ARTHROPODS

Mr. TaylorSurvey 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 Arthropods have an articulated (jointed)

exoskeleton with appendages. Helps grind food (jaws, pincers, fangs) Forms wings (allows flight)

Not all is good with rigid exoskeletons! They don’t grow so must be shed

periodically High energy cost to replace Danger from predators while being replaced.

ARTHROPOD CHARACTERISTICS 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.