Definition, Characteristics, Evolution, Facts - Britannica crustacean, any member of the subphylum Crustacea (phylum Arthropoda), a group of invertebrate animals consisting of some 45,000 species distributed worldwide Crabs, lobsters, shrimps, and wood lice are among the best-known crustaceans, but the group also includes an enormous variety of other forms without popular names
List of crustaceans | Britannica This is a list of significant crustaceans, which are members of the subphylum Crustacea They are grouped taxonomically by class, with notable members of each class ordered alphabetically
Crustacean - Anatomy, Adaptations, Diversity | Britannica The fossil record, although fairly rich, has not solved any of the questions about the early evolution of the Crustacea The earliest of the definite fossil crustaceans are ostracods, a relatively specialized group
Crustacean - Aquatic, Arthropod, Exoskeleton | Britannica These two processes at the tail end of the body vary greatly in form; in many crustaceans they are short, but in some they may be as long as the rest of the body The Crustacea as a whole shows great variation in the number of somites and the amount of fusion that has taken place
Characteristics of crustaceans | Britannica crustacean , Any member of the 45,000 arthropod species in the subphylum Crustacea Distributed worldwide, crustaceans are distinguished by having two pairs of antenna-like appendages in front of the mouth and other paired appendages near the mouth that act like jaws
Malacostracan | Definition, Characteristics, Examples, Classification . . . Lobsters, crabs, hermit crabs, shrimp, and isopods are all malacostracan crustaceans Malacostracans are the most numerous and most successful of the four major classes of Crustacea Their members constitute more than two-thirds of all living crustacean species
Pill bug | Isopod, Armadillidiidae, Roll-up Bug | Britannica Pill bug, any of the terrestrial crustaceans of the families Armadillididae and Armadillidae (order Isopoda) When disturbed, the pill bug rolls itself up into a tiny ball Like the related sow bug (q v ), it is sometimes called the wood louse For mollusks also known as pill bugs, see chiton The
Crustacean - Arthropod, Aquatic, Decapod | Britannica There is no universal agreement on the classification of the Crustacea and even less agreement on the interrelationships between the various groups Alternative classifications of the classes Branchiopoda and Malacostraca are discussed below
Amphipod | Crustacean, Shrimp-Like, Marine Species | Britannica Amphipod, any member of the invertebrate order Amphipoda (class Crustacea) inhabiting all parts of the sea, lakes, rivers, sand beaches, caves, and moist (warm) habitats on many tropical islands