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In animals, viviparity is development of the embryo inside the body of the mother, with the maternal circulation providing for the metabolic needs of the embryo's development, until the mother gives birth to a fully or partially developed juvenile that is at least metabolically independent. This is opposed to oviparity, where the embryos develop independently outside the mother in eggs until they are developed enough to break out as hatchlings; and ovoviviparity, where the embryos are developed in eggs that remain carried inside the mother's body until the hatchlings emerge from the mother as juveniles, similar to a live birth.
Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop inside eggs that remain in the mother's body until they are ready to hatch.
Stomiiformes is an order of deep-sea ray-finned fishes of very diverse morphology. It includes, for example, dragonfishes, lightfishes, loosejaws, marine hatchetfishes and viperfishes. The order contains 4 families with more than 50 genera and at least 410 species. As usual for deep-sea fishes, there are few common names for species of the order, but the Stomiiformes as a whole are often called dragonfishes and allies or simply stomiiforms.
The olm or proteus is an aquatic salamander which is the only species in the genus Proteus of the family Proteidae and the only exclusively cave-dwelling chordate species found in Europe; the family's other extant genus is Necturus. In contrast to most amphibians, it is entirely aquatic, eating, sleeping, and breeding underwater. Living in caves found in the Dinaric Alps, it is endemic to the waters that flow underground through the extensive limestone bedrock of the karst of Central and Southeastern Europe in the basin of the Soča River near Trieste, Italy, southern Slovenia, southwestern Croatia, and Bosnia and Herzegovina. Introduced populations are found near Vicenza, Italy, and Kranj, Slovenia. It was first mentioned in 1689 by the local naturalist Valvasor in his Glory of the Duchy of Carniola, who reported that, after heavy rains, the olms were washed up from the underground waters and were believed by local people to be a cave dragon's offspring.
In biology, gonochorism is a sexual system where there are two sexes and each individual organism is either male or female. The term gonochorism is usually applied in animal species, the vast majority of which are gonochoric.
Fish reproductive organs include testes and ovaries. In most species, gonads are paired organs of similar size, which can be partially or totally fused. There may also be a range of secondary organs that increase reproductive fitness. The genital papilla is a small, fleshy tube behind the anus in some fishes, from which the sperm or eggs are released; the sex of a fish can often be determined by the shape of its papilla.
The black dogfish is a species of dogfish shark in the family Etmopteridae. It is common over the outer continental shelf and continental slope at depths of 180–2,250 m (590–7,380 ft). Females generally inhabit deeper water than males, and depending on the region, smaller sharks may occur at different depths than larger ones. This species is distributed widely in the Atlantic Ocean, from Greenland and Iceland to Virginia and West Africa in the north, and off southwestern Africa and Argentina in the south. The largest member of its family, the black dogfish, typically measures 60–75 cm (24–30 in) long. It has a stocky, dark brown body that is darker below than above, and bears scattered, minute bioluminescent organs. Its two dorsal fins are preceded by stout spines, and the anal fin is absent.
Zoarcoidei is a suborder of marine ray-finned fishes belonging to the order Perciformes. The suborder includes the wolffishes, gunnels and eelpouts. The suborder includes about 400 species. These fishes predominantly found in the boreal seas of the northern hemisphere but they have colonised the southern hemisphere.
Tardigrades, known colloquially as water bears or moss piglets, are a phylum of eight-legged segmented micro-animals. They were first described by the German zoologist Johann August Ephraim Goeze in 1773, who called them Kleiner Wasserbär'little water bear'. In 1776, the Italian biologist Lazzaro Spallanzani named them Tardigrada, which means 'slow walker'.
Anableps anableps, the largescale four-eyes, is a species of four-eyed fish found in fresh and brackish waters of northern South America and Trinidad. This species grows to a length of 30 centimetres (12 in) total length (TL). This fish can occasionally be found in the aquarium trade. The fish does not actually have four eyes. Instead, each eye is split into two lobes by a horizontal band of tissue, each lobe with its own pupil and separate vision. This allows the fish to see above and below the surface of the water at the same time. This species has been documented to occasionally feed on land. Both sexes exhibit asymmetrical genitalia.
The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are also important accessories to the reproductive system. Unlike most organ systems, the sexes of differentiated species often have significant differences. These differences allow for a combination of genetic material between two individuals, which allows for the possibility of greater genetic fitness of the offspring.
Saiphos equalis, commonly known as the yellow-bellied three-toed skink or simply three-toed skink, is a species of burrowing skink found in eastern Australia. It is the only species classified under the genus Saiphos.
Louis Michel François Doyère was a French zoologist and agronomist.
Zenarchopteridae, the viviparous halfbeaks, is a family of ray-finned fishes in the order Beloniformes. The Zenarchopteridae exhibit strong sexual dimorphism, practicing internal fertilisation, and in some cases ovoviviparous or viviparous. The members in the family are mainly found in fresh and brackish water of tropical Asia and New Guinea, but the genus Zenarchopterus also includes marine species from the Indo-Pacific. Several, such as the wrestling halfbeak, have become commonly traded aquarium fish.
Ernst Gustav Gotthelf Marcus was a German zoologist, occupant of the chair of zoology at the University of São Paulo from 1936 to 1963, and co-founder of the Oceanographic Institute of the University of São Paulo.
Pregnancy has been traditionally defined as the period of time eggs are incubated in the body after the egg-sperm union. Although the term often refers to placental mammals, it has also been used in the titles of many international, peer-reviewed, scientific articles on fish. Consistent with this definition, there are several modes of reproduction in fish, providing different amounts of parental care. In ovoviviparity, there is internal fertilization and the young are born live but there is no placental connection or significant trophic (feeding) interaction; the mother's body maintains gas exchange but the unborn young are nourished by egg yolk. There are two types of viviparity in fish. In histotrophic viviparity, the zygotes develop in the female's oviducts, but she provides no direct nutrition; the embryos survive by eating her eggs or their unborn siblings. In hemotrophic viviparity, the zygotes are retained within the female and are provided with nutrients by her, often through some form of placenta.
David M. Sever is an American herpetologist, histologist, anatomist and reproductive biologist. He has been a professor and department head in the Department of Biological Sciences at Southeastern Louisiana University since 2004, and held the Kenneth Dyson Endowed Professorship in Biological Sciences from 2012 to 2015. He is well known for over 30 years of research on the secondary sexual characteristics of salamanders and more generally on comparative histoanatomy of the urogenital systems of vertebrates. and was recognized as the 2013 Distinguished Herpetologist of the Year by the Herpetologists' League.
Arthrotardigrada are an order of tardigrades, first described by Ernst Marcus in 1927.
Erna W. Mohr was a German zoologist who made contributions to ichthyology and mammalogy. Mohr was long associated with the Zoological Museum Hamburg, where she was successively head of the Fish Biology Department, Department of Higher Vertebrates, and Curator of the Vertebrate Department. She was a member of the Academy of Sciences Leopoldina and held an honorary doctorate from the University of Munich.
The Atherinomorpha is a clade of fishes in the superorder Acanthopterygii, the ray-finned fishes, consisting of three orders. The clade is ranked as an infraseries within the subseries Ovalentaria, which in turn is ranked within the wider Percomorpha clade.
References
- ↑ "Society for Ichthyology (GfI)", March 26, 2021.