Ward et al. 1997, Nature 390:131-132

1. Red = algae Blue = indigestible particles Bivalves are particle selective (on gills in case of oyster Crassostrea gigas); right shows ciliated tract where particles accepted, left shows ones that are rejected. Ward et al. 1997, Nature 390:131-132

2. Suspension Feeders Sea squirt Styela montereyensis Passive suspension feeding mechanism, combined with active ciliary pump

3. Passive Suspension Feeders - Issues Orientation in current Current velocity - pressure drag Particle concentration - saturation of feeding structure (e.g., polyp processing)

4. Recap - Deposit Feeders and Suspension Feeders • Deposit Feeders - process particles on bottom • Particles range from inorganic (e.g., sand grains) to organic • Organic range from indigestible (cellulose) to very digestible (living digestible bacteria, microalgae) • Quantity important (e.g., bacteria not sufficient as food for most larger deposit feeders) • Selectivity important, digestive strategies important (type of digestion, throughput), recycling of microalgae and external supply of particles important (e.g., deposition after spring phytoplankton bloom to bottom, deposition of seaweed detritus)

5. Recap continued • Suspension feeders - gather particles either passively (protrude structure into current) or actively(suck water into siphon) • Suspension feeders have access different particle qualities - clay, non-living organic matter, microalgae of varying quality (some poisonous some indigestible) • Gathering of particles important, but selectivity also important • Digestive strategies and throughput also important issues • Flow very important - causes change in form

6. Carnivores Polychaete Glycera Oystercatcher Bivalve Cuspidaria Crab Callinectes sapidus Gastropod Nucella

7. Carnivore Issues • Low population size, movement to patches of prey • Capture of prey • Physiological limitations (depth of swimming, sensory biology, intertidal zone) • Feeding, while avoiding predation by other species

9. Conus, over 500 spp. mainly in coral reefs Poison: cysteine-rich peptides - attack ion channels, each species has many different peptides

10. Conus geographus Conus striatus

11. C. striatus C. geographus

12. Diversity of poisonous peptides arise with evolution of multiple gene families, result from gene duplications and later divergence of toxic function

13. Herbivores Polychaete Nereis vexillosa Parrot fish radula Urchins Chiton

14. Herbivore Issues • Ability to mechanically attack plants • Chemical defense of plants • Feeding, while avoiding predation by other species

15. Cellulose Feeder Obtains nitrogen with symbiotic nitrogen fixing bacteria

16. The End