By Conservancy Education intern Emily Colombo
When exploring the Dalton Discovery Center here at the Conservancy of Southwest Florida, one of the most popular attractions is the Touch Tank. Several of the resident animals are quite memorable and noticeable without much explanation; however, some of our other denizens are often left underappreciated by guests. One of these is a collective group that actually makes up the majority of the population of the exhibit: gastropods!
Gastropods are a class of mollusks and they represent 80 percent of the mollusk phylum (Myers & Burch, 2001). Snails and slugs fall into this category, and they are extremely widespread, occurring in every ocean and on every continent except for Antarctica!
Gastropod anatomy follows a general body plan, with variations that have allowed them to adapt to almost every ecosystem on Earth. Through their natural history, several groups have lost one of the main characteristics of a gastropod: a univalve shell.
Shells come in all shapes and sizes, and the animal makes its shell larger as its body grows by secreting different protein/mineral complexes through the mantle, (the membrane that lines the inside of the shell) Most gastropods also have a tongue-like appendage that is used for eating that is called a radula.
Radulas are covered in small chitinous teeth, similar to a cheese grater, and can be highly specialized to fulfill specific needs. For example, many people keep freshwater snails in aquariums because they use their radula to scrape algae off of the glass and decor. Others use their radula paired with an acid to bore through shells of bivalves, like clams, to eat them.
In order to use this radula, however, gastropods have to be able to move around, which they do by using a very muscular “foot.” Fused to the top of the foot is aa structure called the “operculum.” It is positioned in such a way that when the animal twists and rotates back inside its shell for protection, the operculum fits over the opening in the shell, effectively sealing off the vulnerable body from predators.
Next time you visit the Touch Tank, look around for our multiple gastropods, and remember that even though they are slow, they are a very interesting set of animals!