ARTHROPODS Mr. Taylor Survey of the Animal Kingdom Rainier High School

ARTHROPODS  Arthro means “joint”  pod means “foot”, so Arthropod means “joint foot”  This is the first phylum to have jointed appendages:  Legs  Antennae  Mouthparts

ARTHROPODS  3 Sub-phyla  Uniramia (have jaws)  Includes insects, centipedes, millipedes  Crustacea (have a shell)  Includes lobsters, shrimp, crabs, pill bugs  Chelicerata (have horn-like claw/fang)  Includes spiders, ticks, mites, scorpions

ARTHROPOD CHARACTERISTICS  Arthropods have an articulated (jointed) exoskeleton with appendages.  Is secreted by and attached to epidermis.  Provides muscular attachment, allows movement when muscles contract.  Serves as protection from predators  Is waterproof: no water out or in  Prevents dehydration: allows for terrestrial forms  Keeps them dry (both from rain and watery environments).

ARTHROPOD CHARACTERISTICS AArthropods have an articulated (jointed) exoskeleton with appendages. HHelps grind food (jaws, pincers, fangs) FForms wings (allows flight) NNot all is good with rigid exoskeletons! TThey don’t grow so must be shed periodically HHigh energy cost to replace DDanger from predators while being replaced.

 All arthropods are segmented  Seems to indicate that annelids (earthworms and friends) were ancestors.  Bilateral symmetry, 3 tissue layers  Endoderm, ectoderm, mesoderm  Have a true coelom  Mouth-to-anus tubular digestive system

ARTHROPOD CHARACTERISTICS  Nervous system  Ladder-like: 2 nerve cords run ventrally and are connected at each segment  The anterior ganglia are enlarged enough to be called a BRAIN! but exhibit little control or “thought” function. Most of its action is inhibition.  Grasshoppers hop or fly  Praying mantis predatory/mating behavior.

ARTHROPOD CHARACTERISTICS  Respiratory system  Insects have a system of tracheae and spiracles (p 745 in your text)  Arachnids have “book lungs” (p 741)  Crustaceans have gills.  Circulatory system  Arthropods have an open circulatory system.

ARTHROPOD CHARACTERISTICS  Excretory system  Insects and spiders use Malpighian tubules to concentrate and eliminate nitrogenous and other wastes by simple diffusion.  Aquatic arthropods (crustaceans) use either simple diffusion through the gills or “green glands” to excrete nitrogenous wastes.