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Nemertea
Nemertea is a phylum of animals also known as ribbon worms or proboscis worms, consisting of about 1300 known species. Most ribbon worms are very slim, usually only a few millimeters wide, although a few have relatively short but wide bodies. Many have patterns of yellow, orange, red and green coloration. The foregut, stomach and intestine run a little below the midline of the body, the anus is at the tip of the tail, and the mouth is under the front. A little above the gut is the , a cavity which mostly runs above the midline and ends a little short of the rear of the body. All species have a proboscis which lies in the rhynchocoel when inactive but wikt:eversion, everts to emerge just above the mouth to capture the animal's prey with venom. A highly extensible muscle in the back of the rhynchocoel pulls the proboscis in when an attack ends. A few species with stubby bodies Filter feeders, filter feed and have suckers at the front and back ends, with which they attach to a Hos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enopla
Enopla is one of the classes of the worm phylum Nemertea, characterized by the presence of a peculiar armature of spines or plates in the proboscis. Evolution and systematics The record of nemerteans is extremely sparse, as would be expected from a soft-bodied animal. The Cambrian fossil, '' Amiskwia'', has been interpreted as a nemertean based on its resemblance to some pelagic ribbon worms; however, this interpretation is disputed by many paleontologists. The enoplan nemerteans have been regarded as highly derived based on a more complicated muscle arrangement in the body wall and a more complex nervous system. However, whether this is a plesiomorphic or apomorphic character is not clear, and recent molecular studies are inconclusive in this respect. Class Enopla used to be divided in two subclasses, Hoplonemertea and Bdellonemertea, but recent phylogenetic analyses based on nucleotide sequences show that Bdellonemertea should be included in Hoplonemertea. Hoplonemerte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pilidiophora
Heteronemertea is a monophyletic order of about 500 species of nemertean worms. It contains genera such as '' Lineus'' and '' Cerebratulus'', and includes the largest and most muscular nemerteans. Almost all heteronemerteans have three primary body-wall muscle strata: an outer longitudinal, a middle circular, and an inner longitudinal. The lateral nerve cords are outside the circular muscle, as in palaeonemerteans, but separated from the epidermis The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and Subcutaneous tissue, hypodermis. The epidermal layer provides a barrier to infection from environmental pathogens and regulates the ... by the usually well-developed outer longitudinal muscle. Taxonomy Families within the order Heteronemertea include: * Baseodiscidae * Cerebratulidae * Gorgonorhynchidae * Lineidae * Mixolineidae * Panorhynchidae * Poliopsiidae * Polybrachiorhynchidae * Pussylineidae * Riseriellidae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palaeonemertea
Palaeonemertea is a class of primitive nemertean worm. It may be para- or polyphyletic, consisting of three to five clades and totalling about 100 species. These worms have several apparently simple features and, as their name suggests, they are often considered to be the most primitive nemertea Nemertea is a phylum of animals also known as ribbon worms or proboscis worms, consisting of about 1300 known species. Most ribbon worms are very slim, usually only a few millimeters wide, although a few have relatively short but wide bodies. ...ns. The primary body-wall musculature consists of an outer circular layer overlying a longitudinal layer. The group includes genera such as '' Cephalothrix'' in which the nerve cords are inside the body-wall longitudinal muscle, and '' Tubulanus'', in which the nerve cords are between the outer circular muscle and the epidermis. Tubulanids are commonly encountered in rocky areas of intertidal zones in the northern hemisphere. They are oft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hoplonemertea
Hoplonemertea is a class of ribbon worms. It contains two orders: * Monostilifera * Polystilifera The proboscis is armed with one or more stylets; intestine straight, mostly with paired lateral diverticula In medicine or biology, a diverticulum is an outpouching of a hollow (or a fluid-filled) structure in the body. Depending upon which layers of the structure are involved, diverticula are described as being either true or false. In medicine, t ...; no posterior ventral sucker. References Spiralian classes {{nemertean-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annelid
The annelids (), also known as the segmented worms, are animals that comprise the phylum Annelida (; ). The phylum contains over 22,000 extant species, including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecologies – some in marine environments as distinct as tidal zones and hydrothermal vents, others in fresh water, and yet others in moist terrestrial environments. The annelids are bilaterally symmetrical, triploblastic, coelomate, invertebrate organisms. They also have parapodia for locomotion. Most textbooks still use the traditional division into polychaetes (almost all marine), oligochaetes (which include earthworms) and leech-like species. Cladistic research since 1997 has radically changed this scheme, viewing leeches as a sub-group of oligochaetes and oligochaetes as a sub-group of polychaetes. In addition, the Pogonophora, Echiura and Sipuncula, previously regarded as separate phyla, are now regarded as sub-grou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flame Cell
