|
Asexual Reproduction In Starfish
Asexual reproduction in starfish takes place by fission or through autotomy of arms. In fission, the central disc breaks into two pieces and each portion then regenerates the missing parts. In autotomy, an arm is shed with part of the central disc attached, which continues to live independently as a "comet", eventually growing a new set of arms. Although almost all sea stars can regenerate their limbs, only a select few sea star species are able to reproduce in these ways. Fission Fissiparity in the starfish family Asteriidae is confined to the genera '' Coscinasterias'', '' Stephanasterias'' and '' Sclerasterias''. Another family in which asexual reproduction by fission has independently arisen is the Asterinidae. The life span is at least four years. A dense population of '' Stephanasterias albula'' was studied at North Lubec, Maine. All the individuals were fairly small, with arm lengths not exceeding , but no juveniles were found, suggesting that there had been no recent lar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asexual Reproduction
Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the full set of genes of their single parent and thus the newly created individual is genetically and physically similar to the parent or an exact clone of the parent. Asexual reproduction is the primary form of reproduction for single-celled organisms such as archaea and bacteria. Many eukaryotic organisms including plants, animals, and fungi can also reproduce asexually. In vertebrates, the most common form of asexual reproduction is parthenogenesis, which is typically used as an alternative to sexual reproduction in times when reproductive opportunities are limited. Komodo dragons and some monitor lizards can also reproduce asexually. While all prokaryotes reproduce without the formation and fusion of gametes, mechanisms for lateral gene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tube Feet
Tube feet (technically podia) are small active tubular projections on the oral face of an echinoderm, whether the arms of a starfish, or the undersides of sea urchins, sand dollars and sea cucumbers; they are more discreet though present on brittle stars, and have only a feeding function in feather stars. They are part of the water vascular system. Structure and function Tube feet function in locomotion, feeding, and respiration. The tube feet in a starfish are arranged in grooves along the arms. They operate through hydraulic pressure. They are used to pass food to the oral mouth at the center, and can attach to surfaces. A starfish that is inverted turns one arm over and attaches it to a solid surface, and levers itself the right way up. Tube feet allow these different types of animals to stick to the ocean floor and move slowly. Each tube foot consists of two parts: the ampulla and the podium. The ampulla is a water-filled sac contained in the body of the animal that co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Vascular System
The water vascular system is a hydraulic system used by echinoderms, such as sea stars and sea urchins, for locomotion, food and waste transportation, and respiration. The system is composed of canals connecting numerous tube feet. Echinoderms move by alternately contracting muscles that force water into the tube feet, causing them to extend and push against the ground, then relaxing to allow the feet to retract. The exact structure of the system varies somewhat between the five classes of echinoderm. The system is part of the coelomic cavities of echinoderms, together with the haemal coelom (or haemal system), perivisceral coelom, gonadal coelom and perihaemal coelom. Other terms sometimes used to refer to the water vascular system are "ambulacral system" and "aquiferous system". In the past, "aquiferous system" was also used to refer to many unrelated invertebrate structures, but today, it is restricted to water channels in sponges and the hydrostatic skeleton of some mollu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linckia Multifora
''Linckia multifora'' is a variously colored starfish in the Family (biology), family Ophidiasteridae that is found in the Indian Ocean and Red Sea. Its common names include the Dalmatian Linckia, mottled Linckia, spotted Linckia, multicolor sea star and multi-pore sea star.Seeing stars: ''Linckia multifora'' The Right Blue. Retrieved 2011-09-24. Description ''Linckia multifora'' has a small disk and five long, slim cylindrical arms that taper slightly towards the tips. The colour is variable and includes brown, pink, red, or gray with small red spots. The surface has a rough texture and is covered in granulations. This starfish can grow to a diameter of 2 to 5 inches (5 to 13 cm).Distribution ''Linckia multifora'' is circumtropical. It i ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linckia Columbiae
''Linckia columbiae'' is a species of starfish in the family Ophidiasteridae. It is found in the East Pacific where it ranges from California (USA) to northwest Peru, including offshore islands such as the Galápagos.James, M.J., eds. (1991). ''Galápagos Marine Invertebrates: Taxonomy, Biogeography, and Evolution in Darwin's Islands.'' pp. 349. Topics in Geobiology. Common names include fragile star, Pacific comet sea star and variable sea star. Description ''Linckia columbiae'' can grow to 10 cm (4 in) across and varies greatly in colour and shape and even the number of rays. Writing in 1904, Monks stated, "In over 400 specimens examined not more than four were symmetrical, and no two were alike ... The normal number of rays is five, but some specimens have only one, while others have four, six, seven or even nine." The disc is small with one or two madreporites, usually oval and variable in size. The long cylindrical rays have blunt, triangular points that turn up s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linckia Guildingi
