You'll have to forgive my continuing fascination with these critters.
I read on an apple snail forum about a feeding strategy that some snails use called skim feeding. The snail climbs to the water surface and forms a saucer-shaped structure with its foot that acts as a skimmer. The snail pumps water into the saucer, drawing nearby floating food particles within the mouth's reach.
This is the first time I observed this behavior in my snails. Obviously, they are no
longer content to settle for algae
wafers and whatever flake food happens to make its way to the bottom- they want the big choice flakes that the fish always get to first!
The first pic is taken from above. You can see the ring of surface tension around the saucer's edge and a morsel of food being drawn into it.
The second pic is taken from the side. The snail uses the rear half of the foot to anchor itself to the glass and the front half to form the saucer.
Third and fourth pics are taken from above. The snail traps and gulps down a big piece of flake. Yum!