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Animals - Protostomes Chapter 29.

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Presentation on theme: "Animals - Protostomes Chapter 29."— Presentation transcript:

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

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


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