Phylum Arthopoda (Greek for “jointed foot”) Taylor Myers, Stephanie Gillespie, Tony Bent

Drill Have you ever seen a: Spider Lobster Crab Insect Describe these animals and what makes them unique.

Vocabulary Appendage-Projecting part of an organism, with a distinct appearance or function. Chitlin- A substance made of polysaccharides that forms the majority of an exoskeleton. Spiracle- An external respiratory opening. Exoskelton- A rigid external covering for the body.

Characteristics More than 83% of all animal species are arthropods. All arthropods have exoskeletons made of chitlin. Classified by habitat, body structure, diet. Have an open circulatory system.

Characteristics continued… More evolved than their ancestors: -Bilateral symmetry(left-right) -Segmented body -Hard exoskeleton -Jointed legs -Many pairs of legs NO backbone

Crustaceans Two pairs of antennae Branched appendages Legs attached to abdomen 30,000 species Lobsters Crayfish Crabs Barnacles Shrimp Most members of this class are marine animals. Breathe through gills Shrimp, crayfish and lobster have specialized swimming structures

Chelicerata Ancient group-includes extinct animals. Eight legs Pinchers and fangs No mandible (jawbone) No antennae Haemocoelic cavity(part of circulatory system) Horseshoe crabs Scorpions Spiders Mites

Uniramians One pair of antennae Bilaterally symmetrical Segmented and jointed legs Tracheal system(series of tubes that carry oxygen to cells in an insect’s body) Most live on land Butterflies Beetles Millipedes/centipedes

Evolution Arrived on Earth during the Cambrian period. Invaded new geographic areas and habitats over time as they evolved (new niches). Still evolving after 500 million years. Over 2 million types in the world.

Evolution continued… Theoretically evolved from annelids(segmented worms). Related to the trilobites-died out 248 million years ago, almost extinct today. Most successful animal Phylum on the planet (population, size, species diversity).

Molting A process in which animals shed their exoskeleton and inflate their body before the new skeleton hardens. Occurs periodically. The animal must shed (molt), and animals must then rapidly grow and produce a new, larger exoskeleton to grow into.

Molting continued… During molts, animals are extremely vulnerable. Arthropods must molt to grow.

Wrap-up What have you learned about arthropods?