PENTASTOMID

any of about 70 species of tiny parasites belonging to the Pentastomida, usually considered a class. Pentastomids are considered to lie between annelids and arthropods in evolutionary development. They range from a few millimetres to 14 cm (about 6 inches) in length and lack respiratory, circulatory, and excretory organs. Pentastomids live in the respiratory systems of vertebrate hosts. Although they are mostly tropical or subtropical, those with homoiothermic (warm-blooded) hosts may also be found in cold regions. Reptiles are the most common victims of pentastomid infestation. Porocephalus is parasitic in snakes and rodents. Lingulata species parasitize various mammals, including dogs. A few species are of medical interest because they infest human hosts.