Unio is a type of mollusc that feeds by filtering particles from water. It draws water in through its incurrent siphon using cilia, which beat to transport food like diatoms, protozoa, and detritus towards its mouth. Larger particles are trapped in mucus on its gill surfaces and conveyed to the mantle cavity while smaller particles are moved to the mouth to ingest. This filter feeding process involves the coordinated beating of cilia to efficiently collect and sort food from large volumes of circulating water.

1. FILTER FEEDING
OF MOLLUSCS
Submitted by
A.V.Swathilakshmi
I Msc Zoology

2. UNIO

3. FOOD
O Unio is a planktonic feeder
O Its food consists of diatoms, protozoa,
other micro organisms and organic
detritus brought in by the circulating water
current

4. FEEDING
O Unio displays filter feeding that involves
straining food from large quantities of
water.
O The beating of lateral cilia of the gill
filaments draws water into the infra-
branchial chamber of the mantle cavity
through the inhalent siphon.

5. O The beating of lateral cilia of the gill
filaments draws water into the infra-
branchial chamber of the mantle cavity
through the incurrent siphon.
O The water current enters the gills through
the ostia and egresses to outside through
the excurrent siphon via the
superbranchial chamber of the mantle
cavity

6. O The incoming water contains millions of
microorganisms ,constitute the animal
food.
O The beating of the latero frontal cilia of the
gill filaments towards the outer surface of
the lamallae throws the fine food particles
onto the lamellar surfaces.

7. O The heavier sand particles are conveyed
from the gill surfaces to the edge of the
laminae, which touch the mantle.
O From here these are dropped into the
bottom mantle cavity.
O The lamellar surfaces secrete a mucous
sheet to trap the food particles.

8. O The frontal cilia of the gill filaments beat
downwards towards the food
groove,moving the mucous sheet
downwards.
O The mucus from both side of each gill
lamina moves into the food groove.
O Here,ciliary beating moves the food
towards the mouth.

9.  while reaching in between the labial palps
further sorting of food particles takes place.
 This is achieved by the overlapping folds
on the inner surface of inner surface of the
labial palps.
 In between there will be ciliary tracts beats
outside of the gutter which helps to
separate the heavier particles.
 Another set of the ciliary particles which
helps to move fine particles to the mouth

10. O Through this food passes into the
oesophagus and stomach.
O The heavier particles are accumulated on
the labial palps fling to sweep them to the
mantle cavity
O A sudden thrust of the water outward
through the incurrent siphon carries the
rejected food particles and sediment out of
the mantle cavity.