Marine Ecology, April 18, 2007

1. Marine Ecology, April 18, 2007 Invertebrates 3: Phylum Arthropoda

2. Phylum Arthropoda • Major arthropod features • Body segementation/specialization of regions • Paired, jointed appendages • Exoskeleton • Several non-living layers of cuticle, secreted by the epidermis • Contains chitin • Cuticle also forms mouthpart structures, lining of digestive tract, eye lens, and wings.

3. Phylum ArthropodaSubphylum Crustacea features • Two pair of antennae, followed by three pairs of mouthparts • Compound eyes, sometimes on stalks • Head and thorax often combined into a "cephalothorax“ • Appendages • Biramous (double-branched) appendages • Not apparent in many crustaceans • Often have calcium carbonate in cuticle (“crustose”) • Many have gills. • In common crustaceans, attached to base of legs, extend up into thorax.

4. Other concepts/terms • Thoracic appendages often are walking legs or modified for food handling • Abdominal appendages sometimes modified as "pleopods", broad swimming appendages. • Very end of abdomen often formed by two types of structures; can see these clearly in shrimp. • Telson • Uropods

5. Order Amphipoda(Beach hopper)

6. Order Isopoda Idotea sp. Ligia pallasii

7. Order Decapoda • Carapace completely covers head and thorax • Eight pairs of thoracic appendages • 3 as modified mouthparts (maxillopeds) • 5 pairs as walking legs

8. Order Decapoda Petrolisthes cinctipes Pagurus sp. Pachychelis rudis *Add me to your list!

9. Shore crabs Hemigrapsus nudus Pachygrapsus crassipes Hemigrapsus oregonensis

10. Cancer sp. crabs C. antennarius C. productus C. magister C. oregonensis

11. Pugettia producta: kelp crab

12. Order Cirripedia: the barnacles Balanus sp. Pollicipes polymerus Chthamalus sp.