What is semi-slug?

We all know snails have shells, and slugs are snails without shells (not exactly). But what are "semi-slugs"? Do they really exist?

Of course they do. Even though semi-slugs are not uncommon, people normally don't notice them due to their size and similarity with slugs.

Semi-slugs are in between of snails and slugs. They are land gastropods whose shells are too small for them to retract into, but not quite vestigial.

We all know snail shells protect them from drying out and predators. Then why are semi-slugs running fast in evolutionary routes to get rid of their shells?

This is because developing a hard thick shell is not easy. It takes a lot energy, nutrition and calcium. It is understandable some snails may sacrifice shells for saving more energy for surviving and mating. Bear in mind evolution is never about individual survival. A lot species would sacrifice individuals for passing down their genes.

Luckily, semi-slugs have learned to adapt their lifestyle to make it up. With smaller shells, they can burrow underground more efficiently, reaching out to food snails can't reach, decrease desiccation and hiding from predators.

Some of you may ask "I heard snail's vital organs are in the shell. Without a shell, where would a semi-slug store their organs?"

That is a very good question. Actually, snail's organs are not in the shell. They are in a place called "mantle". As well as containing many organs, mantle also creates the snail's shell. For a snail, its mantle is covered by the shell. It is completely different for semi-slugs. Semi-slugs mental is unleashed and starts to swallow the shell. So don't worry, semi-slugs still have their vital organs and they are in their mantles.

See what are the differences between snails and slugs?

#semislug #Interestingfactsaboutsnails #snailsintheenvironment