Mollusks and Annelid Worms

1. Mollusks and Annelid Worms Ms. Youngblood

2. Mollusks and Annelid Worms • Have a coelom and a circulatory system. • More-complex nervous systems than those of flatworms and roundworms

3. Mollusks • Phylum Mollusca: includes snails, slugs, clams, oysters, squids, and octopuses. • 2nd largest phylum of animals

4. Three Classes of Mollusks • Gastropods: Snails and Slugs • Bivalves: Clams and other two-shelled shellfish • Cephalopods: Squids and octopuses

5. Mollusks • Most live in the ocean, but some live in fresh water habitats. • Few (like slugs and snails) have adapted to life on land. • 1mm long snails to the giant squid which can range up to 18 m in length. • Most move slowly.

6. Body Parts of Mollusks • Foot – used for movement, in Gastropods it secretes mucus. • Visceral mass – contains the gills, gut and other organ. Contained in the coelom • Mantle – protects the visceral mass • Shell – most mollusks have a shell that protects the mollusk from predators

8. How do Mollusks eat? • Clams and other bivalves filter particles from the area around them • Snails and slugs eat with a ribbonlike tongue covered with curved teeth. (Radula) • Can also be parasitic • Octopuses and squids use tentacles to grab their prey and place it in their powerful jaws.

9. Closed vs. Open Circulatory System • Open Circulatory System • Simple heart pumps blood through blood vessels that empty into spaces in the animals body called sinuses. • Most mollusks have an Open Circulatory System • Closed Circulatory System • A heart circulates blood through a network of blood vessels that form a closed loop • Squids and octopuses have a closed circulatory system that is much simpler than ours.

10. It’s a Brain • Mollusks have complex ganglia • These ganglia control breathing, move the foot, and control digestion • Cephalopods have a more complex nervous system than any other mollusks • In fact the have the most complex of any invertebrates • They have a brain where all of their ganglia are connected • They can learn!

11. Annelid Worms • Segmented worms • Segments are identical or almost identical repeating body parts • More complex than flatworms and roundworms • Have a coelom and a closed circulatory system • - have a brain in their head and a nerve cord that connects the brain and the ganglia

12. Kinds of Annelid Worms • Three classes: Earthworms, Bristle worms, and leeches • Can live on salt water, fresh water, or on land. • They may scavenge, or they may prey on other organisms as parasites or predators.

13. More than just bait • Earthworms are the most common • They have 100-175 segments, most of which are identical • Some segments are specialized for eating and reproduction • Earthworms have stiff bristles which help them move

14. Bristles can be beautiful • Bristle worms come in many varieties and colors. • All Bristle worms live in water

15. Blood Suckers and More • Not all leeches suck blood • Others are scavengers that eat dead organisms • Others are predators that prey on insects, slugs and snails • Medicinal uses