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Polycarpa Fibrosa
''Polycarpa fibrosa'' is a species of tunicate in the family Styelidae. It is brown and globular and its outer surface is covered with a mat of fibrils. It normally lies buried in soft sediment on the seabed with only its two siphons protruding. It occurs in the Arctic Ocean and northern Atlantic Ocean. ''P. fibrosa'' was first identified and described by the American malacologist William Stimpson in 1852. Description ''Polycarpa fibrosa'' is globular or ovoid in shape and is about in diameter. It has a sac-like body with a tough covering known as a tunic, and is densely clad in short fibrils. There are two long, tapering, four-lobed siphons on the upper surface. Water is drawn into the body cavity through one of these, the buccal siphon, and expelled through the atrial siphon. The buccal siphon has a ring of up to 60 tentacles round the rim. These function to prevent particles that are too large from being drawn into the body cavity. This tunicate is a brownish colour and is wel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Stimpson
William Stimpson (February 14, 1832 – May 26, 1872) was a noted American scientist. He was interested particularly in marine biology. Stimpson became an important early contributor to the work of the Smithsonian Institution and later, director of the Chicago Academy of Sciences. Biography Stimpson was born in Boston, Massachusetts to Herbert Hathorne Stimpson and Mary Ann Devereau Brewer. The Stimpsons were of the colonial stock of Massachusetts, the earliest known member of the family being James Stimpson, who was married in 1661, in Milton. His mother died at an early age. William Stimpson's father was an ingenious inventor, and a leading merchant of Boston in the mid decades of the nineteenth century, trading as "H. & F. Stimpson, stoves and furnaces, corner of Congress and Water Streets. It was he who invented the "Stimpson range", the first sheet-iron cooking stove, famous in its day throughout New England. He also made improvements in rifles, and suggested the plac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bay Of Fundy
The Bay of Fundy (french: Baie de Fundy) is a bay between the Canadian provinces of New Brunswick and Nova Scotia, with a small portion touching the U.S. state of Maine. It is an arm of the Gulf of Maine. Its extremely high tidal range is the highest in the world. The name is likely a corruption of the French word , meaning 'split'. Hydrology Tides The tidal range in the Bay of Fundy is about ; the average tidal range worldwide is only . Some tides are higher than others, depending on the position of the moon, the sun, and atmospheric conditions. Tides are semidiurnal, meaning they have two highs and two lows each day, with about six hours and 13 minutes between each high and low tide. Because of tidal resonance in the funnel-shaped bay, the tides that flow through the channel are very powerful. In one 12-hour tidal cycle, about 100 billion tons (110 billion short tons) of water flows in and out of the bay, which is twice as much as the combined total flow of all th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metamorphosis
Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some insects, fish, amphibians, mollusks, crustaceans, cnidarians, echinoderms, and tunicates undergo metamorphosis, which is often accompanied by a change of nutrition source or behavior. Animals can be divided into species that undergo complete metamorphosis (" holometaboly"), incomplete metamorphosis (" hemimetaboly"), or no metamorphosis (" ametaboly"). Scientific usage of the term is technically precise, and it is not applied to general aspects of cell growth, including rapid growth spurts. Generally organisms with a larva stage undergo metamorphosis, and during metamorphosis the organism loses larval characteristics. References to "metamorphosis" in mammals are imprecise and only colloquial, but historically idealist ideas of transf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otocyst
Otic vesicle, or auditory vesicle, consists of either of the two sac-like invaginations formed and subsequently closed off during embryonic development. It is part of the neural ectoderm, which will develop into the membranous labyrinth of the inner ear. This labyrinth is a continuous epithelium, giving rise to the vestibular system and auditory components of the inner ear. During the earlier stages of embryogenesis, the otic placode invaginates to produce the otic cup. Thereafter, the otic cup closes off, creating the otic vesicle. Once formed, the otic vesicle will reside next to the neural tube medially, and on the lateral side will be paraxial mesoderm. Neural crest cells will migrate rostral and caudal to the placode. The general sequence in formation of the otic vesicle is relatively conserved across vertebrates, although there is much variation in timing and stages. Patterning during morphogenesis into the distinctive inner ear structures is determined by homeobox trans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tadpole
A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found in adult amphibians such as a lateral line, gills and swimming tails. As they undergo metamorphosis, they start to develop functional lungs for breathing air, and the diet of tadpoles changes drastically. A few amphibians, such as some members of the frog family Brevicipitidae, undergo direct development i.e., they do not undergo a free-living larval stage as tadpoles instead emerging from eggs as fully formed "froglet" miniatures of the adult morphology. Some other species hatch into tadpoles underneath the skin of the female adult or are kept in a pouch until after metamorphosis. Having no hard skeletons, it might be expected that tadpole fossils would not exist. However, traces of biofilms have been preserved and fossil tadpol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Notochord
