and there are also deep sea forms. More than 230 species have been described. Spoon worms are cylindrical, soft-bodied animals usually possessing a non-retractable proboscis which can be rolled into a scoop-shape to feed. In some species the proboscis is ribbon-like, longer than the trunk and may have a forked tip. Spoon worms vary in size from less than a centimetre in length to more than a metre. Most are deposit feeders, collecting detritus from the sea floor. Fossils of these worms are seldom found and the earliest known fossil specimen is from the Upper Carboniferous ( Pennsylvanian). T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
