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ORGAN SYSTEM

Bilateral Symmetry

DIGESTIVE SYSTEM

CIRCULATORY SYSTEM / EXCRETION

The nervous system of gastropods includes the peripheral nervous system and the central nervous system. The central nervous system consist of ganglia connected by nerve cells. It includes paired ganglia: the cerebral ganglia, pedal ganglia, osphradial ganglia, pleural ganglia, parietal ganglia and the visceral ganglia. There are sometimes also buccal ganglia.

Courtship is a part of mating behavior in some gastropods including some of the Helicidae. Again, in some land snails, an unusual feature of the reproductive system of gastropods is the presence and utilization of love darts. In many marine gastropods other than the opisthobranchs, there are separate sexes; most land gastropods however are hermaphrodites.

NERVOUS SYSTEM

THERMOREGULATION

  • Gastropods have open circulatory system and the transport fluid is hemolymph. Hemocyanin is present in the hemolymph as the respiratory pigment.
  • The primary organs of excretion in gastropods are nephridia, which produce either ammonia or uric acid as a waste product. The nephridium also plays an important role in maintaining water balance in freshwater and terrestrial species. Additional organs of excretion, at least in some species, include pericardial glands in the body cavity, and digestive glands opening into the stomach.

This species is commonly prefers to attach to sloped or vertical rock surfaces, or hang from the underside of rocks. This may be a method of thermoregulation, because , it would absorb the maximum solar radiation, whereas on sloped or vertical surfaces it absorbs less energy (and thus heat).

REPRODUCTION

GROWTH

GASTROPODA

  • Gastropoda (previously known as univalves and sometimes spelled "Gasteropoda") are a major part of the phylum Mollusca, and are the most highly diversified class in the phylum, with 60,000 to 80,000 living snail and slug species

Phylum Mollusca

  • The Mollusca is one of the most diverse groups of animals on the planet, with at least 50,000 living species (and more likely around 200,000).
  • It includes such familiar organisms as snails, octopuses, squid, clams, scallops, oysters, and chitons.

Environment

and

lifestyle

How and what

they eat

  • The class Gastropoda has an extraordinary diversification of habitats. Representatives live in gardens, woodland, deserts, and on mountains; in small ditches, great rivers and lakes; in estuaries, mudflats, the rocky intertidal, the sandy subtidal, in the abyssal depths of the oceans including the hydrothermal vents, and numerous other ecological niches, including parasitic ones.
  • Marine gastropods include some that are herbivores, detritus feeders, predatory carnivores, scavengers, parasites, and also a few ciliary feeders, in which the radula is reduced or absent.
  • Land-dwelling species can chew up leaves, bark, fruit and decomposing animals while marine species can scrape algae off the rocks on the sea floor.

CLASS GASTROPODA

  • Most shelled gastropods have a one piece shell, typically coiled or spiraled. Which usually opens on the right-hand side.
  • Numerous species have an operculum, which in many species acts as a trapdoor to close the shell. This is usually made of a horn-like material. In the land slugs, the shell is reduced or absent, and the body is streamlined.
  • Some sea slugs are very brightly colored. This serves either as a warning, or to camouflage them from the brightly colored hydroids, sponges and seaweeds.

Snails grow rings inside of the shell as they grow. This is how scientists and researchers are able to get a good idea of how old they are. For the most part it seems that snails live a life that is slow paced and very basic. You can tell if a snail is full grown or not by looking at the part of the shell that opens up to the rest of the body. If there is a small lip on it then the snail won’t grow anymore. If it is missing then the snail still will continue to get bigger.

BODY WEIGHT

THE END

The digestive system of gastropods (slugs and snails of every kind) has evolved to suit almost every kind of diet and feeding behavior. Gastropods as the largest taxonomic class of the mollusca are very diverse indeed: the group includes carnivores, herbivores, scavengers, filter feeders, and even parasites.

During their development, gastropods undergo a process known as torsion, a twisting of their body along its head-to-tail axis. This twisting means that the head is between 90 and 180 degrees offset relative to their foot. Torsion is the result of asymmetrical growth, with more growth occurring on the left side of the body. Torsion causes the loss of the right side of any paired appendages. Thus, although gastropods are still considered to be bilaterally symmetrical (that's how they start out), by the time they become adults, gastropods that have undergone torsion have lost some elements of their "symmetry". The adult gastropod ends up configured in such a way that its body and internal organs are twisted and the mantle and mantle cavity are above its head. It should be noted that torsion involves the twisting of the gastropod's body, it has nothing to do with the coiling of the shell.

  • Because molluscs have a soft body they are more fragile. They also have more difficulty to support their bodies in terrestrial environments or to fixate to substrates in aquatic habitats. Many species solve these problems by secreting a calcareous carapace, or shell, an exoskeleton to support and protect them and to prevent dehydration.
  • The so-called foot is the largest part of a gastropod's body visible outside of the shell. Most gastropods' foot is developed to a flat crawling sole at its lower (ventral) side. This points to the most frequent way of snail locomotion: Crawling.

PHYLUM MOLLUSCA

BY JAMES VILLAMIZAR

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