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In Crustacea, the saccate metanephridia are associated with the antennae and form the antennal gland. In freshwater crustacea, the saccate metanephridia are especially large due to their role in osmoregulation; crustacea must remove large amounts of water from the tissues, as the cells are hypertonic to the surrounding water.
The three basic segments of the typical insect antenna are the scape or scapus (base), the pedicel or pedicellus (stem), and finally the flagellum, which often comprises many units known as flagellomeres. [10] The pedicel (the second segment) contains the Johnston's organ which is a collection of sensory cells. [11]
Coxal gland and its components. The coxal gland is a gland found in some arthropods, for collecting and excreting urine. They are found in all arachnids (with the exception of some Acari), and in other chelicerates, such as horseshoe crabs. [1] The coxal gland is thought to be homologous with the antennal gland of crustaceans.
An ionocyte (formerly called a chloride cell) is a mitochondrion-rich cell within ionoregulatory organs of animals, such as teleost fish gill, insect Malpighian tubules, crustacean gills, antennal glands and maxillary glands, and copepod Crusalis organs. [1]
The decapod (crustaceans, such as a crab, lobster, shrimp or prawn) is made up of 20 body segments grouped into two main body parts: the cephalothorax and the pleon . [1] [2] Each segment may possess one pair of appendages, although in various groups these may be reduced or missing. They are, from head to tail:
Malpighian tubules are slender tubes normally found in the posterior regions of arthropod alimentary canals. Each tubule consists of a single layer of cells that is closed off at the distal end with the proximal end joining the alimentary canal at the junction between the midgut and hindgut. Most tubules are normally highly convoluted.
Unlike many other crustaceans, the body is not clearly divided into segments. Most species have completely or partly lost their trunk segmentation, and there are no boundaries between the thorax and abdomen, and it has therefore been impossible to tell if the first pair of limbs after the maxillae belongs to the head or the thorax.
In the mosquito, the Johnston's organ houses ~15 000 sensory cells in males, [8] comparable to that in the human cochlea, [9] and approximately half as many in females. [10] Distinct populations of neurons are activated differently by deflections of antennae caused by gravity or by vibrations caused by sound or air movement.