In anatomy, the notochord is a flexible rod which is similar in structure to the stiffer cartilage. If a species has a notochord at any stage of its life cycle (along with 4 other features), it is, by definition, a chordate. The notochord consists of inner, vacuolated cells covered by fibrous and elastic sheaths, lies along the anteroposterior axis (''front to back''), is usually closer to the dorsal than the ventral surface of the embryo, and is composed of cells derived from the mesoderm. The most commonly cited functions of the notochord are: as a midline tissue that provides directional signals to surrounding tissue during development, as a skeletal (structural) element, and as a vertebral precursor. In lancelets the notochord persists throughout life as the main structural support of the body. In tunicates the notochord is present only in the larval stage, being completely absent in the adult animal. In these invertebrate chordates, the notochord is not vacuolated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Egg Incubation
Egg incubation is the process by which an egg, of oviparous (egg-laying) animals, develops an embryo within the egg, after the egg's formation and ovipositional release. Egg incubation is done under favorable environmental conditions, possibly by brooding and hatching the egg. Multiple and various factors are vital to the incubation of various species of animal. In many species of reptile for example, no fixed temperature is necessary, but the actual temperature determines the sex ratio of the offspring. In birds in contrast, the sex of offspring is genetically determined, but in many species a constant and particular temperature is necessary for successful incubation. Especially in poultry, the act of sitting on eggs to incubate them is called brooding. The action or behavioral tendency to sit on a clutch of eggs is also called broodiness, and most egg-laying breeds of poultry have had this behavior selectively bred out of them to increase production. Avian incubation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viviparous
Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the mother. The term 'viviparity' and its adjective form 'viviparous' derive from the Latin ''vivus'' meaning "living" and ''pario'' meaning "give birth to". Reproductive mode Five modes of reproduction have been differentiated in animals based on relations between zygote and parents. The five include two nonviviparous modes: ovuliparity, with external fertilisation, and oviparity, with internal fertilisation. In the latter, the female lays zygotes as eggs with a large yolk; this occurs in all birds, most reptiles, and some fishes. These modes are distinguished from viviparity, which covers all the modes that result in live birth: *Histotrophic viviparity: the zygotes develop in the female's oviducts, but find their nutrients by oopha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hermaphrodite
In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which either partner can act as the female or male. For example, the great majority of tunicates, pulmonate molluscs, opisthobranch, earthworms, and slugs are hermaphrodites. Hermaphroditism is also found in some fish species and to a lesser degree in other vertebrates. Most plants are also hermaphrodites. Animal species having different sexes, male and female, are called gonochoric, which is the opposite of hermaphrodite. There are also species where hermaphrodites exist alongside males (called androdioecy) or alongside females (called gynodioecy), or all three exist in the same species (called trioecy); these three ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molgula Oculata
''Molgula oculata'', commonly known as the sea grape, is a species of solitary tunicate in the family Molgulidae. It is native to the north eastern Atlantic Ocean and the North Sea. The specific name ''oculata'' means "having eyes"; the species has orifices which "seem like dark eyes within a spectacle-formed frame". Description ''Molgula oculata'' is nearly spherical in shape and is about in diameter. It has a sac-like body with a leathery covering known as its tunic, with two siphons on the upper surface. Water is drawn into the body cavity through a six-lobed oral siphon and expelled through a four-lobed atrial siphon. The oral siphon is surrounded by a ring of branched tentacles, the function of which is to prevent large particles being drawn into the pharynx with the water current. This tunicate is very well camouflaged. It is a sandy brown colour and is partially buried in the sediment on the seabed with the two siphons projecting. Sand grains and shell fragments adhere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molgula Occulta
''Molgula occulta'' is a species of solitary tunicate in the family Molgulidae. It is native to the north eastern Atlantic Ocean, the North Sea and the Mediterranean Sea. The specific name ''occulta'' means "tailless" and refers to the tunicate's larva, which lacks the tail found in some other species in the genus '' Molgula''. Description ''Molgula occulta'' is a solitary, oval-globular tunicate with a broad, shallow six-lobed oral siphon and a similar-sized four-lobed atrial siphon, both near the apex. It is tall, light brown in colour and resembles a kiwifruit in size and appearance. The rather stiff tunic wall is completely coated with shell fragments, mud particles and grains of sand. This distinguishes it from the otherwise very similar species '' Molgula oculata '' which has a bare patch around and between its siphons to which sediment does not adhere. Distribution and habitat ''Molgula occulta'' is found in the north eastern Atlantic and its range extends from Nor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gulf Of Maine
, image = , alt = , caption = , image_bathymetry = GulfofMaine2.jpg , alt_bathymetry = , caption_bathymetry = Major features of the Gulf of Maine , location = Northeast coast of the United States and southeast coast of Canada , group = , coordinates = , type = Gulf , etymology = , part_of = North Atlantic Ocean , inflow = , rivers = Saint John River, Penobscot River , outflow = , oceans = , catchment = , basin_countries = Canada and the United States , length = , width = , area = , depth = , max-depth = , volume = , residence_time = , salinity = , shore = , elevation = , temperature_high = , temperature_low = , frozen = , islands ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
