A gill is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are kept moist. The microscopic structure of a gill presents a large surface area to the external environment. Branchia is the zoologists' name for gills.
The gastropods, commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda.
Aquatic respiration is the process whereby an aquatic organism exchanges respiratory gases with water, obtaining oxygen from oxygen dissolved in water and excreting carbon dioxide and some other metabolic waste products into the water.
Heterobranchia, the heterobranchs, is a taxonomic clade of snails and slugs, which includes marine, aquatic and terrestrial gastropod mollusks.
A siphon is an anatomical structure which is part of the body of aquatic molluscs in three classes: Gastropoda, Bivalvia and Cephalopoda.
The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.
Limpets are a group of aquatic snails that exhibit a conical shell shape (patelliform) and a strong, muscular foot. Limpets are members of the class Gastropoda, but are polyphyletic, meaning the various groups called "limpets" descended independently from different ancestral gastropods. This general category of conical shell is known as "patelliform" (dish-shaped). All members of the large and ancient marine clade Patellogastropoda are limpets. Within that clade, the members of the Patellidae family in particular are often referred to as "true limpets".
The pneumostome or breathing pore is a respiratory opening of the external body anatomy of an air-breathing land slug or land snail. It is a part of the respiratory system of gastropods.
The periostracum is a thin, organic coating that is the outermost layer of the shell of many shelled animals, including molluscs and brachiopods. Among molluscs, it is primarily seen in snails and clams, i.e. in gastropods and bivalves, but it is also found in cephalopods such as Allonautilus scrobiculatus. The periostracum is an integral part of the shell, and it forms as the shell forms, along with the other shell layers. The periostracum is used to protect the organism from corrosion.
Torsion is a gastropod synapomorphy which occurs in all gastropods during larval development. Torsion is the rotation of the visceral mass, mantle, and shell 180˚ with respect to the head and foot of the gastropod. This rotation brings the mantle cavity and the anus to an anterior position above the head.
Bithyniidae is a family of small freshwater snails with an operculum, aquatic gastropod molluscs in the clade Littorinimorpha.
The siphonal canal is an anatomical feature of the shells of certain groups of sea snails within the clade Neogastropoda. Some sea marine gastropods have a soft tubular anterior extension of the mantle called a siphon through which water is drawn into the mantle cavity and over the gill and which serves as a chemoreceptor to locate food. In certain groups of carnivorous snails, where the siphon is particularly long, the structure of the shell has been modified in order to house and protect the soft structure of the siphon. Thus the siphonal canal is a semi-tubular extension of the aperture of the shell through which the siphon is extended when the animal is active.
Cyclophoroidea is a superfamily of land snails with an operculum, terrestrial gastropods within the informal group Architaenioglossa, that belongs to the clade Caenogastropoda.
Chrysomallon squamiferum, commonly known as the scaly-foot gastropod, scaly-foot snail, sea pangolin, or volcano snail is a species of deep-sea hydrothermal-vent snail, a marine gastropod mollusc in the family Peltospiridae. This vent-endemic gastropod is known only from deep-sea hydrothermal vents in the Indian Ocean, where it has been found at depths of about 2,400–2,900 m (1.5–1.8 mi). C. squamiferum differs greatly from other deep-sea gastropods, even the closely related neomphalines. In 2019, it was declared endangered on the IUCN Red List, the first species to be listed as such due to risks from deep-sea mining of its vent habitat.
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks. Around 85,000 extant species of molluscs are recognized. The number of fossil species is estimated between 60,000 and 100,000 additional species. The proportion of undescribed species is very high. Many taxa remain poorly studied.
The digestive system of gastropods has evolved to suit almost every kind of diet and feeding behavior. Gastropods as the largest taxonomic class of the mollusca are very diverse: the group includes carnivores, herbivores, scavengers, filter feeders, and even parasites.
The respiratory system of gastropods varies greatly in form. These variations were once used as a basis for dividing the group into subclasses. The majority of marine gastropods breathe through a single gill, supplied with oxygen by a current of water through the mantle cavity. This current is U-shaped, so that it also flushes waste products away from the anus, which is located above the animal's head, and would otherwise cause a problem with fouling.
This outline is provided as an overview of, and organized list of articles relevant to, the subject of gastropods :
Bythinellidae is a family of small freshwater snails with an operculum, aquatic gastropod molluscs in the order Littorinimorpha.
Pair of large, grey gills visible inside the mantle cavity of a giant squid
