|
Paracatenula
''Paracatenula'' is a genus of millimeter sized free-living marine gutless catenulid flatworms. ''Paracatenula'' is found worldwide in warm temperate to tropical subtidal sediments. They are part of the interstitial meiofauna of sandy sediments. Adult ''Paracatenula'' lack a mouth and a gut and are associated with intracellular symbiotic alphaproteobacteria of the genus ''Candidatus''. Riegeria. The symbionts are housed in bacteriocytes in a specialized organ, the trophosome (Greek ‘food’). ''Ca.'' Riegeria can make up half of the worms' biomass. The beneficial symbiosis with the carbon dioxide fixing and sulfur-oxidizing endosymbionts allows the marine flatworm to live in nutrient poor environments. The symbionts ''not only'' provide the nutrition but also maintain the primary energy reserves in the symbiosis. Diversity Five species of ''Paracatenula'' have been described - ''P. erato'', ''P. kalliope'', ''P. polyhymnia'', ''P. urania'' and ''P. galateia'', named ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paracatenula Sediment OJ 2015
''Paracatenula'' is a genus of millimeter sized free-living marine gutless catenulid flatworms. ''Paracatenula'' is found worldwide in warm temperate to tropical subtidal sediments. They are part of the interstitial meiofauna of sandy sediments. Adult ''Paracatenula'' lack a mouth and a gut and are associated with intracellular symbiotic alphaproteobacteria of the genus ''Candidatus''. Riegeria. The symbionts are housed in bacteriocytes in a specialized organ, the trophosome (Greek ‘food’). ''Ca.'' Riegeria can make up half of the worms' biomass. The beneficial symbiosis with the carbon dioxide fixing and sulfur-oxidizing endosymbionts allows the marine flatworm to live in nutrient poor environments. The symbionts ''not only'' provide the nutrition but also maintain the primary energy reserves in the symbiosis. Diversity Five species of ''Paracatenula'' have been described - ''P. erato'', ''P. kalliope'', ''P. polyhymnia'', ''P. urania'' and ''P. galateia'', named ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catenulida
Catenulida is an order of flatworms in the classical classification, or a class of flatworms in a phylogenetic approach. They are relatively small free-living flatworms, inhabiting freshwater and marine environments. There are about 100 species described worldwide, but the simple anatomy makes species distinction problematic. Description The anatomy of catenulids is simple and lacks hard parts. The mouth is located anteriorly and connects to a simple pharynx and a simple intestine that forms a ciliated sac. They possess two pairs of nerve cords and often a statocyst, as well as a single protonephridium. The gonads are unpaired. Unusually, the male gonopore opens on the dorsal surface of the animal, above the pharynx, while the female reproductive system lacks any of the usual ducts and related structures found in other flatworms. The sperm is nonmobile and lacks flagella or cilia. Asexual reproduction by paratomy is common, and it usually leads to a chain of organisms (zooids), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retronectidae
Catenulida is an order of flatworms in the classical classification, or a class of flatworms in a phylogenetic approach. They are relatively small free-living flatworms, inhabiting freshwater and marine environments. There are about 100 species described worldwide, but the simple anatomy makes species distinction problematic. Description The anatomy of catenulids is simple and lacks hard parts. The mouth is located anteriorly and connects to a simple pharynx and a simple intestine that forms a ciliated sac. They possess two pairs of nerve cords and often a statocyst, as well as a single protonephridium. The gonads are unpaired. Unusually, the male gonopore opens on the dorsal surface of the animal, above the pharynx, while the female reproductive system lacks any of the usual ducts and related structures found in other flatworms. The sperm is nonmobile and lacks flagella or cilia. Asexual reproduction by paratomy is common, and it usually leads to a chain of organisms (zooids), h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platyhelminthes
The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek language, Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") are a Phylum (biology), phylum of relatively simple bilaterian, Segmentation (biology), unsegmented, soft-bodied invertebrates. Unlike other bilaterians, they are acoelomates (having no coelom, body cavity), and have no specialized circulatory system, circulatory and respiratory system, respiratory organ (anatomy), organs, which restricts them to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. The digestive cavity has only one opening for both ingestion (intake of nutrients) and egestion (removal of undigested wastes); as a result, the food cannot be processed continuously. In traditional medicinal texts, Platyhelminthes are divided into Turbellaria, which are mostly non-parasitic animals such as planarians, and three entirely p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flatworm
The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates. Unlike other bilaterians, they are acoelomates (having no body cavity), and have no specialized circulatory and respiratory organ (anatomy), organs, which restricts them to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. The digestive cavity has only one opening for both ingestion (intake of nutrients) and egestion (removal of undigested wastes); as a result, the food cannot be processed continuously. In traditional medicinal texts, Platyhelminthes are divided into Turbellaria, which are mostly non-parasitic animals such as planarians, and three entirely parasitic groups: Cestoda, Trematoda and Monogenea; however, since the turbellarians have since been prove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trophosome
