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Xenoturbellid
''Xenoturbella'' is a genus of very simple bilaterians up to a few centimeters long. It contains a small number of marine benthic worm-like species. The first known species (''Xenoturbella bocki'') was discovered in 1915 by Sixten Bock, but it was only properly described in 1949 by Einar Westblad. Description ''Xenoturbella'' has a very simple body plan. It consists of dorsoventrally flattened acoelomate animals, with an anterior circumferential furrow. It shows two ciliated epithelial layers: an external epidermis and an internal gastrodermis lining the simple sac-like gut. The multiciliated epiderm displays unique interconnected ciliary rootlets and mode of withdrawal and resorption of worn epidermal cells. The mouth is a mid-ventral pore leading to a gastral cavity, and there is no anus: waste is dispelled through the same opening as food is taken in. The nervous system is composed by a net of interconnected neurons beneath the epidermis, without any concentration of neuron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bilateria
The Bilateria or bilaterians are animals with bilateral symmetry as an embryo, i.e. having a left and a right side that are mirror images of each other. This also means they have a head and a tail (anterior-posterior axis) as well as a belly and a back (ventral-dorsal axis). Nearly all are bilaterally symmetrical as adults as well; the most notable exception is the echinoderms, which achieve secondary pentaradial symmetry as adults, but are bilaterally symmetrical during embryonic development. Most animals are bilaterians, excluding sponges, ctenophores, placozoans and cnidarians. For the most part, bilateral embryos are triploblastic, having three germ layers: endoderm, mesoderm, and ectoderm. Except for a few phyla (i.e. flatworms and gnathostomulids), bilaterians have complete digestive tracts with a separate mouth and anus. Some bilaterians lack body cavities ( acoelomates, i.e. Platyhelminthes, Gastrotricha and Gnathostomulida), while others display primary body cavities (de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenoturbella Profunda
''Xenoturbella profunda'', the purple sock or sock worm, is a marine, benthic, deep-water worm-like species that belongs to the genus ''Xenoturbella''. It was discovered in eastern Pacific Ocean by a group of Californian and Australian scientists. The species was described in 2016 from seven specimens. ''X. profunda'' shares morphological similarities with other species of the genus ''Xenoturbella'', and is known for lacking respiratory, circulatory and an excretory system. Description The etymology of the species name refers to the fact that it lives deepest of the known xenoturbellids. ''Xenoturbella profunda'' individuals were sampled at ca. 3,700 m depth near a carbonate-hosted hydrothermal vent in the Gulf of California. This animal is in length, with a uniform pale pink colouration. The body wall displays several furrows: on the circumference, on the side, and two deep, longitudinal, dorsal ones. The longitudinal orientation involves a rounded anterior end, while ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenoturbella Monstrosa
''Xenoturbella monstrosa'', a deep-sea giant purple sock worm, is a marine, benthic, deep-water worm-like species that belongs to the genus ''Xenoturbella''. It was discovered in eastern Pacific Ocean by a group of Californian and Australian scientists. The species was described in 2016 from several specimens. ''Xenoturbella monstrosa'' shares morphological similarities with other species of the genus ''Xenoturbella'', and is known for lacking respiratory, circulatory and an excretory system. Description The etymology of the species name refers to its unusual large size among known xenoturbellids. ''Xenoturbella monstrosa'' is in length, with a purple or pale pink colouration. The body wall displays several furrows: on the circumference, on the side, and two deep, longitudinal, dorsal ones. The longitudinal orientation involves a rounded anterior end in front of the ring furrow, while the posterior end gradually reduces in thickness. The mouth is orientated ventrally, halfw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenoturbella Japonica
''Xenoturbella japonica'' is a marine benthic worm-like species that belongs to the genus ''Xenoturbella''. It has been discovered in western Pacific Ocean by a group of Japanese scientists from the University of Tsukuba. The species was described in 2017 in a study published in the journal BMC Evolutionary Biology, and amended in 2018. ''Xenotrubella japonica'' is known for lacking respiratory, circulatory and an excretory system. Description The etymology of the species name corresponds to the locality where the specimens were sampled. ''Xenoturbella japonica'' is in length, with a pale orange colouration. The body wall displays ring and side furrows. The mouth is orientated ventrally, just anterior to the ring furrow. The live specimen exhibits a conspicuous ventral epidermal glandular network. Tissues contain exogenous DNA corresponding to bivalve mollusks, the vesicomyid '' Acila castrensis'' and '' Nucula nucleus''. Phylogeny Comparison of mitochondrial DNA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Excretory System
The excretory system is a passive biological system that removes excess, unnecessary materials from the body fluids of an organism, so as to help maintain internal chemical homeostasis and prevent damage to the body. The dual function of excretory systems is the elimination of the waste products of metabolism and to drain the body of used up and broken down components in a liquid and gaseous state. In humans and other amniotes ( mammals, birds and reptiles) most of these substances leave the body as urine and to some degree exhalation, mammals also expel them through sweating. Only the organs specifically used for the excretion are considered a part of the excretory system. In the narrow sense, the term refers to the urinary system. However, as excretion involves several functions that are only superficially related, it is not usually used in more formal classifications of anatomy or function. As most healthy functioning organs produce metabolic and other wastes, the entire or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenoturbella Hollandorum
