It's a slug's life

Or maybe not ... slug eyes come in the form of eyespots at the end of retractable optical tentacles. Though they can't define color or shape, they are light-sensitive, can grow back if damaged, and have the multi-tasking ability to detect smell. Useful, given that only 5 percent of the vast slug population is above ground at any one time.

Slugs are hermaphrodites who mate by encircling each other and exchanging sperm. In some species, such as the bright yellow banana slug, the penis - which can be as long as six inches - can become trapped inside the body of the partner. This unfortunate dilemma is resolved through apophallation, a practice in which either the partner or the owner of the lodged member chews it clean off.

Days after mating, a slug will lay somewhere between 20 and 100 eggs in the earth, where they can remain dormant for many years waiting for the ideal conditions to hatch. Because they lay eggs several times each year, it has been estimated that a single slug can grandparent as many as 90,000 offspring. But since they don't live in groups, they may never know their ma or pa.

Originally creatures of the sea, slugs require moisture. And lots of it. Their ideal habitat is the damp darkness of hedgerows, compost heaps or rotting wood. If during warm weather nothing suitable is to be found, these innovative little survivors are able to house themselves in a papery structure that resemble a cocoon, affixing it to a wall or a tree until the heat passes.

For all their evolutionary refinement, slugs are loathed by gardeners and farmers, who avidly share tips on whether salt, beer or toxic pellets are the best way to get kill them. Though they regularly fall victim to all methods on the market, slugs continue to slide through the world in abundance. It is estimated that a cubic meter of moist garden will accommodate as many as 200 of the creatures.

Slugs are not fussy about what they eat, and will content themselves with pretty much anything digestible they come across on their slippery travels. That includes plants, compost, fungi and in some cases, carrion or disposed cat food. If you were under the impression that slugs are toothless beings, it is time to disappoint. They have as many as 27,000 teeth - even more than sharks.

Slugs move by contracting muscles on their underside, and by secreting a mucus than enables them to slide along. They defend themselves against predators such as hedgehogs, snakes, toads and birds by tightening to become round and hard, at the same time firmly attaching themselves to their surface. When the coast is clear, they can also stretch to several times their normal length.

Okay, so we humans find slug slime pretty gross - but for the creatures that produce it, it is their lifeline. Not only does it help them get around, it also protects their skin against sharp edges such as razor-sharp pieces of glass. Pretty innovative. Slug slime is also water resistant, which makes it hard to remove. So the slug gets the last laugh.