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Home › Sea Life › Aquatic Animals › Invertebrates › Molluscs › Snails

Interesting Facts about Marine Snails

[Shelled Gastropods] [Phylum: Mollusca] [Class: Gastropoda] [Order: Stylommatophora] [Family: Subulinidae]

You can find this group of slow-moving marine gastropod mollusks living in every ocean. Even so, there are some key differences between the different species of these shelled organisms.

This section contains a collection of fun and interesting facts about sea snails and how their role in saltwater seas and oceans differs to that of their land-based counterparts.

Sea Snail Species Appearance and Behavior

Some people think the sea snail is a single species, while others often confuse them with sea slugs (nudibranchs).

In fact, even though the two classifications share some similarities, sea snails are gastropods with an operculum - a hard external shell.

The shell, usually spiral or cone shaped, helps to protect them against their natural predators (e.g. sea stars invertebrates).

For one reason or another, sea snail shells have significant variations in colour, size, and complexity. In most cases, the marine environment is going to determine how fast they grow.

Despite being one of the slowest of all living animals in the ocean, most sea snails discharge a white slimy mucus (mucopolysaccharide) as they travel. As a result, many use tentacles to feel different objects as they move around the seabed and the environment that surrounds them.

Note: Another section contains fun facts about sea butterflies and how they use 'wing-like' arms for swimming and movement.

Sea Snail Anatomy

It is true to say that snails are a diverse group of animals. But, almost all the marine species use one or more gills (respiratory organs) for respiration (breathing).

In spite of that, the intertidal species have a lung instead of a gill. So, they wait for low tide before they get active and they move around in air - not submerged in water.

Some examples of air-breathing snail species are false limpets (Siphonariidae) and those belonging with the family Trimusculidae.

Antennae (Snail Tentacles)

A key feature of bivalve marine mollusks is their short, triangular tentacular organs. Sea snails use their tentacles and eye spots for sensory roles (chemoreception) and for protection.

Some species only have one retractable appendage. Whereas, others have two or four located close to the snail's head.

The purpose?

Through a process known as olfactory orientation, scent cells on the surface of each tentacle create a picture of its surroundings. In turn, it helps snails search for sediment and pick up food as they glide along the ocean floor.

As a matter of fact, the abalone and top snail species (family Trochidae) have many small tentacles at the edge of the pallial curtain (the mantle).

Mollusk Shells

By and large, the outer shell of most sea snail species is spiral shaped and curled (like a coil). However, the case of some aquatic snails (especially limpets) is more patelliform (conical).

The shell of tiny bivalve gastropod mollusks in the family Juliidae consists of two individual and hinged valves, like plates.

Most marine snail shells are small. But, one of the biggest living shelled gastropods is the Australian trumpet snail (Syrinx aruanus), with an exoskeleton measuring up to ninety one (91) centimetres (36 inches).

Interesting Fact: The concentration of oxygen isotopes, the water temperature, and food availability, all affect the growth rate of gastropod shells.

Physical Structure of Aquatic Snails

The outer shell of a sea snail provides it with some protection from external threats, by hiding its soft body inside it. As a result, it is difficult for the majority of ocean predators to eat aquatic snail species.

Another interesting fact about sea snails is that they do not have normal teeth. Instead, they have a radula located inside their mouth which they use to scrape, grind, and tear apart their favourite food.

A muscular organ (ventral foot) located underneath its body helps it move around the ocean floor.

Sea Snails Diet and Predators

Most species of marine snails feed on sea plants, algae, and seaweed. So, they are herbivores. Even so, some sea snails are omnivorous scavengers that eat other small animals, especially annelid worms and tiny fish for extra nutrients.

The algae and plants that grow on rocks and other solid surfaces form the main diet and sustenance for saltwater snails.

Here's the thing:

It's not uncommon for certain kinds of sea snail to also be a predator. For example, the deadly cone-shaped snail (conidae) is famous for its venomous sting. This species uses a "harpoon-like" stinger to neutralise and kill their prey with conotoxins.

Marine Snail Habitat and Distribution

Despite limited information being available, it seems that most oceans around the world will contain some species of water-based snails.

The inaccuracies around sea snail habitat and range occur because the specimens that live at the tide level (or low tide) often get classed as land snails.

Nonetheless, you can find examples of caenogastropoda around the rocky reefs and seagrass beds of the Atlantic, the Arctic, and the equatorial warm tropics of the Indian Ocean.

Most species will attach themselves to some kind of rock structure underwater. But, they will also hunt for food by burying themselves into the softer sediment of the sea floor.

Sea Snail Reproductive Process

Like many gastropod mollusks, saltwater sea snails reproduce via an external process and display a 'courtship' as part of the mating ritual.

As a result, the female produces eggs and engages in asexual reproduction. She will try to release the eggs around rocky outcrops or into the water column where fertilisation can take place.

Here's an interesting fact:

Terrestrial snails are mostly hermaphroditic. Whereas, sea snails are gonochoristic - meaning each sex contains a set of organs that it uses to reproduce.

In most cases, it takes up to four (4) weeks for sea snail eggs to hatch after they've been fertilised. Then, juvenile sea snails usually stay in the nest for another twelve (12) weeks to avoid being eaten.

Threats: Are Sea Snails Endangered?

Climate change, underwater pollution, and overfishing are having a detrimental effect on many sea creatures and delicate marine ecosystems.

In general, sea snails thrive best around rock and reef formations. Thus, any destruction of these reef ecosystems will reduce what was once a thriving population of ocean snails.

Important: Some of the world's biggest sea snails (e.g. the horse conch) are at risk of extinction. Furthermore, the World Conservation Organization (IUCN) updated the scaly-foot snail (found in the Indian Ocean) to the Red List of Endangered Species in July 2019.

A to Z List of Sea Snail Species

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