Context: Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) (= short, = tail), usually entirely hidden under the thorax. They live in all the world's oceans, in fresh water, and on land, are generally covered with a thick exoskeleton and have a single pair of claws. Many other animals with similar names  such as hermit crabs, king crabs, porcelain crabs, horseshoe crabs, and crab lice  are not true crabs., King crabs are a superfamily of crab-like decapod crustaceans chiefly found in cold seas. Because of their large size and the taste of their meat, many species are widely caught and sold as food, the most common being the red king crab ("Paralithodes camtschaticus")., Raninoida is a taxonomic section of the crabs, containing a single superfamily, Raninoidea. This group of crabs is unlike most, with the abdomen not being folded under the thorax. It comprises 46 extant species, and nearly 200 species known only from fossils., Hermit crabs are decapod crustaceans of the superfamily Paguroidea., An exoskeleton (from Greek , "éx" "outer" and , "skeletos" "skeleton") is the external skeleton that supports and protects an animal's body, in contrast to the internal skeleton (endoskeleton) of, for example, a human. In usage, some of the larger kinds of exoskeletons are known as "shells". Examples of animals with exoskeletons include insects such as grasshoppers and cockroaches, and crustaceans such as crabs and lobsters. The shells of certain sponges and the various groups of shelled molluscs, including those of snails, clams, tusk shells, chitons and nautilus, are also exoskeletons. Some animals, such as the tortoise, have both an endoskeleton and an exoskeleton., The tail is the section at the rear end of an animal's body; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, reptiles, and birds. While tails are primarily a feature of vertebrates, some invertebrates including scorpions and springtails, as well as snails and slugs, have tail-like appendages that are sometimes referred to as tails. Tailed objects are sometimes referred to as "caudate" and the part of the body associated with or proximal to the tail are given the adjective "caudal"., In some taxonomic systems, Podotremata is the smaller of the two sections making up the crabs (Brachyura). Morphological and molecular analyses do not reveal a monophyletic Podotremata, and so the most recent classifications divide "Podotremata" into three sections: Dromiacea, Cyclodorippoidea and Raninoida., The abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The region occupied by the abdomen is termed the abdominal cavity. In arthropods it is the posterior tagma of the body; it follows the thorax or cephalothorax. The abdomen stretches from the thorax at the thoracic diaphragm to the pelvis at the pelvic brim. The pelvic brim stretches from the lumbosacral joint (the intervertebral disc between L5 and S1) to the pubic symphysis and is the edge of the pelvic inlet. The space above this inlet and under the thoracic diaphragm is termed the abdominal cavity. The boundary of the abdominal cavity is the abdominal wall in the front and the peritoneal surface at the rear., Dromiacea is a group of crabs , ranked as a section . It contains 240 extant and nearly 300 extinct species . Where they are considered to form a monophyletic group , Dromiacea and two other groups of crabs , namely the Raninoida and Cyclodorippoidea , may be collected together into the Podotremata , each at the rank of subsection ; morphological and molecular evidence argue against such a grouping . The larvae of Dromiacea resemble those of the Anomura more closely than those of other crabs . This may simply reflect their basal position in the crab phylogeny . The fossil record of Dromiacea reaches back at least as far as the Jurassic , and , if Imocaris is indeed a member , into the Carboniferous . The superfamily Eocarcinoidea , containing Eocarcinus and Platykotta , was previously considered to be a member of the Dromiacea , but has since been transferred to the Anomura ., 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., The thorax or chest (from the Greek  "thorax" "breastplate, cuirass, corslet" via ) is a part of the anatomy of humans and various other animals located between the neck and the abdomen. The thorax includes the thoracic cavity and the thoracic wall. It contains organs including the heart, lungs, and thymus gland, as well as muscles and various other internal structures. Many diseases may affect the chest, and one of the most common symptoms is chest pain., Subject: dromiacea, Relation: parent_taxon, Options: (A) animal (B) brachyura (C) hermit (D) human (E) insects (F) king crab (G) mya (H) paralithodes (I) thorax (J) tortoise (K) xiphosura
Output: brachyura