Gastropods - What they are, characteristics and examples with PHOTOS

2024 Author: Carl Johnson | [email protected]. Last modified: 2024-01-08 06:01

Within animal biodiversity we find that each group is peculiar, since their evolutionary aspects have allowed them to be distinguished for various reasons. Thus, we find the gastropods, animals mainly of aquatic habits but that have also conquered the terrestrial environment to a lesser extent. The taxonomy of these animals is very varied, to the point that thousands of fossil and living species have been identified. In this article on our site, we present information about what gastropods are, their characteristics and examples

What are gastropods?

Gastropods are a class of invertebrate animals, belonging to the phylum of molluscs, and usually, depending on the type, are called such as snails, land slugs, sea slugs, limpets, sea hares, sea butterflies, among others.

They are a highly diverse group, in fact the largest within their phylum, with an interesting and successful evolutionary history, evidenced by the adaptive radiationthat they have had, that is, that they diversified into a variety of different forms and customs.

Discover in the next article on our site the Types of molluscs, their characteristics and examples, here.

Gastropods - What they are, characteristics and examples. - What are gastropods?

Characteristics of gastropods

Due to its diversity and radiation, there are few general characteristics that can be mentioned about this group of animals. However, let's get to know its main features.

The group is made up of more than 65,000 species: between those that are alive and those that are fossils.
They have conquered different media: marine, terrestrial and fresh water. Although the greatest diversity is found in the seas.
They have a varied size: in the marine species we find the most minute, barely almost a millimeter in diameter, while There are land snails that measure about 20 centimeters long. However, there are marine species that can measure up to 130 cm in length.
They have developed different forms: there are primitive marine forms and other terrestrial forms that breathe air, so they are more evolved.
In essence its symmetry is bilateral: however, as they perform a turning or twisting process, they end up with an asymmetrical shape.
They may or may not have a shell: which is always in one piece, which is why they were previously known as univalves.
The shell varies: it can be very visible in some species, or not appreciated because it is tiny and internal.
On the other hand, the shell has different shapes: when it is present it can be coiled as seen in many species, or it does not necessarily come to present this form. Also, the direction in which the shell is rolled is genetically determined and can be either to the right or to the left. You may be interested in taking a look at the following article about the different types of seashells that exist.
They are present in various aquatic environments and at different depths: thus, they are in the marine, brackish, fresh waters, swamps, ponds, among others.
On land may have more restrictions depending on: humidity, acidity, presence of minerals and temperatures, however, they have diversified in forests, underground and rocks, trees, grasses and even live on other animals.
They are usually very sedentary and slow-moving.
Your locomotion is varied: it can be through the swim, climb or slide. Certain species can be easily buried.
There is diversity of types of food: many species are herbivores, but there are also carnivores and scavengers.
You can practice different types of breathing: it is common for various species to breathe through gills, others through the mantle, and there are also those they do this through a lung-like structure.
The circulatory system is open: besides almost they all have a kind of single kidney.
The nervous system is well-developed: which consists of three pairs of ganglia that connect to nerves.
They have eyes or simple photoreceptors: in addition to other tactile organs or chemoreceptors.
They can have separate sexes or not: that is, they can be monoecious and there are also dioecious.
The type of fertilization can vary: in many species fertilization is internal, but there are more primitive gastropods with external fertilization.
Practice different reproductive strategies: there are many species of oviparous gastropods and some ovoviviparous.
Certain species of snails are poisonous.

Gastropods - What they are, characteristics and examples. - Characteristics of gastropods

Types of gastropods

Given the diversity of gastropods and their evolutionary history, taxonomy has been a subject of extensive debate over time, which will continue as long as advances and respective studies continue to be made.

In this sense, there is a general classification of the group, eventually considered informal, but which continues to be commonly used, and basically establishes three types (subclasses) of gastropods, which are the following.

Subclass Prosobranch

It is made up of more than 65,000 species and has the following characteristics:

They are mainly marine snails: but we also find certain freshwater gastropods and terrestrial.
The mantle cavity is located in the anterior zone.
The gills or the gill: they are located in front of the heart.
Water circulation in the animal occurs from the left to the right side.
They have a pair of tentacles.
Usually the sexes are separated.
Normally they present operculum: which is the structure that closes the shell.

Subclass Opisthobranch

Some 4,000 species have been identified and among their characteristics we find:

Common names include: sea slugs, sea hares, sea butterflies, and canoe shells.
Most of the group are of marine habits: living under rocks and clumps of algae.
They are usually grouped into two types: those with gills and shells, and those without them, but with secondary gill structures.
They may have a partial or complete detorsion.
Both the anus and the gill, when present, are located towards the right or posterior side of the animal.
The sexes are in all cases separated.
The shell is reduced or absent.
Some have chemical defenses.
Certain species have tentacles.
In some cases the foot has been modified into a fin for swimming.

Subclass Pulmonata

There are about 28,000 species and among their main features we can mention:

This group includes: land snails, land slugs and some species that live in brackish water.
In certain cases a detorsion occurs.
The gillshave disappeared: although certain species have a secondary.
The mantle is vascularized and has become a lung for respiration.
Both aquatic and terrestrial species have a pair of tentacles.
The species of the group have eyes.

Don't miss the next article on our site with the Types of snails: marine and terrestrial, below.