Kingdom AnimaliaPhylum Arthropoda

Arthropods• “joint-foot”• Have jointed appendages modified for

different functions• Largest phylum of animals

Exoskeleton

• Hard, protective exterior skeleton• Made of protein & chitin• Flexible for joint movement• Doesn’t grow w/ animal, must shed old to

produce new= molting• Limits size of arthropods• Highly developed nervous system

Cicada Moulting

Subphylum- Crustaceans

• Include barnacles, krill, shrimps, lobsters, crabs

• 3 main body regions– Head– Thorax– Some have fused head/thorax = cephalothorax– Abdomen

• Each body segment has pair of appendages

Crustaceans, cont’d

• Appendages include:– Sensory antennae– Mandibles/maxillae: for feeding– Walking legs– Legs modified for swimming, reproduction, feeding, and

defense• Gas exchange through body or using gills• Vary in reproduction• Most have separate sexes• Most fertilization internal

Types of Crustaceans• Krill– Pelagic, shrimp-like animals– 3-6 cm long– Filter-feeders, feed primarily on zooplankton– Most bioluminescent– Extremely important feed animal. Primary food of

several whale species

OM NOM NOM

• Barnacles– Sessile (don’t move)– Can cause problems for ships by attaching to

hulls & causing increased friction– Some attach to whales and large fish

More Crustaceans

• Decapods (“ten feet.”)• Shrimps, lobsters, crabs• Largest in number & size• 5 pairs walking legs usually w/ claws on first• Shrimps & lobsters: distinct & elongate

abdomens• Crabs: small abdomen, broad cephalothorax,

highly mobile

Chelicerates-Subphylum• Include spiders, ticks, scorpions, horseshoe crabs

Horseshoe Crabs• Not true crabs• Live in shallow coastal

waters• 3 parts to body:– Cephalothorax-largest part of

body, obvious appendages– Abdomen-smaller, contains

gills– Telson- long spike, used for

steering & defense• Can walk or swim• Males smaller than females

6 pairs of appendages

Chelicerae(ka-LIS-er-ree): modified for feeding, replaces mouthparts