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Ophidiaster Granifer
''Ophidiaster granifer'', the grained seastar, is a species of starfish in the family Ophidiasteridae. It is found in the Red Sea and the Indo-Pacific and is the only known species of starfish to reproduce by parthenogenesis. Description ''Ophidiaster granifer'' is a small five armed starfish with a cryptic mottled brown colouration. It has a rough, granular appearance and grows to a diameter of about . The disc is quite small and the medium-length, fairly broad arms have rounded tips. Biology No male ''Ophidiaster granifer'' has ever been identified and all known adults are female. As far as is known, ''Ophidiaster granifer'' is the only member of the phylum Echinodermata to reproduce exclusively by parthenogenesis. In this species, eggs are liberated into the sea in a synchronous spawning event but no fertilisation takes place. The eggs are large, with a diameter of and the mother attaches some of them to the underside of boulders. Here they develop until they undergo metam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Christian Frederik Lütken
Christian Frederik Lütken (; 7 October 1827, in Sorø – 6 February 1901), was a Denmark, Danish zoologist and naturalist. In 1852, he resigned his commission as a lieutenant with the Danish army, and earned his master's degree in sciences the following year.Darwinarkivet.dk Christian Frederik Lütken (1827-1901) Afterwards, he served as an assistant to Japetus Steenstrup (1813–1897) at the University of Copenhagen Zoological Museum, at the time an independent institution, now part of the University of Copenhagen Botanical Garden, Natural History Museum of Denmark. Following Steenstrup's retirement in 1885, he became a professor of zoology and director of the zoological museum. As he grew older, he suffered from physical infirmities and during the last year of his life, he was strick ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. However, only about 14% of these had been described by 2011. All species (except viruses) are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature, also sometimes i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Starfish
Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish are also known as asteroids due to being in the class Asteroidea. About 1,900 species of starfish live on the seabed in all the world's oceans, from warm, tropical zones to frigid, polar regions. They are found from the intertidal zone down to abyssal depths, at below the surface. Starfish are marine invertebrates. They typically have a central disc and usually five arms, though some species have a larger number of arms. The aboral or upper surface may be smooth, granular or spiny, and is covered with overlapping plates. Many species are brightly coloured in various shades of red or orange, while others are blue, grey or brown. Starfish have tube feet operated by a hydraulic system and a mouth at the centre of the oral or lower surface. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Family (biology)
Family ( la, familia, plural ') is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks between the ranks of family and genus. The official family names are Latin in origin; however, popular names are often used: for example, walnut trees and hickory trees belong to the family Juglandaceae, but that family is commonly referred to as the "walnut family". What belongs to a family—or if a described family should be recognized at all—are proposed and determined by practicing taxonomists. There are no hard rules for describing or recognizing a family, but in plants, they can be characterized on the basis of both vegetative and reproductive features of plant species. Taxonomists often take different positions about descriptions, and there may be no broad consensus across the scientific community for some time. The publishing of new data and opini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophidiasteridae
The Ophidiasteridae (Greek ''ophidia'', Οφιδια, "of snakes", diminutive form) are a family of sea stars with about 30 genera. Occurring both in the Indo-Pacific and Atlantic Oceans, ophidiasterids are greatest in diversity in the Indo-Pacific. Many of the genera in this family exhibit brilliant colors and patterns, which sometimes can be attributed to aposematism and crypsis to protect themselves from predators. Some ophidiasterids possess remarkable powers of regeneration, enabling them to either reproduce asexually or to survive serious damage made by predators or forces of nature (an example for this is the genus ''Linckia''). Some species belonging to ''Linckia'', ''Ophidiaster'' See last paragraph in review above Analysis and ''Phataria'' shed single arms that regenerate the disc and the remaining rays to form a complete individual. Some of these also reproduce asexually by parthenogenesis. The name of the family is taken from the genus ''Ophidiaster'', whose limbs are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parthenogenesis
Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and development of embryos occur in a gamete (egg or sperm) without combining with another gamete (e.g., egg and sperm fusing). In animals, parthenogenesis means development of an embryo from an unfertilized Gametophyte, egg cell. In plants, parthenogenesis is a component process of apomixis. In algae, parthenogenesis can mean the development of an embryo from either an individual sperm or an individual egg. Parthenogenesis occurs naturally in some plants, algae, invertebrate animal species (including nematodes, some tardigrades, water fleas, some scorpions, aphids, some mites, some bees, some Phasmatodea and parasitic wasps) and a few vertebrates (such as some fish, amphibians, reptiles and birds). This type of reproduction has been induced artificially ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crypsis
In ecology, crypsis is the ability of an animal or a plant to avoid observation or detection by other animals. It may be a predation strategy or an antipredator adaptation. Methods include camouflage, nocturnality, subterranean lifestyle and mimicry. Crypsis can involve visual, olfactory (with pheromones) or auditory concealment. When it is visual, the term cryptic coloration, effectively a synonym for animal camouflage, is sometimes used, but many different methods of camouflage are employed by animals or plants. Overview There is a strong evolutionary pressure for animals to blend into their environment or conceal their shape, for prey animals to avoid predators and for predators to be able to avoid detection by prey. Exceptions include large herbivores without natural enemies, brilliantly colored birds that rely on flight to escape predators, and venomous or otherwise powerfully armed animals with warning coloration. Cryptic animals include the tawny frogmouth (feather pat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylum
In biology, a phylum (; plural: phyla) is a level of classification or taxonomic rank below kingdom and above class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclature for algae, fungi, and plants accepts the terms as equivalent. Depending on definitions, the animal kingdom Animalia contains about 31 phyla, the plant kingdom Plantae contains about 14 phyla, and the fungus kingdom Fungi contains about 8 phyla. Current research in phylogenetics is uncovering the relationships between phyla, which are contained in larger clades, like Ecdysozoa and Embryophyta. General description The term phylum was coined in 1866 by Ernst Haeckel from the Greek (, "race, stock"), related to (, "tribe, clan"). Haeckel noted that species constantly evolved into new species that seemed to retain few consistent features among themselves and therefore few features that distinguished them as a group ("a self-contained unity" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echinodermata
An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 7,000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are the largest entirely marine phylum. The first definitive echinoderms appeared near the start of the Cambrian. The echinoderms are important both ecologically and geologically. Ecologically, there are few other groupings so abundant in the biotic desert of the deep sea, as well as shallower oceans. Most echinoderms are able to reproduce asexually and regenerate tissue, organs, and limbs; in some cases, they can undergo complete regeneration from a single limb. Geolo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Egg (biology)
An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the animal hatches. Most arthropods such as insects, vertebrates (excluding live-bearing mammals), and mollusks lay eggs, although some, such as scorpions, do not. Reptile eggs, bird eggs, and monotreme eggs are laid out of water and are surrounded by a protective shell, either flexible or inflexible. Eggs laid on land or in nests are usually kept within a warm and favorable temperature range while the embryo grows. When the embryo is adequately developed it hatches, i.e., breaks out of the egg's shell. Some embryos have a temporary egg tooth they use to crack, pip, or break the eggshell or covering. The largest recorded egg is from a whale shark and was in size. Whale shark eggs typically hatch within the mother. At and up to , the o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synchronous Spawning
''Reproductive synchrony'' is a term used in evolutionary biology and behavioral ecology. Reproductive synchrony—sometimes termed "ovulatory synchrony"—may manifest itself as "breeding seasonality". Where females undergo regular menstruation, " menstrual synchrony" is another possible term. Reproduction is said to be synchronised when fertile matings across a population are temporarily clustered, resulting in multiple conceptions (and consequent births) within a restricted time window. In marine and other aquatic contexts, the phenomenon may be referred to as mass spawning. Mass spawning has been observed and recorded in a large number of phyla, including in coral communities within the Great Barrier Reef. In primates, reproductive synchrony usually takes the form of conception and birth seasonality. The regulatory "clock", in this case, is the sun's position in relation to the tilt of the earth. In nocturnal or partly nocturnal primates—for example, owl monkeys—the per ... [...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 transformation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
