Download Higher Invertebrates

Higher Invertebrates
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
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
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
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