Isopoda
Isopoda is an order of crustaceans that includes woodlice and their relatives. Isopods live in the sea, in fresh water, or on land. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, and five pairs of branching appendages on the abdomen. Females brood their young in a pouch under their thorax.
About Isopoda in brief
Isopoda is an order of crustaceans that includes woodlice and their relatives. Isopods live in the sea, in fresh water, or on land. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, and five pairs of branching appendages on the abdomen. Females brood their young in a pouch under their thorax. Some species are able to roll themselves into a ball as a defense mechanism or to conserve moisture. There are over 10,000 species of isopod worldwide, with around 4,500 species found in marine environments, mostly on the seabed, 500 species in freshWater, and another 5,000. species on land, and the order is divided into eleven suborders. The first five abdominal segments each bear a pair of biramous pleopods, the last pair of uropods, the second pair of pleopod, and sometimes the first, are modified into thin, permeable cuticles which act as gills for exchange of gas. In some terrestrial species isopods, such as Peracarida, there is a cosmopolitan distribution, with over 10 million species in the wild. The fossil record of Isopoda dates back to the Carboniferous period, at least 300 million years ago, when isopoda lived in shallow seas. The name Isopod is derived from the Greek roots iso- and -pod.
Classified within the arthropods, isopODs have a chitinous exoskeleton and jointed limb. The body plan consists of a head, a thorax with eight segments, and an abdomen with six segments, some of which may be fused. The eyes are compound and unstalked and the mouthparts include a pair with palps and lacinia mobilis. In most species these are used for locomotion and are of much the same size, morphology and orientation, giving the order its name ‘Isopod’, from theGreek equal foot. Some species have clawed, gripping terminal segments. The pereopods are not used in respiration, as are the equivalent limbs in amphipods, but the coxae are fused to the tergites to form epimera. In mature females, some or all of the limbs have appendages known as oostegites which fold underneath theThorax and form a brood chamber for the eggs. In mature female species, the gonopores are on the ventral surface of segment eight and in the females, they are in a similar position on segment six. The head is fused with the first segment of the Thorax to form the cephalon. The abdominal segments, starting with the sixth segment, is fused to telson to form a telson.
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This page is based on the article Isopoda published in Wikipedia (as of Dec. 02, 2020) and was automatically summarized using artificial intelligence.
