Information: - Uniramia ("uni" - one, "ramus" - branch, i.e. single-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. - Myriapoda is a subphylum of arthropods containing millipedes, centipedes, and others. The group contains over 13,000 species, 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 ten legs. - Lobsters comprise a family (Nephropidae, sometimes also Homaridae) of large marine crustaceans. - Atelocerata is a proposed clade 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 subphylum Chelicerata (or ; New Latin, from French "chelicere", from Greek "khl" "claw, chela" and "keras" "horn") constitutes one of the major subdivisions of the phylum Arthropoda. It contains the horseshoe crabs, sea spiders, and arachnids (including scorpions and spiders). - Millipedes are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name being derived from this feature. Each double-legged segment is a result of two single 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 group which also includes centipedes and other multi-legged creatures. - A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water and excretes carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are kept moist. The microscopic structure of a gill presents a large surface area to the external environment. - Insects (from Latin ', a calque of Greek ['], "cut into sections") are a class of invertebrates within the arthropod phylum that have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed legs, compound eyes and one pair of antennae. They are the most diverse group of animals on the planet, including more than a million described species and representing more than half of all known living organisms. The number of extant species is estimated at between six and ten million, and potentially represent over 90% of the differing animal life forms on Earth. Insects may be found in nearly all environments, although only a small number of species reside in the oceans, a habitat dominated by another arthropod group, crustaceans. - Centipedes (from Latin prefix ', "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. - A clade (from , "klados", "branch") is a group of organisms that consists of a common ancestor and all its lineal descendants, and represents a single "branch" on the "tree of life". - Horseshoe crabs are marine arthropods of the family Limulidae and order 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. - Pancrustacea is a clade , comprising all crustaceans and hexapods . This grouping is contrary to the Atelocerata hypothesis , in which Myriapoda and Hexapoda are sister taxa , and Crustacea are only more distantly related . As of 2010 , the Pancrustacea taxon is considered well accepted . The clade has also been called Tetraconata , referring to the square ommatidia of many of its members . That name is preferred by some scientists as a means of avoiding confusion with the use of '' pan- '' to indicate a clade that includes a crown group and all of its stem group representatives . - Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the Cretaceous period, 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 structure that forms their slender waists. - In biology, an organism 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 organism consists of one or more cells; when it has one cell it is known as a unicellular organism; and when it has more than one it is known as a multicellular organism. 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. - An arthropod (from Greek "arthro-", joint + "podos", foot) is an invertebrate animal having an exoskeleton (external skeleton), 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. What is the relationship between 'pancrustacea' and 'uniramia'?
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