''Linckia guildingi'', also called the common comet star, Guilding's sea star or the green Linckia, is a species of sea star reported from the shallow waters of the tropical Pacific Ocean, Indian Ocean, Atlantic Ocean and the Caribbean Sea. Taxonomy Recent studies have indicated that ''Linckia guildingi'' may represent several cryptic species. Examination of the mtDNA showed that there are two clades within ''L. guildingi''. The divergence between these implies that they separated over a million years ago. Distribution This species was described from St Vincent's, ( Saint Vincent (Antilles)) in the Caribbean Sea. Description ''L. guildingi'' has a small disc and usually 5 (occasionally 4 or 6) long cylindrical arms. The upper surface appears smooth but is in fact rough to the touch with low, firm nodules. Though this starfish is often green, it comes in a range of colours including various shades of brown, blue and dull red. Biology ''L. guildingi'' sometimes exhibits autotomy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Samoa
Samoa, officially the Independent State of Samoa; sm, Sāmoa, and until 1997 known as Western Samoa, is a Polynesian island country consisting of two main islands ( Savai'i and Upolu); two smaller, inhabited islands ( Manono and Apolima); and several smaller, uninhabited islands, including the Aleipata Islands ( Nu'utele, Nu'ulua, Fanuatapu and Namua). Samoa is located west of American Samoa, northeast of Tonga (closest foreign country), northeast of Fiji, east of Wallis and Futuna, southeast of Tuvalu, south of Tokelau, southwest of Hawaii, and northwest of Niue. The capital city is Apia. The Lapita people discovered and settled the Samoan Islands around 3,500 years ago. They developed a Samoan language and Samoan cultural identity. Samoa is a unitary parliamentary democracy with 11 administrative divisions. It is a sovereign state and a member of the Commonwealth of Nations. Western Samoa was admitted to the United Nations on 15 December 1976. Becaus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apia
Apia () is the capital and largest city of Samoa, as well as the nation's only city. It is located on the central north coast of Upolu, Samoa's second-largest island. Apia falls within the political district (''itūmālō'') of Tuamasaga. The Apia Urban Area (generally known as the City of Apia) has a population of 37,391 (2016 census). Its geographic boundaries extend roughly from Letogo village to the newer, industrialized region of Apia known as "Vaitele". History Apia was originally a small village (the 1800 population was 304), from which the country's capital took its name. Apia Village still exists within the larger modern capital of Apia, which has grown into a sprawling urban area that encompasses many villages. Like every other settlement in the country, Apia Village has its own ''matai'' (leaders) and ''fa'alupega'' (genealogy and customary greetings) according to fa'a Samoa. The modern city of Apia was founded in the 1850s, and it has been the official capi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linckia
''Linckia'' is a genus of sea stars found mainly in the Indo-Pacific region. They are known to be creatures with remarkable regenerative abilities, and capable of defensive autotomy against predators. They reproduce asexually. The genus is named after the German naturalist Johann Heinrich Linck (1674–1734). Systematics Five groups within ''Linckia'' have been clearly genetically differentiated - ''L. columbiae'', ''L. bouvieri'', two clades within ''L. guildingi'', and one clade with two subclades consisting of both ''L. laevigata'' and ''L. multifora'' .Williams, S.T., Species boundaries in the starfish genus Linckia. Marine Biology, Vol 136, No 1, p.137-148 (2000) A list of species of ''Linckia'': *'' Linckia bouvieri'' Perrier, 1875 (=''Linckia formosa'') *''Linckia columbiae'' Gray, 1840 (=''Ophidiaster colombiae'', ''Phataria fascialis'') * '' Linckia gracilis'' Liao, 1985 *''Linckia guildingi'' Gray, 1840 (=''Linckia diplax'', ''Linckia ehrenbergii'') * '' Linckia kuhl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ernst Haeckel
Ernst Heinrich Philipp August Haeckel (; 16 February 1834 – 9 August 1919) was a German zoologist, naturalist, eugenicist, philosopher, physician, professor, marine biologist and artist. He discovered, described and named thousands of new species, mapped a genealogical tree relating all life forms and coined many terms in biology, including ''ecology'', '' phylum'', ''phylogeny'', and ''Protista.'' Haeckel promoted and popularised Charles Darwin's work in Germany and developed the influential but no longer widely held recapitulation theory ("ontogeny recapitulates phylogeny") claiming that an individual organism's biological development, or ontogeny, parallels and summarises its species' evolutionary development, or phylogeny. The published artwork of Haeckel includes over 100 detailed, multi-colour illustrations of animals and sea creatures, collected in his ''Kunstformen der Natur'' ("Art Forms of Nature"), a book which would go on to influence the Art Nouveau artistic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
