3rd Year Special Annual Double Issue Vol 4 Issue 1 & 2 Jan - Apr 2 3rd Year Special Annual Double Issue Vol 4 Issue | Page 114

ADVENTURE & WILDLIFE
Interesting Facts About
Snails
A
snail is, in loose terms, a shelled gastropod.
The name is most often applied to land
snails, terrestrial pulmonate gastropod
molluscs. However, the common name snail
is also used for most of the members of the
molluscan class Gastropoda that have a coiled
shell that is large enough for the animal to
retract completely into. When the word “snail”
is used in this most general sense, it includes
not just land snails but also numerous species
of
sea
snails
and
freshwater
snails.
Gastropods that naturally lack a shell, or have
only an internal shell, are mostly called slugs,
and land snails that have only a very small shell
(that they cannot retract into) are often called
semi-slugs.
Snails have considerable human relevance,
including as food items, as pests, as vectors of
disease, and their shells are used as decorative
objects and are incorporated into jewelry. The
snail has also had some cultural significance, and
has been used as a metaphor.
Overview
Snails that respire using a lung belong to the
group Pulmonata. As traditionally defined, the
Pulmonata were found to be polyphyletic in a
molecular study per Jörger et al., dating
from 2010. But snails with gills also form a
polyphyletic group; in other words, snails with
lungs and snails with gills form a number of
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taxonomic groups that are not necessarily
more closely related to each other than they are
related to some other groups.
Both snails that have lungs and snails that have
gills have diversified so widely over geological
time that a few species with gills can be found
on land and numerous species with lungs can be
found in freshwater. Even a few marine species
have lungs.
Snails can be found in a very wide range of
environments, including ditches, deserts, and the
abyssal depths of the sea. Although land snails
may be more familiar to laymen, marine snails
constitute the majority of snail species, and have
much greater diversity and a greater biomass.
Numerous kinds of snail can also be found in fresh
water.
Most snails have thousands of microscopic
tooth-like structures located on a banded
ribbon-like tongue called a radula. The radula
works like a file, ripping food into small pieces.
Many snails are herbivorous, eating plants or
rasping algae from surfaces with their radulae,
though a few land species and many marine
species are omnivores or predatory carnivores.
Snails cannot absorb colored pigments when
eating paper or cardboard so their feces are also
colored.
Vol 4 | Issue 2 |Mar - Apr 2019