7 - Feeding (1) Flashcards
Peer
Sites of digestion
- extracorporeally (outside the body)
- intracorporeally (in a gut chamber of some sort)
- intracellularly (within a cell)
Incomplete or blind gut def
Metazoans with only one opening (gut wise) - plathelminths or cnidaria
Feeding modes classifications
- Habitat type: freshwater, sea or land
- What organisms eat: herbivores, carnivores, omnivores, detritivores
- Feeding method: browsing, suspension/filter feeding, deposit feeding, etc
- Food size: microphages (feeding on very small organisms) versus macrophages
- Food location within the environment: water column, benthic substratum, etc.
Types of feeding
- Browsers
- Suspension feeders
- Deposit feeders
- Active feeders
- Biters, chewers, suckers
Predator classification
- Motile stalkers
- Lurking (ambush) predators
- Grazing carnivores
- Cannibalism
Primary mechanisms for removing food particles
- Setose appendages
- Mucous-bag feeding
- Ciliary mechanisms
- Tentacle of tube feet suspension feeding
Browsers def
Have rasping radula (ribbon-like structure/ belt-like rasp armed with chitinous teeth) that removes layer of encrusting organisms from rocks
All mollusks except BIVALVES
Suspension feeders def
- They remove suspended food particles (floating or drifting) in water by capture, trapping or filtration mechanism
- Particles can be large and visible or microscopic
Suspension feeders eg.
- Sponges
- Ascidians
- Brachiopods
- Bivalves
- Many crustaceans
- Polychaetes
- Gastropods
3 steps in suspension feeding
- transport of water past the feeding structures
- removal of particles from the water
- transport of the particles to the mouth
Which type of lifestyle have efficient filtering mechanisms? (Suspension)
Sedentary lifestyle
Passive food collection def (suspension)
Spend little energy to get water in, but lots of energy to capture food (stinging cells)
Passive suspension strategy
Optimal positioning in the environment where they can use the water flow (Cnidarians)
Strategies to capture food particles (Suspension)
- Move part of/whole body through water (active)
- Water moved over feeding structures (passive)
3.Facultative mode or combination of both above
Main food selection criteria in suspension feeders?
Particle size
Active food collection def (suspension)
Spend lots of energy to transport water over filtration energy
Mucous- bag feeding def
- Nets or bags of mucus are spun from the mouth
- When trap is full, both the mucus and the prey are eaten
- The net can be filled by water flow provided by muscular means or natural currents
Active suspension strategy
Alter the flow, filter large amounts of water (bivalves)
Setose appendages def
Coarse particles are trapped and moved to mouth (larger planktonic & benthic crustaceans)
Ciliary mechnaisms def
- Numerous slender filaments
- Particles can be trapped by mucus or not
- The beats of the cilia produce a current and can direct the stream of trapped particles
- Sorting on basis of both particle size and chemosensing (freshwater Bryozoan)
Tentacle or tube feet suspension feeding def
Tentacle-like structures capture food particles, with or without mucus (Echinoderms (e.g. brittle stars and crinoids) & cnidarians (certain sea anemones and corals))
Deposit feeders def
- Obtain nutrients from sediments of soft-bottom habitat (mud/ sand) or terrestrial soil
Types of deposit feeders
- Direct deposit feeder
- Selective deposit feeder
Direct deposit feeders def
Swallow large amounts of sediment - polychaete annelids
- some snails
- sea urchins
- most earthworms
