Feeding and nutrition

deposit feeding

eat sediments and ingest the microorganisms, POM, and dissolved nutrients in it

how is form related to function?

the shape of a body part influences its function, e.g. a siphon in a mussel is shaped to suck water in and push it out

selective deposit feeding

sort the sediment

nonselective deposit feeding

don’t sort the sediment, requires specialization

deposit feeding species

arenicola, worms, molluscs

bolus

mucus-bound package of food that gets passed to the mouth via cilia

ciliary/mucocilliary deposit feeders

some specialization in gut: acid in gut lumen to strip particles from mucus, alkaline intestines to reconstitute mucus

deposit stripping

detritus is nutrient poor so it has to be decayed or fragmented by microbes

why does detritus have to be processed by microbes?

most invertebrates don’t have cellulases to break down the cellulose in particulate organic matter

suspension feeding

trap or sieve suspended particles from the water

passive suspension feeding

use the natural water currents to get food into mouth

active suspension feeding

creating a water current towards the mouth, e.g. via ciliary action

types of suspension feeders

phytoplankton, zooplankton, sponges

reynold’s number

Re = inertial forces / viscous forces

what happens when there is a small Re?

viscous forces are stronger → lack of inertia → passive feeding isn’t effective

lamellibranch gills

filaments create a water current → food gets trapped on gills and moved along food groove to the palps

labial palps function

selectively sort food

how is rejected food ejected in bivalves?

as pseudofeces via the inhalent siphon

setose filtration

traps food on setae and brings it to the mouth

cirriped feeding

cirri grab particles from the water and bring it to the mouth

gastropod grazing

use radula to rasp rocks

subradular membrane

moves everything so the ‘teeth’ are extended outward to rasp

urchin grazing

5 calcareous plates with teeth that are extended by muscles to bite

ram feeding

large mouth- fish overtakes food with open mouth or opercula

inertial suction

small mouth- rapid mouth opening and buccal floor expansion draws food inward

mandibulation

jaw behavior like biting or rasping

true/false: the inhalent gill on bivalves has fringed edges

true