Life Cycle of a Snail

A snail is in fact a miniature adult right from birth. The term snail is a common one used to refer to all molluscans that belong to the class Gastropoda. The common characteristics of the class highlight coiled shells. The term snail applies to sea, land and freshwater snails, the epithets referring to the habitat. The ones without shells are called slugs, while those that flaunt broad and conical shaped, but uncoiled shells are called limpets. Snails are known to adapt to various habitats and take on form and behavior accordingly. The subsequent changes in their anatomy make it difficult to draw common assumptions on behavior patterns and physical characteristics.

Snails are found in the sea, ditches, fresh and brackish water, deserts and diverse terrestrial terrain. In comparison with the other varieties, snails that are found in abyssal sea contours are greater in diversity and also biomass. Snails can be herbivorous, carnivorous as well as omnivorous. They move on muscular feet lubricated by mucus. Snails are known to move very slowly, literally at 1mm/s! Snails have a special tissue layer that protects and covers the internal organs. This mantle is attached to the outer shell.

Life Cycle of a Snail

Terrestrial snails produce spermatozoa as well as ova. In the case of freshwater snails and marine species like periwinkles, they display distinctly identifiable sexes. They mate by the time they are a year old. The ritual courtship prior to mating can last for anything between two and ten hours. The snails inseminate each other and fertilize ova. In the case of slugs and land snails, they have a reproductive opening on one side for sperm exchange. Immediately after fertilization, the eggs begin to develop. Hybridizations and Parthenogenesis are not uncommon in snails. There are some snails, especially in the freshwater category that carry the eggs within until they hatch.

The eggs are protected in a warm and damp environment, usually dug a good 10 cm below the top soil. The sizes of the eggs differ according to the species, and range between 3 mm to 6 cm in diameter. The eggs hatch within 4 weeks and the young molluscans emerge. Snails are known to lay eggs at least once a month. The outer shell develops even as the egg fertilizes. Though the embryo has a shell that is weak from the lack of calcium, the formation makes the little ones most distinguishable.

The calcium content for the development of the shell is obtained by eating the egg-shell on emerging. Research reveals that newly hatched snails even cannibalize other, unhatched eggs. At this stage, the snails appear transparent; almost colorless. Thereafter, regular feeding generates the first show of color. At this point in time, the snails looks like miniature versions of the adults. They feed and grow consistently for the next three years and finally attain adult size. The growth process is fast and many even beat their parents with regards to size. Sexual maturity comes in by the time they are one year old.

Different types of snails have different lifespans. In the case of wild Achatinidae, they live for about 7 years, while aquatic apple varieties live barely for a year. Research reveals that they thrive in captivity and even display a lifespan for more than 12 years! Threats to their existence comes in the form of parasites. The molluscans have shells of calcium carbonate that take on a spiral shape. When a snail secretes mucus to build a lip like, thick structure around the shell opening, it is a sign that the growth process has ceased and reproduction is in focus.

Snails have either one or two tentacle pairs on the head. The ommatophores or eye stalks are the upper formations, while the lower tentacle set function as olfactory organs. The tentacles are completely retractable. Snails consume anything from leaves and vegetables to algae, plankton and other microscopic organisms. They succumb to natural predators such as decollate snails, leeches and beetles. The parasitic worm, Leucochloridium paradoxum, affects the retracting of the eye stalk, making the creature vulnerable to birds of prey. Today, environmental pollution and terrestrial encroachment are leading towards the extinction of this beautiful species.