Phylum Arthropoda
description
Transcript of Phylum Arthropoda
Phylum ArthropodaSpiders, crabs, millipedes, insects, scorpions and lobsters
General informationLargest animal groupHave segmented bodiesBilateral symmetry, 3 cell layers
and a coelomPhylum name means “jointed feet”Has an exoskeleton made out of
protein and chitin (this is heavy and cumbersome, so arthropods can only get so large before they would collapse under there own weight)
Such a big group it is divided into four “subphyla” Trilobita: extinct nowChelicerta: spiders, scorpions,
etcCrustacea: crabs, lobsters, etcUniramia: millipedes,
centipedes and all insects
Subphylum ChelicertaClass ArachnidaSpiders, scorpions, ticks,
mites…..All have 4 pairs (8) walking
legsMost are carnivorous
Subphylum ChelicerataClass merostomata: horseshoe crabs
“living fossils”Not really crabs at all
All chelicerates have a body divided into a cepalothorax and abdomen
Unique to chelicerates are two pairs of appendages attached near mouth:Chelicerae: spiders use these to
bite/paralyze prey, and then inject enzymes that liquefy the prey so they can suck the “juice” out
Pedipalps: for handling prey, scorpions have large ones modified into claws
All spiders produce silk, some spin webs using “spinnerets”
Ticks and mites are usually parasites
Subphylum Crustacea(not focusing on one class)
Crabs, prawns, lobster, crayfish, copepods, water fleas….
Primarily aquatic Vary widely in size (microscopic to 6
m) Usually have a hard skeleton
reinforced with calcium Usually have 2 pairs of antennae and
a pair of mandibles
Have a head, thorax and abdomen
(these may be fused into cephalothorax)
Appendages vary greatly, crayfish have claws, walking legs, swimmerets and uropods
Subphylum UniramiaClass chilipodaCentipedesI pair of legs per segmentcarnivores
Subphylum UniramiaClass DiplopodaMillipedes2 pairs of legs per segmentscavengers
Subphylum UniramiaClass Insecta
HUGE groupAll have head, thorax and
abdomen3 pairs of legs attached to
thorax