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UNIT 7

UNIT 7. INVERTEBRATES PART 2. ARTHROPODS. ARTHROPOD CHARACTERISTICS. Largest phylum of animals Most marine arthropods are crustaceans Body is segmented, bilaterally symmetrical Jointed appendages Exoskeleton made of chitin Molt (shed exoskeleton) small. CRUSTACEANS.

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UNIT 7

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  1. UNIT 7 INVERTEBRATES PART 2

  2. ARTHROPODS

  3. ARTHROPOD CHARACTERISTICS • Largest phylum of animals • Most marine arthropods are crustaceans • Body is segmented, bilaterally symmetrical • Jointed appendages • Exoskeleton made of chitin • Molt (shed exoskeleton) • small

  4. CRUSTACEANS • 68,000 known species • Most marine • Have gills • 2 pairs of antennae • Examples; copepods, barnacles, amphipods, isopods, krill, shrimp, lobster, crabs

  5. BIOLOGY OF CRUSTACEANS • Filter feeding • smaller crustaceans • Use bristles on appendages to gather particles • Use appendages in some for sucking and piercing • Stomach has chitinous teeth • Predators- decapods • Stomach is two chambered; digestive enzymes • Extracellular digestion; have anus

  6. Open circulatory system • Gill exchange gases • Simple brain; but well developed sensory organs • Compound eyes • Keen sense of smell • Communicate with signals

  7. REPRODUCTION & LIFE HISTORY • Separate sexes • Internal fertilization • In decapods, females carry their eggs in their pleopods or swimmerets • Most have planktonic larvae

  8. SMALL CRUSTACEANS • COPEPODS: planktonic; use mouthparts to filter and capture food • Some parasitic

  9. Barnacles- filter feeder; live attached to surfaces; body enclosed with heavy calcareous plates; have feathery filtering appendages called cirri

  10. Beach hopper • AMPHIPODS- have a curved body that is flattened sideways • Under ¾ in • Head and tail typically curve downward • Ex: whale lice, beach hoppers • 5000 species

  11. Right whale with whale lice Whale lice

  12. Fish lice • ISOPODS- similar in size to amphipods but have legs that are similar to each other and the body is dorsoventrally flat (flat back) • Pill bugs (land) • Fish lice

  13. Giant deep sea isopod

  14. KRILL OR EUPHAUSIIDS- shrimp-like crustaceans; up to 2.5”; planktonic; head is fused with some of the body segments to form a carapace • Most filter feeders • Polar waters • Deep water • Main food source for large marine mammals

  15. krill

  16. School of krill

  17. DECAPODS • Shrimps, lobsters, and crabs • 10000 species • Largest group of crustaceans • Five pairs of legs or perapods • 1st which is the heavier- the claw or cheliped • 3 pairs of maxillipeds- close to the mouth; used for eating • Well-developed carapace and encloses the cephlathorax (fused head and thorax) • abdomen

  18. Shrimps and lobsters • Laterally compressed bodies with elongated abdomens • Shrimps are scavangers-some are cleaners • Some burrow in muddy bottoms • Lobsters are mostly nocturnal; scavangers and predators; • Hermit crabs (they are not true crabs) are scavangers; hide in snail shells

  19. Mantis shrimp Giant lobster

  20. Hermit crab

  21. OTHER MARINE ARTHROPODS • HORSESHOE CRABS • 5 living species • Last of the class Merostomata; “living fossils” • Live on soft bottoms in shallow water • 5 pairs of legs

  22. SEA SPIDERS • 4 or more pairs of jointed legs w/small body • Large proboscis w/mouth at the tip used to feed on small invertebrates • Cold water

  23. Insects • 3 prs of legs as an adult • Rare in the sea • Most live on water’s edge or high tide mark • Marine water strider

