“Crustacea”的概念、定义、翻译、参考文献-科学参考

Crustacea

Biology

In traditional classifications, a subphylum of arthropods containing over 35 000 species distributed worldwide, mainly in freshwater and marine habitats, where they constitute a major component of plankton. Crustaceans include shrimps, crabs, lobsters, etc. (see decapoda) and the terrestrial woodlice, all of which belong to the class Malacostraca; the barnacles (class Cirripedia); the water fleas (see daphnia), fairy shrimps and tadpole shrimps (see branchiopoda); and the copepods (see copepoda). The segmented body usually has a distinct head (bearing compound eyes, two pairs of antennae, and various mouthparts), thorax, and abdomen, and is protected by a shell-like carapace. Each body segment may bear a pair of biramous appendages used for locomotion, as gills, and for filtering food particles from the water. Appendages in the head region are modified to form jaws and in the abdominal region are often reduced or absent. Typically, the eggs hatch to produce a free-swimming nauplius larva. This develops either by a series of moults or undergoes metamorphosis to the adult form. Genetic and other molecular evidence now shows that the insects evolved from crustacean ancestors and that certain groups of crustaceans are more closely related to insects than to other crustaceans. Hence, although the evolutionary relationships of many crustacean lineages are still debatable, both groups are now placed in the clade Pancrustacea (see arthropod).
http://tolweb.org/Crustacea/2529 Overview of crustacean phylogeny at the Tree of Life web project

Geology and Earth Sciences

Diverse subphylum of mandibulate arthropods, the body usually divided into three parts: head, thorax, and abdomen. In some crustaceans (e.g. crayfish) the head and thorax may be joined to form the cephalothorax. The head bears two pairs of antennae, one pair of mandibles, and two pairs of maxillae. The limbs are biramous, and are adapted for a wide range of functions. Closely placed setae on the limbs function as filters in filter-feeding species. Respiratory gills are situated on the appendages, but vary greatly in location and number; they are absent only in very small species. In addition to the antennae, sense organs include a pair of compound eyes, and a small, dorsal, median, nauplius eye, comprising three or four closely applied ocelli (clusters of photoreceptors). The nauplius eye, characteristic of crustacean larvae, is absent in many adults; and some groups lack the compound eyes. Mainly marine, but there are many freshwater species, and a relatively small number have invaded the land. Four classes of crustaceans have an important fossil record. The Malacostraca (crabs, lobsters, woodlice, etc., Cambrian to Recent) includes the earliest crustaceans of the subclass Phyllocarida. The Branchiopoda (similar to modern water fleas, Lower Devonian to Recent) are valuable index fossils in non-marine strata. The Cirripedia (barnacles) occur from Upper Silurian to Recent, and the Ostracoda from Lower Cambrian to Recent. The living class Cephalocarida (e.g. Hutchinsonella) is thought to be closest to the ancestral crustacean stock, but the group is without any unequivocal fossil representative. Hexapods (Hexapoda) are believed to be descended from a crustacean, and hexapods and insects are grouped in the clade Pancrustacea.

单词	Crustacea
释义	Crustacea Biology In traditional classifications, a subphylum of arthropods containing over 35 000 species distributed worldwide, mainly in freshwater and marine habitats, where they constitute a major component of plankton. Crustaceans include shrimps, crabs, lobsters, etc. (see decapoda) and the terrestrial woodlice, all of which belong to the class Malacostraca; the barnacles (class Cirripedia); the water fleas (see daphnia), fairy shrimps and tadpole shrimps (see branchiopoda); and the copepods (see copepoda). The segmented body usually has a distinct head (bearing compound eyes, two pairs of antennae, and various mouthparts), thorax, and abdomen, and is protected by a shell-like carapace. Each body segment may bear a pair of biramous appendages used for locomotion, as gills, and for filtering food particles from the water. Appendages in the head region are modified to form jaws and in the abdominal region are often reduced or absent. Typically, the eggs hatch to produce a free-swimming nauplius larva. This develops either by a series of moults or undergoes metamorphosis to the adult form. Genetic and other molecular evidence now shows that the insects evolved from crustacean ancestors and that certain groups of crustaceans are more closely related to insects than to other crustaceans. Hence, although the evolutionary relationships of many crustacean lineages are still debatable, both groups are now placed in the clade Pancrustacea (see arthropod). http://tolweb.org/Crustacea/2529 Overview of crustacean phylogeny at the Tree of Life web project Geology and Earth Sciences Diverse subphylum of mandibulate arthropods, the body usually divided into three parts: head, thorax, and abdomen. In some crustaceans (e.g. crayfish) the head and thorax may be joined to form the cephalothorax. The head bears two pairs of antennae, one pair of mandibles, and two pairs of maxillae. The limbs are biramous, and are adapted for a wide range of functions. Closely placed setae on the limbs function as filters in filter-feeding species. Respiratory gills are situated on the appendages, but vary greatly in location and number; they are absent only in very small species. In addition to the antennae, sense organs include a pair of compound eyes, and a small, dorsal, median, nauplius eye, comprising three or four closely applied ocelli (clusters of photoreceptors). The nauplius eye, characteristic of crustacean larvae, is absent in many adults; and some groups lack the compound eyes. Mainly marine, but there are many freshwater species, and a relatively small number have invaded the land. Four classes of crustaceans have an important fossil record. The Malacostraca (crabs, lobsters, woodlice, etc., Cambrian to Recent) includes the earliest crustaceans of the subclass Phyllocarida. The Branchiopoda (similar to modern water fleas, Lower Devonian to Recent) are valuable index fossils in non-marine strata. The Cirripedia (barnacles) occur from Upper Silurian to Recent, and the Ostracoda from Lower Cambrian to Recent. The living class Cephalocarida (e.g. Hutchinsonella) is thought to be closest to the ancestral crustacean stock, but the group is without any unequivocal fossil representative. Hexapods (Hexapoda) are believed to be descended from a crustacean, and hexapods and insects are grouped in the clade Pancrustacea.
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