Filter FeedingIn PolychetesIn MolluscsIn DeuterosmiaIn Crustaceans

RespirationPhysical factorsPigmentsGills and Lophophores in PolychetesGills and Lungs in MolluscsGills and Trachea in Arthropods

SyllabusSyllabus

Filter FeedingFilter FeedingThis type is found only in aquatic

animalsIt is disappeared from the terrestrial

animals due to the lower density of airIt is occurred in small aquatic animals It takes place through special organs

Filter Feeding in PolychetesFilter Feeding in PolychetesThe simple and good examples occur

among the polychaetes

These worms are free-moving Macrophagous and microphagousMost have an eversible pharynxPharynx is used for burrowing and feeding

Filter Feeding in PolychetesFilter Feeding in Polychetes The simple and good example occur in Nereis

It produces over its body surface a mucous secretion into a net which protects the surface and forms temporary linings to burrows .

Water can pumped through this net. Food particles collect in the mucus secretion in the bag and

is swallowed This feeding mechanism have been aided by the presence of

head tentacles and palps

Filter Feeding in PolychetesFilter Feeding in PolychetesThe previous structure has given rise in

sedentary worms to tentacular outgrowths (gills or branchial crowns)

These structures use in respiration but they also use in mechanisms for the collection and sorting of food particles.

These structures also produce mucus which distributed over the ciliated surfaces

This feeding mechanism have been aided by the presence of head tentacles and palps

The second example occurs in Terebellid wormsCiliary feeding mechanisms occur in the

sedentary polychaetesThese worms live in permanent tubes in

mudFood particles enter the mouth opening by

Extending the long ciliated tentacles from the head over the surface of the substratum

Food is trapped in mucus and swept along ciliated grooves into the mouth

Filter Feeding in PolychetesFilter Feeding in Polychetes

Filter Feeding in PolychetesFilter Feeding in PolychetesThe second example occurs in Terebellid

wormsTentacles are highly mobileThey vary at different pointesAt one point a tentacle will be flattened to

form a zone of attachment Distal of this point the remainder of the

tentacle explores the substratumProximal the attachment point, the surface

of the tentacle will be folded to form a ciliated groove in which the food is propelled.

Terebellid worms

Filter Feeding in PolychetesFilter Feeding in PolychetesThe third example occurs in Chaetopterus

This worm lives in sand or mud a U-shaped tube There is no branchial crown There are three pairs of fans that are modified

parapodia Water is drawn through the tube by the beating of

these fans There is another pair of outgrowths forms two

wings in front of the fans They are pressed against the wall of the tube They secrete mucus Mucus is drawn backwards by cilia in a ventral groove

to a conical bag There is a small cup surrounded the conical bag

Food particles are strained out by this mucous bag Food particles are rolled up into a pellet in the cup

At intervals the secretory process stops and the cilia in the ventral groove move in reverse

Therefore the pellet of food is transported from the cup to the mouth and swallowed.

Filter Feeding in PolychetesFilter Feeding in Polychetes