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

4. 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

5. Planaria

6. Marine Flatworm

7. Tapeworm

8. Fluke

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

10. Ascaris

11. Trichinella

12. Hookworms

13. 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

14. Gastropod means ‘stomach-foot’

15. Bivalve means ‘two-shells’

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

17. 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

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

19. Marine Feather Duster Tube Worms

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

21. Leeches can be useful medicinally

22. 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

23. Three body parts – head, thorax, abdomen

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

25. Arthropods must molt their exoskeletons as they grow

26. Spider fangs

27. Some arachnids have pincers

28. Centipedes – 1 pair of legs/segment

29. Millipedes – 2 pairs of legs/segment

30. Isopod

31. Shrimp

32. Lobster

33. Crabs

34. Crayfish

35. Barnacles