Download Ch 29 - Crestwood Local Schools

Ch 29
Phylum Arthropoda
More kinds of these than any other kind of animal!
~ evolved from Annelids
~ Trilobites - 1st animals with eyes capable of forming images
- lived in seas
~ 1st terrestrial arthropod thought to be scorpions about 425
mill. yrs. ago
Characteristics:
~ jointed appendages
~ segmentation
~ head - some have cephalothorax = head fused w/thorax ex:
lobsters, spiders
~ exoskeleton - hard outer layer
~ compound eyes - many little eyes form one big eye
- some have a simple eye but can only see light and dark
~ spiracles -openings that let air into trachea that run
through the body
- most have these except crustaceans and spiders
~ circulatory system is open - heart squeezes blood into open
body spaces
~ malphigian tubules - excretory system that conserves
water and eliminates waste
~ wings - seen on insects only!
Arthropods also molt to grow into larger bodies - shed
exoskeleton! Cool!
Arachnids: spiders, scorpions, mites
* have chelicerae as foremost appendage
* have palps = catch and handle prey
* all are carnivores except mites
* have no jaws!
* must liquefy prey and "drink" it
* mostly terrestrial
Scorpions: ~ palps are pincers
~ venomous stinger at end of tail
Spiders: ~ have fangs
~ make webs of silk (most)
~ Brown Recluse and Black Widow are most
dangerous in U.S.
Mites: ~ very small
~ terrestrial
~ freshwater or marine
Crustaceans: crabs, lobsters, shrimp, crayfish, pillbugs
* have jaws
* live in freshwater and marine - some terrestrial
* some have branched appendages at end
* have a distinct larval form
* have exoskeletons that harden by CaCO3
* 2 pairs of antennae
* most have 3 pairs of chewing append.
* legs attached to abdomen as well as thorax
*all breathe with gills
Millipedes and Centipedes:
Millipedes = "thousand foot"
- have 2 pairs of legs per segment = about 60 total
legs
- are herbivores
- distinct heads
Centipedes = "hundred foot"
- have 1 pair of legs per segment - about 30 total
legs
- are carnivores - inject venom by fangs!
Insects:
* Largest group of organisms in the world!
* primarily terrestrial
* most are small
* have same general body plan: head, thorax, abdomen
- 3 pairs of legs attached to thorax
- 1 pair antennae
* wings on most - fleas, lice, and silverfish don't have
~ attached to thorax
* 90% of all undergo complete metamorphosis:
~ life cycle: eggs - larva - pupa - adult
ex: butterflies!
*10% undergo incomplete metamorphosis:
~life cycle: eggs - nymph - young adult - adult
ex: grasshoppers
Some insects have a complex social system:
~ ants, bees, termites
* have a single queen that produces all offspring
*only the king can mate with her
* workers and soldiers are sterile