instance_of atelocerata
In zoological ___MASK58___ , a subphylum is a ___MASK10___ below the rank of phylum . A myriad ( from Ancient Greek , " myrias ") is technically the ___MASK27___ ___MASK86___ thousand ; in that sense , the term is used almost exclusively in translations from Greek , Latin , or ___MASK28___ , or when talking about ancient Greek numbers . More generally , a myriad may be an indefinitely large ___MASK27___ of things . Myriapoda is a subphylum of arthropods containing millipedes , centipedes , and others . The ___MASK33___ contains over 13 , 000 ___MASK85___ , most of which are terrestrial . Although their name suggests they have myriad ( 10 , 000 ) legs , myriapods range from having over 750 legs ( the millipede " Illacme plenipes ") to having fewer than ___MASK86___ legs . Millipedes are a ___MASK33___ of arthropods that are characterised by having ___MASK12___ pairs of jointed legs on most body segments ; they are known scientifically as the class Diplopoda , the name being derived from this ___MASK4___ . Each double - legged segment is a result of ___MASK12___ ___MASK60___ segments fused together . Most millipedes have very elongated cylindrical or flattened bodies with more than 20 segments , while pill millipedes are shorter and can roll into a ball . Although the name " millipede " derives from the Latin for " thousand feet ", no known species has 1 , 000 ; the record of 750 legs belongs to " Illacme plenipes ". There are approximately 12 , 000 named species classified into 16 orders and around 140 families , making Diplopoda the largest class of myriapods , an arthropod ___MASK33___ which also includes centipedes and other multi - legged creatures . Arachnids are a ___MASK95___ ( Arachnida ) of ___MASK8___ - legged invertebrate animals ( arthropods ), in the subphylum Chelicerata . All arachnids have ___MASK23___ legs , although the ___MASK96___ pair of legs in some species has converted to a sensory function , while in other species , different appendages can grow large enough to take on the appearance of extra pairs of legs . The term is derived from the Greek word (" aráchn "), meaning " spider ". Spiders are the largest order in the ___MASK95___ . ___MASK5___ is a standard protocol for allowing serial ___MASK44___ for telecommunications programs under the ___MASK72___ ___MASK80___ . ___MASK5___ is an acronym for " Fido Opus SEAdog Standard Interface Layer ". " Fido " refers to FidoBBS , " Opus " refers to Opus - CBCS BBS , and " SEAdog " refers to a Fidonet compatible mailer . The standards document that defines the ___MASK5___ protocol is maintained by the Fidonet Technical Standards Committee . In ___MASK65___ , a ___MASK85___ ( abbreviated sp ., with the plural form ___MASK85___ abbreviated spp .) is the basic unit of ___MASK87___ and a taxonomic rank . A ___MASK85___ is often defined as the largest group of organisms in which two individuals can produce fertile ___MASK32___ , typically by sexual reproduction . While this definition is often adequate , looked at more closely it is often problematic . For example , in a ___MASK85___ complex , the boundaries between closely related ___MASK85___ become unclear or disappear altogether . Other ways of defining ___MASK85___ include similarity of DNA , morphology , or ecological niche . The presence of locally adaptive traits may further subdivide ___MASK85___ into infraspecific taxa such as subspecies . Scorpions are predatory arachnids of the ___MASK16___ Scorpiones . They have ___MASK23___ legs and are easily recognized by the pair of grasping pedipalps and the narrow , segmented tail , often carried in a characteristic forward curve over the back , ending with a venomous stinger . Scorpions range in size from 9 mm / 0 . 3 in . (" Typhlochactas mitchelli ") to 23 cm / 9 in . (" Heterometrus swammerdami "). Horseshoe crabs are marine arthropods of the ___MASK75___ Limulidae and ___MASK16___ Xiphosura or Xiphosurida , that live primarily in and around shallow ocean waters on soft sandy or muddy bottoms . They occasionally come onto shore to mate . They are commonly used as bait and in fertilizer . In recent years , a decline in the population has occurred as a consequence of coastal habitat destruction in Japan and overharvesting along the east coast of North America . Tetrodotoxin may be present in the roe of species inhabiting the waters of Thailand . Because of their origin 450 million years ago ( Mya ), horseshoe crabs are considered living fossils . Centipedes ( from Latin ___MASK83___ ', " hundred ", and ', "" foot "") are arthropods belonging to the class Chilopoda of the subphylum Myriapoda . They are elongated metameric creatures with one pair of legs per body segment . Centipedes are known to be highly venomous , and often inject paralyzing venom . Despite the name , centipedes can have a varying number of legs , ranging from 30 to 354 . Centipedes always have an odd number of pairs of legs . Therefore , no centipede has exactly 100 legs . A key trait uniting this group is a pair of venom claws or forcipules formed from a modified first appendage . Centipedes are predominantly carnivorous . In ___MASK65___ , an ___MASK34___ is any contiguous living system , such as an animal , plant , fungus , archaeon , or bacterium . All known types of organisms are capable of some degree of response to stimuli , reproduction , growth and development and homeostasis . An ___MASK34___ consists of one or more cells ; when it has one cell it is known as a unicellular ___MASK34___ ; and when it has more than one it is known as a multicellular ___MASK34___ . Most unicellular organisms are of microscopic scale and are thus loosely described as microorganisms . Humans are multicellular organisms composed of many trillions of cells grouped into specialized tissues and organs . Atelocerata is a proposed ___MASK94___ of arthropods that includes Hexapoda ( insects and a few related taxa ) and Myriapoda ( millipedes , centipedes , and similar taxa ) , but excludes Crustacea ( such as shrimp and lobsters ) and Chelicerata ( such as spiders and horseshoe crabs ) . The name is currently used interchangeably with Tracheata . or Uniramia sensu stricto . It is an extensive division of arthropods comprising all those that breathe by tracheae , as distinguished from Crustacea , which breathe by means of gills . The name Tracheata is an older term , originally proposed by Ernst Haeckel in 1866 as a grouping of arachnids , myriapods and insects . Tracheata was redefined to exclude arachnids by Pocock in 1893 . ( reviewed in ) The name Atelocerata was first proposed by Richard Heymons in 1901 , and the two names are considered equivalent . The status of Atelocerata as a true ___MASK94___ is now doubted by molecular phylogenetic studies . Some recent authors have viewed the crustaceans as more closely related to hexapods than myriapods are . If this is true , then characters shared by hexapods and myriapods , but not crustaceans , must be the result of either convergence , or secondary loss in the Crustacea . A ___MASK94___ ( from , " klados ", " branch ") is a group of organisms that consists of a common ancestor and all its lineal descendants , and represents a ___MASK60___ " branch " on the " tree of life ". Ants are eusocial insects of the ___MASK75___ Formicidae and , along with the related wasps and bees , belong to the ___MASK16___ Hymenoptera . Ants evolved from wasp - like ancestors in the Cretaceous ___MASK29___ , about 99 million years ago and diversified after the rise of flowering plants . More than 12 , 500 of an estimated total of 22 , 000 species have been classified . They are easily identified by their elbowed antennae and the distinctive node - like ___MASK48___ that forms their slender waists . A lineal ___MASK15___ , in legal usage , is a blood relative in the direct ___MASK77___ of ___MASK92___ - the children , grandchildren , great - grandchildren , etc . of a person . In a legal procedure sense , lineal ___MASK92___ refers to the acquisition of estate by inheritance from grandparent to parent and parent to child , whereas collateral ___MASK92___ refers to the acquisition of estate or real ___MASK19___ by inheritance from sibling to sibling , and cousin to cousin . ___MASK74___ spiders , also called Pantopoda or pycnogonids , (' pycno -' closely packed , ' gonid ' gonidia ) are marine arthropods of class Pycnogonida . They are cosmopolitan , found especially in the Mediterranean and Caribbean Seas , as well as the Arctic and Antarctic Oceans . There are over 1300 known species , ranging in size from to over in some deep water species . Most are toward the smaller end of this range in relatively shallow depths ; however , they can grow to be quite large in Antarctic waters . Uniramia (" uni " - one , " ramus " - ___MASK13___ , i . e . ___MASK60___ - branches ) is a group within the arthropods . In the past this group included the Onychophora , which are now considered a separate category . The group is currently used in a narrower sense . Uniramia is one of three subphyla in Arthropoda classification suggested by Sidnie Manton . This classification divided arthropods into a three - phyla polyphyletic group , with phylum Uniramia including the Hexapoda ( insects ), Myriapoda ( centipedes and millipedes ) and the Onychophora ( velvetworms ). The discovery of fossil lobopods , determined to be intermediate between onychophorans and arthropods led to the splintering of the Lobopoda and Onychophora into separate groups . This redefined the Uniramia as strictly " true " arthropods with exoskeletons and jointed appendages . Uniramians have strictly uniramous appendages . An arthropod ( from Greek " arthro -", ___MASK8___ + " podos ", foot ) is an invertebrate animal having an exoskeleton ( external ___MASK24___ ), a segmented body , and jointed appendages ( paired appendages ). Arthropods form the phylum Arthropoda , which includes the insects , arachnids , myriapods , and crustaceans . Arthropods are characterized by their jointed limbs and cuticle made of chitin , often mineralised with calcium carbonate . The arthropod body plan consists of segments , each with a pair of appendages . The rigid cuticle inhibits growth , so arthropods replace it periodically by moulting . Their versatility has enabled them to become the most species - rich members of all ecological guilds in most environments . They have over a million described species , making up more than 80 % of all described living animal species , some of which , unlike most animals , are very successful in dry environments . Sidnie Milana Manton , FRS ( 4 ___MASK84___ 1902  2 January 1979 ) was a British entomologist . Onychophora ( from Ancient Greek , " onyches ", " claws "; and " pherein ", " to carry "), commonly known as velvet worms ( due to their velvety texture and somewhat wormlike appearance ) or more ambiguously as peripatus ( after the first described ___MASK42___ , " Peripatus "), is a phylum of elongate , soft - bodied , many - legged Panarthropods . In appearance they have variously been compared to worms with legs , caterpillars , and slugs . They prey upon smaller animals such as insects , which they catch by squirting an adhesive slime . Approximately 200 species have been described , although the true number of species is likely greater . The two extant families of velvet worms are Peripatidae and Peripatopsidae . They show a peculiar distribution , with the peripatids being predominantly equatorial and tropical , while the peripatopsids are all found south of the equator . It is the only phylum within animalia that is wholly endemic to terrestrial environments . Velvet worms are considered close relatives of the Arthropoda and Tardigrada , with which they form the ___MASK51___ Panarthropoda . This makes them of palaeontological interest , as they can help reconstruct the ancestral arthropod . In modern zoology , they are particularly renowned for their curious mating behaviour and for bearing live young . The subphylum Chelicerata ( or ; New Latin , from French " chélicère ", from Greek " khl " " claw , chela " and " kéras " " horn ") constitutes one of the major subdivisions of the phylum Arthropoda . It contains the horseshoe crabs , ___MASK74___ spiders , and arachnids ( including scorpions and spiders ).