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50 terms

Chapter 26 Arthropods and Echinoderms

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Phylum Arthropoda
Latin for "Jointed Legs"
Arthropod features
segmented invertebrates with bilateral symmetry and coelomate body cavity.
head
mouth parts for feeding and various types of eyes
Thorax
middle body region to which legs and wings are attached.
abdomen
posterior body region: contains digestive structures and reproductive organs.
Arthropod exoskeleton
hard thick outer covering made of chitin.
protects and supports internal organs and tissues.
disadvantages of arthropod exoskeleton
relatively heavy so keeps size small in order to grow must molt.
molting
shedding and replacing exoskeleton
Appendage
any structure like a leg or antenna that grows out of body of animal.
advantages of appendages
allow flexibility and variety of functions and movements.
Feeding and digestion: arthropod
complete one way digestive system from mouth to anus.
gills
feathery structures used by aquatic arthropods for oxygen and carbon dioxide exchange found in crustaceans.
tracheal tubes
system of branching tubules carrying oxygen through body found in most insects.
book lungs
air filled chambers hat look like pages in a book: spiders.
Malpighian tubules
remove cellular wastes from blood.
Circulation in arthropods
open circulatory system
reproduction of arthropods
sexual with separate sexes.
compound eye
multiple lenses that detect movement and color.
simple eye
1 lens that detects light.
antennae
stalklike structure that detect changes in environment (movement and sound)
tympanum
hearing membrane
Class Crustracea
crayfish,lobsters. 2 pairs of antennae. first pair of legs are chelipds. large claws. swimmerets.
chelipeds
Claws. adapted to crush and catch food.
swimmerets
appendages used for reproduction and swimming.
Class Arachnida
spiders,scorpians, mites,ticks. 2 body regions (cephalothorax and abdomen) 4 pairs of walking legs. no antennae. chelicerae.
Chelicerae
modified pinches/ fangs for holding food or injecting venem.
spiders
capable of constructing specific kinds of webs with spinnerets
spinnerets
allow spiders to spin silk from silk glands.
class Merostomata
horseshoe crab..living fossils have remained unchanged for 20 million years.
class insecta
largest, most diverse group of arthropods. successful b/c of adaptions. can live many places. flies,butterfly.
Metamorphosis
change in body shape and form in development.
complete metamorphosis
4 stages: Egg, Larva, Pupa, Adult. most insects. butterflies.
Larva
wormlike, eats grows and molts.
Pupa
resting stage surrounded by cocoon.
incomplete metamorphosis
hatch from eggs as nymphs: grasshoppers. cockroaches.
nymphs
look like miniature adults but lack wings and mature sex organs.
Class Chilopoda
carnivores with flattened wormlike bodies
Centipedes
centipedes
have long, segmented bodies, each segment has one pair of jointed legs.
Class Diplopoda
scavengers with cylindrical bodies. Millipedes.
Millipeda
have two pairs of appendages per body segment.
Phylum Echinodermata
Greek: "Spiny Skinned", all are marine, radial symmetry as adults. larvae have bilateral.
Echinoderm endoskeleton
consists of calcium carbonate spiny plates covered by a thin layer of skin.
Pedicellariae
pincer like appendages on spines of sea starts and sea urchins. catch food, protect. clean body.
Water Vascular system def:
system of fluid filled, closed tubes that work together enabling echinoderms to move and get food.
Madreporite plate
sieve-like, disk shaped opening on upper surface of body. water enters and leaves through this.
Ampullae
contract and squeeze water into tube feet
tube feet
hollow, thin walled tubes ending in suction cups. movement by pushing out and pulling in tube feet.
Sea star
5 arm arranged around a central disk, if rays are lost can be replaced through regeneration.
Brittle Stars
Most brittle stars have five arms. Arms are thin and very flexible.
Water vascular system path
madreporite plate--stone canal--ring canal--radial canal--ampullae--tube feet.