Chapter 14 and 15
Phylum Arthropoda
Jointed appendages (more strength and
coordination)
Exoskeleton (like roundworms, when they
outgrow their exoskeleton, molt and secrete a new
one)
Very diverse (more species of arthropods than
any other phylum)
Open circulatory system (blood vessels empty
into the body cavity) hemocoel (blood vessels and
coelom together)
Metamorphosis (body plan changes during
development)
Groups of arthropods
Trilobites (extinct Subphylum)
Chelicerata (have chelicerae)
Arachnids (spiders, scorpions, ticks, mites)
Horseshoe crabs (aquatic)
Sea spiders
Crustaceans: biramious, susceptible to water loss
(usually aquatic)
1) Malacostracans (Decapods: (crabs,
lobsters, crayfish), shrimp, mysids, krill, isopods,
amphipods) (big group)
2) Branchiopodans (fairy shrimp and brine
shrimp)
3) Maxillopodans (copepods and barnacles)
Chapter 15 Hexapods and Myriapods
These two subphyla have waxy exoskeletons
(unlike crustaceans), mostly terrestrial,
uniramous appendages
Myriapoda
Millipedes (2 pairs of legs per segment)
typically cylindrical, detritivores
Centipede (1 pair of legs per segment),
predators, venomous, longer legs than millipede,
flatter body
Pauropoda and Symphyla
Hexapoda (insects and former insects)
Insects (three segments, head, thorax,
abdomen; three pairs of legs (thorax), 2 pairs of
wings, 1 pair of antennae; specialized mouthparts)
First flying animals
75% of known species are insects
Tracheal gas exchange (decentralized gas
exchange) system of tubes for gas exchange and
gas distribution
Limited thermoregulation
Eusocial (hive)
Orders
1) Beetles (25% of all species)
Forewings are hardened and function for
protection
2) lepidopterans (butterflies and moths)
Coiled proboscis
3) true flies (dipterans) house flies, mosquitos,
fruit flies, horse flies; one pair of wings, one pair
of halteres
4) hymenopterans (ants, bees, wasps (not
termites))
Frequently eusocial
Related phyla
Tardigrade (water bears)
Ohychophora (velvet worms)