Water Snails

Snails come in all shapes and sizes.  Some come as bird food.  Earlier this week I saw a magpie fly down to the plot, pick up a snail and proceed to bash it on our shed roof.  

Some, in company with the slugs and the caterpillars, colonise our cabbages.

And some live in the water tanks.  Once in another hot summer, I saw the water level had fallen through repeated watering and little black pointy objects were adhering to the sides of the tank.  I peered more closely at them.  They were water snails.

I have no inkling of how they got into that bare environment.  It must be a boring life to be a snail in a water tank creeping up and down the sheer sides on one muscular foot, scraping up microscopic algae with a raspy tongue. I wondered, do they ever suffer from a snail population explosion?  It seems not, as numbers to my random eye appear constant.  Do they have any predators?  Probably not.  Our tanks, filled from the mains, never host anything else larger than midge larvae and the odd pond skater - another mystery visitor. 

Once, and let me use the passive voice, tropical land snails were found on our allotment.  They were captured and confined to a jam jar before being donated to a local school.  They were not small.  It is better that they occupy a large glass tank in a classroom with scope for labels, drawings and creative writing. 

Meanwhile, under the equilibrium that we currently enjoy, the magpies and other predators will peck at snails, conscientious humans like ourselves will scatter barrier pellets to deter them and in their tanks the water snails keep climbing, or stick fast, retreat into their shells and wait for the water to rise.