A flame cell is a specialized excretory cell found in simple invertebrates, including flatworms ( Platyhelminthes), rotifers and nemerteans; these are the simplest animals to have a dedicated excretory system. Flame cells function like a kidney, removing waste materials. Bundles of flame cells are called protonephridia. The flame cell has a nucleated cell body, with a "cup-shaped" projection, with flagella covering the inner surface of the cup. The beating of these flagella resemble a flame, giving the cell its name. The cup is attached to a tube cell, whose inner surface is also coated in cilia, which help to move liquid through the tube cell. The tube opens externally through a ''nephropore'', or, in the trematoda, into an excretory bladder. The function of these cells is to regulate the osmotic pressure of the worm, and maintain its ionic balance. Microvilli in the tube cell may be used to reabsorb some ions. Molecules enter the tubule in tube cells through the gap betw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nematoda
The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitism, parasitic. Parasitic worms (helminths) are the cause of Soil-transmitted helminthiasis, soil-transmitted helminthiases. They are classified along with arthropods, tardigrades and other moulting animalia, animals in the clade Ecdysozoa. Unlike the flatworms, nematodes have a tubular digestion, digestive system, with openings at both ends. Like tardigrades, they have a reduced number of Hox genes, but their sister phylum Nematomorpha has kept the ancestral protostome Hox genotype, which shows that the reduction has occurred within the nematode phylum. Nematode species can be difficult to distinguish from one another. Consequently, estimates of the number of nematode species are uncertain. A 2013 survey of animal biodiversity suggested there are over 25,000. Es ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cilia
The cilium (: cilia; ; in Medieval Latin and in anatomy, ''cilium'') is a short hair-like membrane protrusion from many types of eukaryotic cell. (Cilia are absent in bacteria and archaea.) The cilium has the shape of a slender threadlike projection that extends from the surface of the much larger cell body. Eukaryotic flagella found on sperm cells and many protozoans have a similar structure to motile cilia that enables swimming through liquids; they are longer than cilia and have a different undulating motion. There are two major classes of cilia: ''motile'' and ''non-motile'' cilia, each with two subtypes, giving four types in all. A cell will typically have one primary cilium or many motile cilia. The structure of the cilium core, called the axoneme, determines the cilium class. Most motile cilia have a central pair of single microtubules surrounded by nine pairs of double microtubules called a 9+2 axoneme. Most non-motile cilia have a 9+0 axoneme that lacks the central pai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mucus
Mucus (, ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both Serous fluid, serous and mucous cells. It is a viscous colloid containing inorganic ions, inorganic salts, antimicrobial enzymes (such as lysozymes), Antibody, immunoglobulins (especially Immunoglobulin A, IgA), and glycoproteins such as lactoferrin and mucins, which are produced by goblet cells in the mucous membranes and submucosal glands. Mucus covers the Epithelium, epithelial cells that interact with outside environment, serves to protect the linings of the respiratory system, respiratory, Digestion#Digestive system, digestive, and Genitourinary system, urogenital systems, and structures in the Visual system, visual and auditory systems from pathogenic Fungus, fungi, bacteria and viruses. Most of the mucus in the body is produced in the gastrointestinal tract. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anatomical Terms Of Location
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of anatomical planes and axes. The meaning of terms that are used can change depending on whether a vertebrate is a biped or a quadruped, due to the difference in the neuraxis, or if an invertebrate is a non-bilaterian. A non-bilaterian has no anterior or posterior surface for example but can still have a descriptor used such as proximal or distal in relation to a body part that is nearest to, or furthest from its middle. International organisations have determined vocabularies that are often used as standards for subdisciplines of anatomy. For example, '' Termi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crustacean
Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthropods including decapods (shrimps, prawns, crabs, lobsters and crayfish), seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, opossum shrimps, amphipods and mantis shrimp. The crustacean group can be treated as a subphylum under the clade Mandibulata. It is now well accepted that the hexapods (insects and entognathans) emerged deep in the Crustacean group, with the completed pan-group referred to as Pancrustacea. The three classes Cephalocarida, Branchiopoda and Remipedia are more closely related to the hexapods than they are to any of the other crustaceans ( oligostracans and multicrustaceans). The 67,000 described species range in size from '' Stygotantulus stocki'' at , to the Japanese ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carnivores
A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose nutrition and energy requirements are met by consumption of animal tissues (mainly muscle, fat and other soft tissues) as food, whether through predation or scavenging. Nomenclature Mammal order The technical term for mammals in the order Carnivora is ''carnivoran'', and they are so-named because most member species in the group have a carnivorous diet, but the similarity of the name of the order and the name of the diet causes confusion. Many but not all carnivorans are meat eaters; a few, such as the large and small cats (Felidae) are ''obligate'' carnivores (see below). Other classes of carnivore are highly variable. The ursids (bears), for example: while the Arctic polar bear eats meat almost exclusively (more than 90% of its diet is meat), almost all other bear species are omnivorous, and one species, the giant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
