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Biology 112. Arthropods and Echinoderms. Includes animals such as crabs, spiders, and insects Segmented bodies, a tough exoskeleton (external body covering) and jointed appendages (legs and antennae that extend from the body wall)
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Biology 112 Arthropods and Echinoderms
Includes animals such as crabs, spiders, and insects • Segmented bodies, a tough exoskeleton (external body covering) and jointed appendages (legs and antennae that extend from the body wall) • Fewer body segments than worms and highly specialized appendages used for feeding, movement and other functions • Most only have 2-3 segments • Appendages include walking legs, antennae, wings and mouthparts Anthropods
Herbivores, carnivores and omnivores • Most receive gases through a network of tracheal tubes that extend throughout body • Openings are called spiracles • Others have book lungs • Aquatic organisms have gills • Eliminate wastes through structures called Malpighian tubules • internal fertilization (terrestrial) and external for aquatic Functions of Arthropods
Arthropods outgrow their skeletons and molt • The entire skeleton is shed and manufactures a larger one to take its place Arthropods and Exoskeleton
Classification is based on number of segments and appendages – particularly mouthparts • Crustaceans (Crustacea) • Chelicerates (Chelicerata) • Uniramians (Uniramia) Groups of Arthropods
Crabs, shrimp, lobster, crayfish, barnacles • Two pairs of antennae, 2-3 body segments (head, thorax and abdomen), chewing mouthparts called mandibles Crustaceans
Horseshoe crabs, spiders, ticks, and scorpions • Have mouthparts called chelicerae and 2 body segments • Four pairs of walking legs • Spiders spin webs of silk Chelicerates
Centipedes, millipeds and insects • Have jaws, one pair of antennae, unbranched appendages • Most body segments have one pair of legs each Uniramians
Three body parts – head, thorax and abdomen • Three pairs of legs attached to the thorax • Usually, a pair of antennae, a pair of compound eyes, and two pairs of wings • Can detect changes in colour and movement • Three pairs of appendages used for mouthparts • Growth usually involves metamorphosis, the process of changing shape and form • Some are harmful to humans and others helpful • The communicate using sound, chemical and other types of signals • Some are also capable of forming societies Insects
Sea stars, sea urchins, and sand dollars • Characterized by spiny skin, a water vascular system, and suction-like structures called tube feet • Have an endoskeleton, five part radial symmetry as adults and are all deuterosomes • Contain a water vascular system that is filled with fluid that carries out much of its life functions • A maldreporite Echinoderms