Phylum Arthropoda

Phylum Arthropoda - I Phylum Arthropoda a b includes spiders insects lobsters and others characteristics i jointed appendages(arthros jointed podes

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I. Phylum Arthropoda a. includes spiders, insects, lobsters, and others b. characteristics i. jointed appendages (arthros – jointed, podes – feet); may be modified as mouth parts, antennae, and legs ii. exoskeleton – cuticle composed primarily of chitin iii. segmented – often fused into sections or tagmata (tagmatization important in arthropod evolution) iv. all have a distinct head with a brain; sometimes head and thorax are fused into a cephalothorax , and sometimes several segments fused into an abdomen c. internal features i. no cilia ii. limited coelom iii. open circulatory system iv. respiratory system 1. respiration across the cuticle is common, especially in the smaller arthropods d. excretory system i. varies depending on group A. Subphylum Celcierata- spiders, horseshoe crabs, and sea spiders A. spiders, horseshoe crabs, and sea spiders B. lack jaws; first pair of appendages are mouthparts called chelicerae (fangs in some) C. second pair of appendages are pinchers or feelers ( pedipalps ) a. three classes: Merostomata , Arachnida , and Pycnogonida B. Class Merostomata (grade if fossils are included; clade for living members) – horseshoe crabs a. pedipalps appear like legs (as do chelicerae to some extent) – appear to have extra legs b. 5 pairs of book gills c. shell called a carapace d. long “tail” spine called telson C. Class Arachnida (clade) – arachnids a. include harvestmen, scorpions, spiders, mites, and ticks b. two body segments: prosoma (cephalothorax) and opisthosoma (abdomen) c. four pair of walking legs (8 legs) from prosoma d. feeding i. most are carnivorous ii. exception: mites are mostly herbivorous iii. can ingest only liquefied food e. Order Opiliones – harvestmen, or daddy longlegs i. oval, compact body with extremely long, slender legs ii. most are predators of insects and arachnids iii. females have an ovipositor for laying eggs f. Order Scorpiones – scorpions i. pedipalps are pinchers ii. stinger in last segment of abdomen
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iii. most ancient group of terrestrial arthropods (425 MYA)
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This note was uploaded on 04/17/2008 for the course BIOL 1030 taught by Professor Folkerts during the Spring '07 term at Auburn University.

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Phylum Arthropoda - I Phylum Arthropoda a b includes spiders insects lobsters and others characteristics i jointed appendages(arthros jointed podes

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