Clasper

In biology, a clasper is a male anatomical structure found in some groups of animals, used in mating.

Spotted Ratfish Clasper
A close up ventral view of a chimaera clasper (Hydrolagus collie). Note the many small tooth-like projections covering the exterior surface.

Male cartilaginous fish have claspers formed from the posterior portion of their pelvic fin which serve as intromittent organs used to channel semen into the female's cloaca during mating. The act of mating in some fish including sharks usually includes one of the claspers raised to allow water into the siphon through a specific orifice. The clasper is then inserted into the cloaca, where it opens like an umbrella to anchor its position. The siphon then begins to contract, expelling water and sperm.[1][2] Male chimaeras have cephalic claspers (tenacula) on their heads, which are thought to aid in holding the female during mating.

In entomology, it is a structure in male insects that is used to hold the female during copulation (see Lepidoptera genitalia for more).

Wobbegong claspers
The claspers of a spotted wobbegong shark (Orectolobus maculatus)
Carcharhinus brevipinna JNC3077 Male parts
The claspers of a young spinner shark (Carcharhinus brevipinna)

See also

References

  1. ^ "System glossary". FishBase. Retrieved 2013-02-15.
  2. ^ Heinicke, Matthew P.; Naylor, Gavin J. P.; Hedges, S. Blair (2009). The Timetree of Life: Cartilaginous Fishes (Chondrichthyes). Oxford University Press. p. 320. ISBN 0191560154.
Aedeagus

An aedeagus (plural aedeagi) is a reproductive organ of male arthropods through which they secrete sperm from the testes during copulation with a female. Very loosely, it can be thought of as the insect equivalent of a mammal's penis, though the matter is actually more complex.

The aedeagus is part of the male's abdomen, which is the hindmost of the three major body sections of an insect. The pair of testes of the insect are connected to the aedeagus through the genital ducts. The aedeagus is part of the male insect's phallus, a complex and often species-specific arrangement of more or less sclerotized (hardened) flaps and hooks which also includes in some species the valvae (clasper), which are paired organs which help the male hold on to the female during copulation. During copulation, the aedeagus connects with the ovipore of a female. The aedeagus can be quite pronounced or de minimis.

The base of the aedeagus may be the partially sclerotized phallotheca, also called the

phallosoma or theca. In some species the phallotheca contains a space, called the endosoma (internal holding pouch), into which the tip end of the aedeagus may be withdrawn (retracted). The vas deferens is sometimes drawn into (folded into) the phallotheca together with a seminal vesicle.The sperm of arthropods is not passed to the female as liquid with free-swimming spermatozoa, but contains capsules called spermatophores in which the actual spermatozoa are enclosed. In addition to the spermatophores, in some species the aedeagus also discharges a spermatophylax, a ball of nutritious secretions to aid the female in producing offspring.

In males of most species of Lepidoptera, the aedeagus has a sheath which is supported by an organ called the juxta, which is located between the aforementioned valvae.

Atwater-Donnelly

Atwater-Donnelly is a Rhode Island folk music group consisting of Aubrey Atwater, Elwood Donnelly, and occasionally other musicians and dancers. They have toured throughout the United States and internationally, playing guitar, banjo, Appalachian dulcimer, tin whistle, limberjack, and other instruments. In recent years, they have also performed as The Atwater-Donnelly Trio, with Cathy Clasper-Torch.

Atwater and Donnelly met as volunteers at the Stone Soup Coffeehouse in Rhode Island in early 1987, and started playing together a few months later. They specialize in traditional American folk music and Celtic folk music, but write and play their own songs as well. Their performances have been featured on All Songs Considered and Fiona Ritchie's The Thistle & Shamrock on public radio. Atwater regularly runs workshops at places like the John C. Campbell Folk School, as well as performing and teaching clogging and flat-footing dance, derived mainly from dance steps learned in Appalachia and the southeast U.S.

They were one of the earlier musical groups to be on the web, after one of their fans worked with Atwater to put a site up in 1995.They have released 13 albums, several books of poetry, and two songbooks.

