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Animals - Protostomes

Animals - Protostomes. Chapter 29. Characteristics of Protostomia:. Based on embryonic development Spiral cell arrangement – early cell divisions are diagonal to the polar axis Determinate cleavage – each cell’s fate is fixed very early Blastophore develops into the mouth.

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Animals - Protostomes

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  1. Animals - Protostomes Chapter 29

  2. Characteristics of Protostomia: • Based on embryonic development • Spiral cell arrangement – early cell divisions are diagonal to the polar axis • Determinate cleavage – each cell’s fate is fixed very early • Blastophore develops into the mouth

  3. Platyhelminthes: Flatworms • The largest group of acoelomate worms • Contain a mesoderm • Have tissues organized into organs • Bilaterally symmetrical • Flat, ribbon-like body • Have a highly branched gastrovascular cavity • Dissolved substances move through the body by diffusion • Most do not have a respiratory or circulatory system

  4. Planaria

  5. Marine Flatworm

  6. Tapeworm

  7. Fluke

  8. Nematodes: Roundworms • Pseudocoelomates – fluid movement acts as a simple circulatory system • Have a one-way digestive tract

  9. Ascaris

  10. Trichinella

  11. Hookworms

  12. Mollusks: Soft-bodied Animals • Snails, slugs, oysters, clams, scallops, octopuses, squid • A larval stage called a trochophore • Second largest phylum of animals • Found in almost all marine, freshwater and land ecosystems • Three major classes: • Gastropods • Bivalves • Cephalopods

  13. Gastropod means ‘stomach-foot’

  14. Bivalve means ‘two-shells’

  15. Cephalopods – ‘head-foot’ squid, chambered nautilus, octopus

  16. Annelids – Segmented Worms • Coelomates • 2/3rds are marine • Each segment contains digestive, excretory, circulatory and locomotor organs and is separated from other segments by septa • Some segments also contain areas responsible for specific functions such as reproduction, feeding or sensation • A primitive brain – the cerebral ganglion – is located at the anterior end, with a nerve cord that runs the length of the body

  17. Marine Tube Worms glue grains of sand together to make their tubes

  18. Marine Feather Duster Tube Worms

  19. Earthworms are hermaphrodites but don’t fertilize their own eggs

  20. Leeches can be useful medicinally

  21. Arthropods – jointed legged animals • All have jointed appendages – legs, antennae, and mouth parts • The largest group of animals – more arthropods than all other groups combined • Divided into two groups: those with jaws and those with fangs or pincers

  22. Three body parts – head, thorax, abdomen

  23. Cephalothorax – combines head and thorax with a separate abdomen

  24. Arthropods must molt their exoskeletons as they grow

  25. Spider fangs

  26. Some arachnids have pincers

  27. Centipedes – 1 pair of legs/segment

  28. Millipedes – 2 pairs of legs/segment

  29. Isopod

  30. Shrimp

  31. Lobster

  32. Crabs

  33. Crayfish

  34. Barnacles

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