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Arthropods

Arthropods. http://www.iteachbio.com/Marine-Biology/Crustacians.mov. Over 67,000 species Lobsters, crayfishes, shrimp, crabs, water fleas, copepods, barnacles Primarily aquatic Mostly marine but some freshwater Only arthropods with 2 pairs of antennae Mandible 2 pairs of maxillae.

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Arthropods

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  1. Arthropods

  2. http://www.iteachbio.com/Marine-Biology/Crustacians.mov

  3. Over 67,000 species • Lobsters, crayfishes, shrimp, crabs, water fleas, copepods, barnacles • Primarily aquatic • Mostly marine but some freshwater • Only arthropods with 2 pairs of antennae • Mandible • 2 pairs of maxillae Subphylum Crustacea

  4. Lobsters

  5. Crayfish

  6. Shrimp

  7. Shrimp

  8. Crabs

  9. Water Fleas

  10. Water Fleas

  11. Copepods

  12. Copepods

  13. Barnacles

  14. Barnacles

  15. Major tagmata • Head, thorax, abdomen • Carapace • A hard outer covering or shell made of chitin Subphylum Crustacea

  16. Form & Function • Appendages • Swimmerets (abdominal appendages) • Endopod & exopod (inner & outer branches) • Attached to one or more basal segments (protopod) Subphylum Crustacea

  17. General – • Majority are free swimming • Very important components of aquatic ecosystems • Have two pairs of antennae (only arthropods with these) • Most have between 16 and 20 segments • Compound eyes (detects motion) • Crabs & crayfish are on the ends of movable eyestalks Subphylum Crustacea

  18. Ecdysis • (ekdysis = strip off) • Periodic shedding of old cuticle for a larger one • Feeding Habits • Suspension feeders • Plankton, detritus, bacteria • Predators • Larvae, worms, crustaceans, snails, fishes • Scavengers • Dead animals & plant matter Subphylum Crustacea

  19. branchia – gills, podos – foot • Four orders are recognized: • Anostraca – fairy shrimp and brine shrimp • Notostraca – tadpole shrimp (Triops) • Conchostraca – clam shrimp (Lynceus) • Cladocera – water fleas (Daphnia) • Have reduced first antennae and second maxillae • Legs are flattened and leaflike (phyllopodia) • chief respiratory organs Subphylum CrustaceaClass Branchiopoda

  20. include barnacles, copepods, ostracods, and related groups. • Most are small • Most feed by means of their maxillae • Barnacles are an exception • Barnacles feed with thoracic appendages, but in a way that is unique among crustaceans. • basic plan of 5 head and 10 trunk segments • (6 thoracic and usually 4 abdominal) • The abdominal segments typically lack appendages; appendages elsewhere on the body are usually biramous. Subphylum CrustaceaClass Maxillopoda

  21. Subclass Ostracoda • Enclosed in a bivalve carapace (resemble tiny clams; 0.25- 8 mm long) • Fusion of trunk segments; scavenge food, feed on detritus, or collect particles from water • SubclaseCopepoda • Small, elongated, lack carapace and retain simple, median nauplius eye in adults • (kōpē – oar, podos – foot) Subphylum CrustaceaClass Maxillopoda

  22. Ostracoda Copepoda

  23. Subclass Branchiura • Branchia – gills, ura – tail • Primarily fish parasites (despite name, has no gills) • Broad, sheildlike carapace, compound eyes, 4 biramous thoracic appendages & short abdomen • Subclass Cirripedia • Cirrus – curl of hair, pedis – foot • Includes barnacles, as well as smaller orders of burrowing or parasitic forms • Barnacles are sessile as adults • Attach to their substrate by stalk (gooseneck barnacles) • Attach directly (acorn barnacles) • Typically, a carapace (mantle) surrounds their body and secretes a shell • Head is reduced, abdomen is absent, and thoracic legs are long, many-jointed cirri with hairlike setae Subphylum CrustaceaClass Maxillopoda

  24. (malakos – soft, ostrakon – shell) • Largest Crustacae class • Trunk usually has 8 thoracic and 6 abdominal segments • each with a pair of appendages • Many marine &freshwater species • Includes krill, sow bugs, lobsters, crayfish, shrimp, and crabs Subphylum CrustaceaClass Malacostraca

  25. Isopoda (Class Malacostraca) • (isos – equal, podos – foot) • Commonly dorsoventrally flattened, lack a carapace, and have sessile compound eyes • Abdominal appendages bear gills • Common land forms are sow bugs (pill bugs)

  26. Amphipoda(Class Malacostraca) • (amphis – on both sides, podos – foot) • Resemble isopods in that members have no carapace and have sessile compound eyes • However, they are usually compressed laterally and their gills are in the thoracic position

  27. Euphausiacea (Class Malacostraca) • (eu – well, phausi – shining bright, acea – pertaining to) • Group of about 90 species • Important as oceanic plankton known as “krill” • Occur in great oceanic swarms • Eaten by baleen whales and many fish

  28. Krill

  29. Krill

  30. Krill

  31. Whale eating Krill

  32. Decapoda (Class Malacostraca) • (deka– ten, podos– foot) • five pairs of walking legs • First is often modified to form pincers (chelae) • Lobsters, crayfish, shrimp, and crabs

  33. Lobsters

  34. Crayfish

  35. Crabs

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