In our ecosystem there are several types of animals, and this time we will talk a little about mollusks. These animals are part of the group of invertebrates (which have no internal bone structure in the body). There is an extensive variety of species, reaching about 50,000 live and 35,000 already found fossilized. But these fossils were only possible to be found due to the mineral shell that these animals carry, and can then last for many years buried.
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What is Malacology?
The area of biology that is responsible for studying this type of animal is known as Malacology. The studies are focused on physiology (which studies the animal’s mechanical functions), taxonomy (definition of the group to which the animal belongs) and ecology (the environment in which the animal lives). Mollusks can be found in the sea, in places with fresh water and on land.
To be identified as a mollusk, the animal must have a fundamental structure typical of the animals belonging to this group. It has been said before that the diversity of species is very great, but all of them are based on a muscular foot, a limestone shell and an organ responsible for feeding.
Within this group studied by Malacology are, among the most well-known species, the snail (they serve as a guest of human parasites), squid, octopus and escargot, used a lot in cooking and having a rich nutritional value.
The generic mollusk
The generic mollusk lives in water and its food and movements take place on a solid substrate. Its body has an egg shape and is bilaterally symmetrical, with a flat, muscular ventral surface, forming something like a foot. On top of the back it has an oval and convex shell that serves as a shield, protecting the organs responsible for the digestive process, releasing a secretion from the underlying epidermis (known as mantle) being quite active at its edges.
Knowing a little more about the generic mollusk
The shell, as already mentioned, is on the body of the mollusk, except for a small piece of the body where the mantle cavity is located. It is in this region that pairs of gills and openings of pairs of nephrids are found.
The gills contain blood vessels, muscles and nerves. They are called bipectinates because they have filaments on a single side of the axis. They are responsible for a process that causes water to propel through the mantle cavity. This stream of water brings a sediment that is retained in the mucus of the gills and is then transported upwards and then swept out.
It feeds on very fine algae and other organisms that grow on rocks. In the mouth it has a type of cartilaginous, muscular and elongated mass, extending medially to the radula, composed of transverse rows of teeth. The radula serves to scrape surfaces since the food system only absorbs small fine particles. The collected food is sorted and then sent to the digestive system.
Classifications of molluscs
According to studies on the taxonomy of these animals, mollusks are classified into up to seven classes, namely:
- Monoplacophora
- Polyplacophora
- Aplacophora
- Gastropoda
- Bivalvia
- Scaphopoda
- Cephalopoda