Atwater was selected to serve as Artist-in-residence at the Grand Canyon National Park in May–June 2011.

Clasp

Clasp, clasper or CLASP may refer to:

Wrist clasp, a dressing accessory

Folding clasp, a device used to close a watch strap

Medal bar, an element in military decoration

Fastener, a hardware device that mechanically joins objects together

"Clasp", a track from Jethro Tull's album The Broadsword and the Beast

Clasper, an anatomical structure in male cartilaginous fish

Clasper (mathematics), a surface (with extra structure) in a 3-manifold on which surgery can be performed

Grasp, holding or seizing firmly with (or as if with) the hand

Clasper (mathematics)

In the mathematical field of low-dimensional topology, a clasper is a surface (with extra structure) in a 3-manifold on which surgery can be performed.

Clasper v Lawrence

Clasper v Lawrence [1990] 3 NZLR 231 is a cited case in New Zealand regarding the quantification of damages for breach of contract.

HMS Philomel (1842)

HMS Philomel was an eight-gun Alert-class packet brig of the Royal Navy, built between 1840 and 1842. Ships of this class were designed by William Symonds in 1834, and the Philomel was built at Plymouth.

The vessel launched in 1842 as a surveying vessel, and by 1857 was given over to the coastguard and renamed CGWV.23.

It foundered in the Swale in 1869, and the wreck was sold to Hayhurst & Clasper as salvage. It was finally broken up on 26 February 1870.

The Falkland Islands issued a set of stamps in 1985 for "Early Cartographers maps", the ship is featured on the fourth in set, 54p stamp along with Admiral Sir B. J. Sulivan K.C.B.

Harpago

Harpago is a genus of sea snails, marine gastropod mollusks in the family Strombidae, the true conchs.Harpago ('grappling iron') is also a term used in insect morphology for the distal end of a genital clasper.

Harry Clasper

Harry Clasper (5 July 1812 – 12 July 1870) was a professional rower and boat builder from Tyneside in England. He was an innovative boat designer who pioneered the development of the racing shell and the use of outriggers. He is said to have invented spoon-shaped oars.He was the first of three well-known Tyneside oarsmen, the other two being Robert Chambers and James Renforth.

Incisoscutum

Incisoscutum is a genus of arthrodire placoderm from the Late Frasnian Gogo Reef, from Late Devonian Australia. The genus contains two species I. ritchiei, named after Dr. Alex Ritchie, a palaeoichthyologist and senior fellow of the Australian Museum, and I. sarahae, named after Sarah Long, daughter of its discoverer and describer, Dr. John A. Long.

The genus is important in the study of early vertebrates as well-preserved fossilised embryos have been found in female specimens and ossified pelvic claspers found in males. This shows that viviparity and internal fertilisation was common amongst these primitive jawed vertebrates, which are outside the crown group Gnathostoma.

In a study of fossil remains, comparison of the ontogeny of fourteen dermal plates from Compagopiscis croucheri and the more derived species Incisoscutum ritchiei suggested that lengthwise growth occurs earlier in the ontogeny than growth in width, and that dissociated allometric heterochrony has been an important mechanism in the evolution of the arthrodires, which include placoderms.

These same fossil specimens also show that Incisoscutum was a predator, as muscle fibres from the tails of other placoderms have been found in the stomach regions.

Microbrachius

Microbrachius is an extinct genus of tiny, advanced antiarch placoderms closely related to the bothriolepids. Complete articulated specimens show that the armored section of the body had an average length of 2-4 cm. Species of Microbrachius are characterized by having large heads with short thoracic armor. Specimens of Microbrachius have been found in Scotland, Belarus, Estonia, and China. Specimens range in age from the Lower Devonian Late Emsian Stage (393.3 Ma) to the Middle Devonian Upper Givetian Stage (382.7 Ma).

Although two of the four described species are known from Late Emsian-aged strata of Early Devonian China, the type and youngest species, M. dicki, is known from upper Givetian freshwater strata of Scotland. The various species have short thoracic armor, and large heads. There are patterns of small, but noticeable tubercles on the armor, with the arrangement varying from species to species.