A trophosome is a highly vascularised organ found in some animals that houses symbiotic bacteria that provide food for their host. Trophosomes are located in the coelomic cavity in the vestimentiferan tube worms (Siboglinidae, e.g. the giant tube worm ''Riftia pachyptila'') and in symbiotic flatworms of the genus ''Paracatenula''. Organization Initially, the trophosome in frenulates and vestimentiferans had been identified as a mesodermal tissue. The discovery of bacteria inside the trophosomal tissue only occurred in 1981 when the ultrastructure of trophosome of several frenulate species and of ''Sclerolinum brattstromi'' was studied. The bacteriocytes and symbionts composed of 70.5% and 24.1% of the trophosome's volume respectively. Generally, trophosome extends over the entire trunk region between the two longitudinal blood vessels from immediately posterior to the ventral ciliary band of the forepart to the posterior end of the trunk delineated by the septum between trunk and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal
Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motility, able to move, can Sexual reproduction, reproduce sexually, and go through an ontogenetic stage in which their body consists of a hollow sphere of Cell (biology), cells, the blastula, during Embryogenesis, embryonic development. Over 1.5 million Extant taxon, living animal species have been Species description, described—of which around 1 million are Insecta, insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from to . They have Ecology, complex interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology. Most living animal species are in Bilateria, a clade whose members have a Symmetry in biology#Bilate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autotroph
An autotroph or primary producer is an organism that produces complex organic compounds (such as carbohydrates, fats, and proteins) using carbon from simple substances such as carbon dioxide,Morris, J. et al. (2019). "Biology: How Life Works", 3rd edition, W. H. Freeman. generally using energy from light (photosynthesis) or inorganic chemical reactions (chemosynthesis). They convert an abiotic source of energy (e.g. light) into energy stored in organic compounds, which can be used by other organisms (e.g. heterotrophs). Autotrophs do not need a living source of carbon or energy and are the producers in a food chain, such as plants on land or algae in water (in contrast to heterotrophs as consumers of autotrophs or other heterotrophs). Autotrophs can reduce carbon dioxide to make organic compounds for biosynthesis and as stored chemical fuel. Most autotrophs use water as the reducing agent, but some can use other hydrogen compounds such as hydrogen sulfide. The primary produ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemotroph
A Chemotroph is an organism that obtains energy by the oxidation of electron donors in their environments. These molecules can be organic ( chemoorganotrophs) or inorganic (chemolithotrophs). The chemotroph designation is in contrast to phototrophs, which use photons. Chemotrophs can be either autotrophic or heterotrophic. Chemotrophs can be found in areas where electron donors are present in high concentration, for instance around hydrothermal vents. Chemoautotroph Chemoautotrophs, in addition to deriving energy from chemical reactions, synthesize all necessary organic compounds from carbon dioxide. Chemoautotrophs can use inorganic energy sources such as hydrogen sulfide, elemental sulfur, ferrous iron, molecular hydrogen, and ammonia or organic sources to produce energy. Most chemoautotrophs are extremophiles, bacteria or archaea that live in hostile environments (such as deep sea vents) and are the primary producers in such ecosystems. Chemoautotrophs generally fall into s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endosymbionts
An ''endosymbiont'' or ''endobiont'' is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship. (The term endosymbiosis is from the Greek: ἔνδον ''endon'' "within", σύν ''syn'' "together" and βίωσις ''biosis'' "living".) Examples are nitrogen-fixing bacteria (called rhizobia), which live in the root nodules of legumes, single-cell algae inside reef-building corals and bacterial endosymbionts that provide essential nutrients to insects. There are two types of symbiont transmissions. In horizontal transmission, each new generation acquires free living symbionts from the environment. An example is the nitrogen-fixing bacteria in certain plant roots. Vertical transmission takes place when the symbiont is transferred directly from parent to offspring. It is also possible for both to be involved in a mixed-mode transmission, where symbionts are transferred vertically for some generation before ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligotroph
An oligotroph is an organism that can live in an environment that offers very low levels of nutrients. They may be contrasted with copiotrophs, which prefer nutritionally rich environments. Oligotrophs are characterized by slow growth, low rates of metabolism, and generally low population density. Oligotrophic environments are those that offer little to sustain life. These environments include deep oceanic sediments, caves, glacial and polar ice, deep subsurface soil, aquifers, ocean waters, and leached soils. Examples of oligotrophic organisms are the cave-dwelling olm; the bacterium " ''Candidatus'' Pelagibacter communis", which is the most abundant organism in the oceans with an estimated 2 × 1028 individuals in total; and the lichens with their extremely low metabolic rate. Etymologically, the word "oligotroph" is a combination of the Greek adjective ''oligos'' (ὀλίγος) meaning "few" and the adjective ''trophikos'' (τροφικός)) meaning "feeding". Plant adaptatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nymphs
A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek; , ) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are typically tied to a specific place or landform, and are usually depicted as maidens. They were not necessarily immortal, but lived much longer than human beings. They are often divided into various broad subgroups, such as the Meliae (ash tree nymphs), the Dryads (oak tree nymphs), the Naiads (freshwater nymphs), the Nereids (sea nymphs), and the Oreads (mountain nymphs). Nymphs are often featured in classic works of art, literature, mythology, and fiction. Since the Middle Ages, nymphs have been sometimes popularly associated or even confused with fairies. Etymology The Greek word has the primary meaning of "young woman; bride, young wife" but is not usually associated with deities in particular. Yet the etymology of the noun remains u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
