3. Sea squirts: Urochordata related to amphioxus and cephalochordata Diagram by Woods Hole Oceanographic Institution Hole

5. Filter feeding in annelids: sabellid worms

7. Arenicola : lugworm Polychaete Annelida Tail toward head shaft Ingests sand rich in micro- organisms and plankton left by receding tide Every 40 min castings of sand Tide in: stream of water driven through burrow tail to head direction current gas exchange sweeps away carbon dioxide and nitrogen; body swellings

9. Commatulid grasping coral head on reef

10. Commatulidae: feather stars podia originate as filter feeding devices

11. Swimming in commatulids

13. Mole crab

16. Whale shark

17. Blue whale; baleen

18. krill