  24. LOPHOPORATES BRYOZOANS, PHORONOIDS, LAMP SHELLS

  25. LOPHOPHORATE CHARACTERISTICS • 3 groups • Have a unique feeding structure called the lophophorate which is a set of ciliated tentacles arranged in a horseshoe shape • Suspension feeders • No segmentation • Bilateral symmetry • U-shaped gut

  26. BRYOZOANS- form colonies on seaweeds, rocks and other species • 4500 species; almost all marine • In phylum Ectoprocta • Colonies of individuals called ZOOIDS that secrete skeletons of various shapes • Lopophore is retractable • U-shaped gut ends in an anus outside the edge of the lophophore

  27. PHORONOIDS-worm-like and build tubes • Horseshoe-shaped or circular lophopore • 20 species • Burrow in sand or attach tubes to hard surfaces • Very small

  28. LAMP SHELLS OR BRACHIOPODS • 350 SPECIES • Shell w/2 valves that are dorsal and ventral to the body • Have a lophophore- w/2 ciliated and coiled arms • Attached to rocks or burrowed in soft sediment

  29. ARROW WORMS CHAETOGNATHS

  30. Characteristics of Arrow worms • About 100 species • Transparent; streamlined; fish-like fins and tail • Head has eyes, grasping spines and teeth • Up to 4” • carnivores

  31. Arrow worm

  32. ECHINODERMS 5-WAY SYMMETRY “spiny-skinned” movie

  33. ECHINODERM CHARACTERISTICS • Radially symmetrical-adults • Pentamerous – based on 5-parts • Bilaterally symmetrical- planktonic larvae • No head • No anterior/posterior end; no ventral/dorsal side • Refer to the oral and aboral side • Complete digestive tract • Well-developed coelom

  34. Endoskeleton • Water-vascular system- waterfilled canals • Tube feet- muscular extensions of canals • Extended when filled with water- have muscular sacs called ampullae • Used for movement, attachment, and receiving chemical and mechanical stimuli • Madeporite- or sieve plate- in sea stars and sea urchins; on the aboral side; where water enters the water vascular system

  35. BIOLOGY OF ECHINODERMS • Radial symmetry = sedentary life style • Feeding and digestion- sea stars are carnivorous; they extend their stomach out through their mouth and excrete digestive enzymes; the food is then carried into the digestive gland and the stomach moves back into the body; if intestines are present, they are very small • Brittle stars- no anus; very simple guts • Crinoids- simple guts

  36. Feeding and digestion cont. • Sea urchins and sea cucumbers have long coiled guts (sea urchins need this because they are herbivores and the sea cucumbers need this because they need to process sediment) • In all echinoderms, nutrients are passed in the coelomic fluid within the coelom • Also transports oxygen because they don’t have a circulatory system • Sea cucumbers have respiratory trees- which are thin, branched tubes that are connected to the gut and extend out to the anus

  37. NERVOUS SYSTEM AND BEHAVIOR- have a nerve net- more complex actions than cnidarians though • REPRODUCTION AND LIFE HISTORY- • Separate sexes • External fertilization • Zygote develops into a ciliated larva • Some don’t have larva but brood their offspring in specialized pouches • Some reproduce asexually by the separation of the central disc or body into two pieces- REGENERATION

  38. TYPES OF ECHINODERMS • 7000 KNOWN SPECIES- all marine • Bottom dwellers • 1. Class Asteroidea= sea stars • 5 arms that radiate from central disk • Amulacral groove= the radiating channels on the arms • Can move in any direction • Endoskeleton = interconnected plates of calcium carbonate creating very flexible arms; aboral surface may be covered with spines that are modified into pincer like organs called pedicellariae which helps to keep the surface clean

  39. Asteroidea cont. • Most are predators of bivalves, snails, barnacles or other attached or slow moving animals • Class Ophiuroidea= brittle stars; 5 arms are very long and brittle • Most eat detritus and small animals • Tube feet don’t have suckers, used for feeding • No anus • Most species (2000)

  40. Indian Sea Star Anthenea crassa

  41. Choriaster granulatus , the dough-boy star Sunflower Sea Star

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