Phylum Arthropoda Largest phylum of animals 900 000

Phylum Arthropoda

• • Largest phylum of animals. >900, 000 species 78% of all animals are arthropods “Most successful animal group” • Arthropod = “jointed foot (appendages)” • Probable evolution from the annelids (elongated, segmented bodies)

• -Well developed organ systems • -One pair of jointed appendages per segment • -Segments are fused …. Head/thorax/abdomen • -Open circulatory system (blood rarely in vessels)

• Dorsal heart • -Ventral nervous system • -Distinct head, often with compound eyes • -Many have wings

Classification Domain: Kingdom: Phylum: Eukarya Animalia Arthropoda 4 Subphyla • 1) Trilobita : extinct sea dwellers • 2) Chelicerata : “Arachnids” • 3) Crustacea : Crabs/lobsters/shrimp • 4) Uniramia : Centipedes, millipedes, insects

Trilobite

• Through evolution, segmentation has decreased! • 3 “BIG” Arthropod Characteristics – Jointed Appendages – Segmented bodies – Exoskeleton

Exoskeleton • Advantages: Protection, support, prevents water loss, anchor for muscle tissue • Disadvantages: Non-living (don’t grow). Must molt. Leaves them vulnerable to predators. Can be heavy – limits mobility. • Exoskeleton is actually a set of hinged plates.

• Molting: Very energy consuming. Leaves them vulnerable to predators • Appendage types: walking legs, wings, antennae, claws, flippers, mouthparts • Feeding strategies: Herbivores, Carnivores, Parasites, Filter feeders, detritus feeders. • Mouthpart types: Chewing, sucking, soaking (spongey), and lapping.

• Respiration: Gills, book lungs, tracheal tubes • Gills: Feathery, found under exoskeleton. Mouthpart and appendage movement keeps a steady flow of water over the gills. Aquatic Arthropods only – Crustaceans. • Book lungs: Sheets of tissue increase surface area for gas exchange. Sac-like structure attached to a spiracle (opening). • Tracheal tubes: From spiracles, these long, branching tubes extend deep into animal’s tissue. Air is “pumped” through tracheal tubes.

Internal Transport : Dorsal heart. Open circulatory system. Blood collects in empty chambers called sinuses. Defense Mechanisms • Claws • Exoskeleton • Flight • Running • Venomous stingers or bites • Chemical release • Deception/mimicry • Camouflage

Movement: powerful muscles attached to legs, wings, flippers Reproduction: Sexual, internal fertilization. Growth & Development: Molting controlled by hormones. Takes hours/days. Vulnerability.

Metamorphosis: “Dramatic change in form. ” Controlled by hormones. Incomplete metamorphosis: Eggs Nymph Adult. Series of molts required. Complete metamorphosis: Egg Larvae Pupae Adult