Higher Invertebrates

1
Higher Invertebrates
2
F. Phylum Mollusca

• 2nd largest animal phylum
• (over 100,000 species) snails, slugs, octopus,
  clams
• soft-bodied
• have shells (internal or external) in most
• 3 body regions
• head
• foot
• visceral mass
• classified by foot and shell

3
Phylum Mollusca

• body surrounded by mantle, which secretes the
  shell
• complete digestive system
• mouth contains specialized feeding organ
• called a radula in some
• circulatory system is open blood is not
• confined to vessels
• reproduction is exclusively sexual
• respiration by gills or through moist skin

4
G. Phylum Arthropoda(means jointed foot)

• -characteristics
• 1) exoskeleton of chitin
• 2) jointed appendages
• 3)segmented bodies
• -bilateral symmetry
• -complete digestive system
• -open circulatory system
• -dorsal heart, ventral nervous system
• -molting shedding exoskeleton required for
  growth

5
Phylum Arthropoda

• Body segments
• head, thorax, abdomen (as in insects)
• cephalothorax (fused head thorax),
• abdomen (as in arachnids)
• head, trunk (fused thorax abdomen)
• (as in centipedes)
• examples spiders, ants, crayfish, centipedes