because...... if they are gone, so are sparrows and so are hawks and so on. Just like sunlight, or plants, we need them too
because
it has a shell
They eat the algae all around the pond.
For what? This is a poor question. Moss is not an important food source for a lion. Moss might be an important food source for snails.
Slowly, very slowly. In reality, snails don't migrate. They're too slow to be able to travel any important distances. If needed, many snails have methods to hibernate if it gets too dry or if food runs low.
Apple snails are freshwater aquatic snails. Garden snails are land snails.Apple snails have lungs and gillsGarden snails have lungs onlyApple snails skin is thin and translucent (with slime)Garden snails skin is thick and leathery (with slime)All apple snails have two sets of antennaeGarden snails have species with one and two sets.
water snails but not regular snails
Sea snails Freshwater snails
Apple Snails will eat other snails if you don't feed them. If you feed them, then they are alright.
Snails do not have bristles. Snails do have a raspy tongue though.
no snails are not harmful.
Snails are invertebrates. :)