1. I. I.Arthropoda B. B.Crustacea 1. 1.Decapoda (order) Crabs, true shrimp, lobsters Most species in Crustacea (~10,000) Scavengers/Predators/Both Five pairs of walking legs First pair usually modified as claws for feeding/defense Well-developed carapace = cephalothorax Rest of body = abdomen Lobsters, shrimp – Usually laterally compressed Tail/Abdomen behind thorax Crabs – Usually dorsoventrally compressed Tail/Abdomen curled underneath thorax Largest crustaceans Lobster > 42 lbs Crab > 13 feet “tall”

3. Decorator crab Hermit crab

4. I. I.Arthropoda B. B.Crustacea 1. 1.Decapoda (order) Crabs, true shrimp, lobsters Most species in Crustacea (~10,000) Scavengers/Predators/Both Five pairs of walking legs First pair usually modified as claws for feeding/defense Well-developed carapace = cephalothorax Rest of body = abdomen Lobsters, shrimp – Usually laterally compressed Tail/Abdomen behind thorax Crabs – Usually dorsoventrally compressed Tail/Abdomen curled underneath thorax Largest crustaceans Lobster > 42 lbs Crab > 13 feet “tall”

5. Fig. 9-35

8. I. I.Arthropoda B. B.Crustacea 1. 1.Decapoda (order) Diverse nutritional modes: predators (Ex: lobsters), deposit feeders (Ex: fiddler crabs), suspension feeders (Ex: mole crabs) Dioecious May exhibit courtship behavior, territoriality Males often transfer spermatophores to female with modified copulatory pleopods Fertilization usually internal Eggs usually brooded Larvae pelagic Nauplius – shrimp, other crustaceans Zoea – crabs

10. Nauplius Zoea Fig. 9-36 Megalopa

11. I. I.Arthropoda B. B.Crustacea 2. 2.Copepoda Extremely abundant and important plankton Among most abundant animals on earth Benthic forms also important Important primary consumers of phytoplankton Many exhibit DVM Some parasitic forms

12. Harpacticoid copepods Parasitic copepods

14. Herbivorous vs. Predatory Copepod

15. I. I.Arthropoda B. B.Crustacea 3. 3.Euphausiacea (krill) Laterally compressed Up to 10 cm long (usually smaller) Head and anterior segments fused to form distinct carapace Widespread distribution Important primary consumers and predators Important prey for larger consumers Keystone species in some ecosystems (Southern Ocean) Aggregate in schools May be immense (450 sq km x 200 m @ >1000 m -3 ) May molt rapidly; predator avoidance?

18. I. I.Arthropoda B. B.Crustacea 4. 4.Amphipoda Laterally compressed Generally small (< 2 cm), but larger in deep ocean Widespread distribution Generally free living Important scavengers Often highly mobile Some sedentary forms Diverse lifestyles Brood young

23. I. I.Arthropoda B. B.Crustacea 6. 6.Isopoda Dorsoventrally compressedDorsoventrally compressed Generally small (< 2 cm), but larger in deep oceanGenerally small (< 2 cm), but larger in deep ocean Related to terrestrial pill bugsRelated to terrestrial pill bugs Widespread distributionWidespread distribution Generally free livingGenerally free living Important scavengersImportant scavengers Often highly mobileOften highly mobile Some parasitic formsSome parasitic forms Brood youngBrood young

26. I. I.Arthropoda B. B.Crustacea 6. 6.Cirripedia (barnacles) Active suspension feeders (filter feeders) Use feathery cirripeds (modified swimming appendages) Sessile (attached to surfaces) Fouling organisms (boats, hard surfaces, whales) Resemble mollusks superficially Some parasitic forms Simultaneous hermaphrodites Internal fertilization (How??)

28. Fig. 9-41 StalkedSessile

30. I. I.Arthropoda B. B.Crustacea 6. 6.Cirripedia (barnacles) Active suspension feeders (filter feeders) Use feathery cirripeds (modified swimming appendages) Sessile (attached to surfaces) Fouling organisms (boats, hard surfaces, whales) Resemble mollusks superficially Some parasitic forms Simultaneous hermaphrodites Internal fertilization (How??)

32. I. I.Arthropoda B. B.Crustacea 7. 7.Stomatopoda (mantis shrimp) Specialized predators Modified second pair of thoracic appendages Smashers (eat mollusks, crabs) Video VideoVideo Spearers (eat shrimp, fishes) Sophisticated eyes Three lobes (midband for color vision) Up to 16 photoreceptor types (humans have four) Can see ultraviolet & polarized light Reproduction Female lays egg mass Zoea larvae in plankton up to three months