bugs lice and fleas 2010 - 11/18/2010 ARTHROPODS The word...

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11/18/2010 1 Bugs, Lice, and Fleas by Dwight Bowman ARTHROPODS The word “arthropod” means jointed body. The most numerous organisms on earth, so in some respects, the exoskeleton has been more successful than the backbone. ortunately only a few are truly parasitic on humans. Fortunately, only a few are truly parasitic on humans. Primitive arthropods are suggested to have a form that consists of a body composed of a series of segments where each segment had a pair of jointed appendages, one on each side; down the center of the body extended the tube representing the digestive tract. The exoskeleton, that part which gives them that distinctive “crunch” if you ever happen to crush one, covers the outside of the body and is composed of chitin. To grow or to change their internal and external morphology (the process of metamorphosis), arthropods must change the external pp ) p g cuticle that covers their body. This they do through a process of laying down a new cuticle in a process called molting, and then, the old cuticle is shed or ecdysed. The body is composed of hollow spaces with a gut, heart (an open circulatory system), and gills or tracheae for supplying air. ARTHROPODS Four major groups of Arthopods: The Trilobites comprise a group known only from fossils. The Crustacea compose the group that includes the well pg p known shrimp, lobster, crab, and crayfish, along with the less well known copepods. The Cheliceriformes include the horseshoe crabs and the arachnids (the spiders, scorpions, mites, and ticks). The Uniramia include the Myriapods (millipedes), Chilopods (Centipedes), and the Insects (Hexapods). . There are some obvious differences in the morphology f insects and arachnids of insects and arachnids. Adult insects have 6 legs, adult arachnids have 8 legs. Adult insects have three major body divisions (head, thorax, and abdomen); adult arachnids have two basic body divisions (cephalothorax and abdomen). BUGS - HEMIPTERA The order Hemiptera (Heteroptera to some authors) form the group of bugs Majority are predacious or feed on plant juices True bugs tend to be relatively large in size and have a narrow neck that connects the rather thin head with large eyes to the thorax which has six gy well developed legs Characterized by a hinged proboscis that is folded under the head and thorax at rest but which is held such that it protrudes from the front of the insect when it is feeding by piercing the veins of a host or when sucking out body fluid from a plant or its prey The wings of the bugs tend to be covered on the anterior half with a leathery cuticle only apparent in the transparent posterior wing portion Development is via simple metamorphosis which five nymphal instars that feed in a fashion similar to their adult counterparts he two important groups in medicine are the The two important groups in medicine are the Kissing bugs and the Bed bugs
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11/18/2010 2 Triatoma Triatoma infestans
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This note was uploaded on 09/30/2011 for the course BIOMI 4170 at Cornell University (Engineering School).

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bugs lice and fleas 2010 - 11/18/2010 ARTHROPODS The word...

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