Mike Clasper

Michael Clasper CBE (born 21 April 1953) is the British Chairman of Guinness Peat Group plc (GPG) and the former chairman of Her Majesty's Revenue and Customs (HMRC) (2008-2012).

Parmaturus

Parmaturus is a genus of catshark in the family Scyliorhinidae. Four species were described in 2007 with more species likely to be described in the near future.

Pyraustinae

Pyraustinae is a large subfamily of the lepidopteran family Crambidae, the crambid snout moths. It currently includes over 1,400 species, the majority of them tropical but some found in temperate regions including both North America and Europe.

The Pyraustinae were originally including the Spilomelinae; the present group was at that time considered a tribe Pyraustini. It has not been fully established yet which taxa of the Pyraustinae sensu lato belong to Pyraustinae as currently understood; thus the number of species in this subfamily is set to increase (although the Spilomelinae are the larger group of the old Pyraustinae).

Taxonomists' opinions differ as to the correct placement of the Crambidae, some authorities treating them as a subfamily (Crambinae) of the family Pyralidae. If this is done, Pyraustinae is usually treated as a separate subfamily within Pyralidae.

The Pyraustinae are characterised by atrophied spinula and venulae in the tympanal organs; a narrow fornix tympani; a longitudinal groove with androconial scales on the male mesothoracic tibiae; an often spinose antrum; and a sella (a medially directed clasper on the inside of the valvae), and an editum with modified setae on the male valvae.

Many species have larvae that bore into stems and fruit of plants, and several, notably from the genus Ostrinia, are serious agricultural pests.

Robert Chambers (oarsman)

Robert Chambers (14 June 1831 – 4 June 1868) was a famous Tyneside professional oarsman. He became the Tyne, Thames, English and World Sculling Champion.

He was one of three great Tyneside oarsmen, the other two being Harry Clasper and James Renforth.

Swalwell

Swalwell is a village in Gateshead, Tyne and Wear, England, in the United Kingdom.

Telomere (disambiguation)

A telomere is a region of repetitive nucleotide sequences at each end of a chromosome.

Telomere may also refer to:

Telomere (insect morphology), a type of genital clasper

Telomere resolvase, an enzyme found in bacteria which contain linear plasmids.

The Boat Race 1883

The 40th Boat Race, an annual side-by-side rowing race between crews from the Universities of Oxford and Cambridge along the River Thames, took place on 15 March 1883. Following confusion at the start of the race and a snow storm during the event, Oxford won by a margin of three-and-a-half lengths in a time of 21 minutes 18 seconds.

Vinculum (ligament)

In anatomy, a vinculum (pl. vincula) is a band of connective tissue, similar to a ligament, that connect a flexor tendon to a phalanx bone. They contain tiny vessels which supply blood to the tendon.

In vertebrate anatomy, they are referred to as mesotendons.

For example, in the fingers and toes of humans and related vertebrates, vincula are responsible for the direct vascularization of the flexor digitorum superficialis and profundus tendons to the intermediate and distal phalanges in each finger. These vincula are four folds in the synovial membrane that carry blood vessels to the body and insertion of the tendon. The tendon receives some additional nutrition directly from the synovial fluid in the sheath, which is important in case of partial loss of direct vascularization from the vincula.In the chick, vincula are much larger and more complex than in humans. Though they contain blood vessels, these only make up a very limited portion of the total mass of the vincula, most of whom consists of collagen and elastic fibres.A vinculum is also found in insects' male genitalia. Unlike the vertebrate structures, it is part of the exoskeleton, being formed by the ventral part of the ninth abdominal segment. It retains the aedeagus and the clasper attaches to it.

White-clasper catshark

The white-clasper catshark (Parmaturus albipenis) is a recently described deepwater catshark, known only from a single specimen collected from northern New Caledonia at a depth of 688–732 m. The only known specimen, an adult male, measured a total of 41.5 cm in length.

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