''Xenoturbella hollandorum'' is a marine, benthic worm-like species that belongs to the genus ''Xenoturbella''. It was discovered in eastern Pacific Ocean by a group of Californian and Australian scientists. The species was described in 2016. ''X. hollandorum'' shares morphological similarities with other species of the genus ''Xenoturbella'', and is known for lacking respiratory, circulatory and an excretory system. Description The etymology of the species name corresponds to a scientific patronym in honor of Linda and Nicholas Holland. ''Xenoturbella hollandorum'' is in length, with a uniform bright pink colouration. The body wall displays several furrows: on the circumference, on the side, and two deep, longitudinal, dorsal ones. The mouth is orientated ventrally, anterior to the ring furrow. The live specimen exhibits an inconspicuous epidermal ventral glandular network. Phylogeny Comparison of mitochondrial DNA Mitochondrial DNA (mtDNA or mDNA) is the DNA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenoturbella Churro
''Xenoturbella churro'' is a marine, benthic, deep-water worm-like species that belongs to the genus ''Xenoturbella''. It was discovered in eastern Pacific Ocean by a group of Californian and Australian scientists. The species was described in 2016 from a single specimen. ''X. churro'' shares morphological similarities with other species of the genus ''Xenoturbella'', and is known for lacking respiratory, circulatory and an excretory system. Description The etymology of the species name refers to the resemblance with churro, a fried-dough pastry. This animal is in length, with a uniform orange/pink colouration. The body wall displays several furrows: on the circumference, on the side, and four deep, longitudinal, dorsal ones. The longitudinal orientation involves a rounded anterior end, while the posterior end sharply reduces in thickness. The mouth is orientated ventrally, halfway between the anterior end and the ring furrow. The live specimen exhibited an epidermal ventra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turbellarian
The Turbellaria are one of the traditional sub-divisions of the phylum Platyhelminthes (flatworms), and include all the sub-groups that are not exclusively parasitic. There are about 4,500 species, which range from to large freshwater forms more than long or terrestrial species like ''Bipalium kewense'' which can reach in length. All the larger forms are flat with ribbon-like or leaf-like shapes, since their lack of respiratory and circulatory systems means that they have to rely on diffusion for internal transport of metabolites. However, many of the smaller forms are round in cross section. Most are predators, and all live in water or in moist terrestrial environments. Most forms reproduce sexually and with few exceptions all are simultaneous hermaphrodites. The Acoelomorpha and the genus ''Xenoturbella'' were formerly included in the Turbellaria, but are no longer regarded as Platyhelminthes. All the exclusively parasitic Platyhelminthes form a monophyletic group Neodermat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the Roman Republic it became the dominant language in the Italian region and subsequently throughout the Roman Empire. Even after the fall of Western Rome, Latin remained the common language of international communication, science, scholarship and academia in Europe until well into the 18th century, when other regional vernaculars (including its own descendants, the Romance languages) supplanted it in common academic and political usage, and it eventually became a dead language in the modern linguistic definition. Latin is a highly inflected language, with three distinct genders (masculine, feminine, and neuter), six or seven noun cases (nominative, accusative, genitive, dative, ablative, and vocative), five declensions, four verb conjuga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic period (), and the Classical period (). Ancient Greek was the language of Homer and of fifth-century Athenian historians, playwrights, and philosophers. It has contributed many words to English vocabulary and has been a standard subject of study in educational institutions of the Western world since the Renaissance. This article primarily contains information about the Epic and Classical periods of the language. From the Hellenistic period (), Ancient Greek was followed by Koine Greek, which is regarded as a separate historical stage, although its earliest form closely resembles Attic Greek and its latest form approaches Medieval Greek. There were several regional dialects of Ancient Greek, of which Attic Greek developed into Koine. Dia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neochildia Fusca
''Neochildia'' is a monotypic genus of a dark brown acoel belonging to the family Convolutidae. The only species is ''Neochildia fusca''. The nervous system is composed of an anterior compact brain organized as a layer of neural somata surrounding a central neuropil Neuropil (or "neuropile") is any area in the nervous system composed of mostly unmyelinated axons, dendrites and glial cell processes that forms a synaptically dense region containing a relatively low number of cell bodies. The most prevalent anat ... free of cell bodies. References Acoelomorphs {{Xenacoelomorpha-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embryo
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm cell. The resulting fusion of these two cells produces a single-celled zygote that undergoes many cell divisions that produce cells known as blastomeres. The blastomeres are arranged as a solid ball that when reaching a certain size, called a morula, takes in fluid to create a cavity called a blastocoel. The structure is then termed a blastula, or a blastocyst in mammals. The mammalian blastocyst hatches before implantating into the endometrial lining of the womb. Once implanted the embryo will continue its development through the next stages of gastrulation, neurulation, and organogenesis. Gastrulation is the formation of the three germ layers that will form all of the different parts of the body. Neurulation forms the nervous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
