The gastropods portal
The gastropods (), more commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca, called Gastropoda. This class comprises snails and slugs from saltwater, from freshwater, and from the land. There are many thousands of species of sea snails and slugs, as well as freshwater snails, freshwater limpets, and land snails and slugs.
The class Gastropoda contains a vast total of named species, second only to the insects in overall number. The fossil history of this class goes back to the Late Cambrian. , 721 families of gastropods are known, of which 245 are extinct and appear only in the fossil record, while 476 are currently extant with or without a fossil record.
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 65,000 to 80,000 living snail and slug species. The anatomy, behavior, feeding, and reproductive adaptations of gastropods vary significantly from one clade or group to another. Therefore, it is difficult to state many generalities for all gastropods.
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.
Although the name "snail" can be, and often is, applied to all the members of this class, commonly this word means only those species with an external shell big enough that the soft parts can withdraw completely into it. Those gastropods without a shell, and those with only a very reduced or internal shell, are usually known as slugs; those with a shell into which they can partly but not completely withdraw are termed semi-slugs.
The marine shelled species of gastropod include species such as abalone, conches, periwinkles, whelks, and numerous other sea snails that produce seashells that are coiled in the adult stage—though in some, the coiling may not be very visible, for example in cowries. In a number of families of species, such as all the various limpets, the shell is coiled only in the larval stage, and is a simple conical structure after that.
A love dart
is a hard, sharp, calcareous
dart which some hermaphroditic land snails
create. Love darts are made in sexually mature animals only, and are used as part of the sequence of events during courtship
before actual mating
Prior to copulation, each of the two snails (or slugs) attempt to "shoot" one or more darts into the other snail (or slug). There is no organ to receive the dart; this action is more analogous to a stabbing, or to being shot with an arrow. The dart does not fly through the air to reach its target however; instead it is fired as a contact shot.
The love dart is emphatically not a penial stylet (in other words this is not an accessory organ for sperm transfer). The exchange of sperm between each of the two land snails is a completely separate part of the mating progression. Nevertheless, recent research shows that use of the dart can strongly favor the reproductive outcome for the snail that is able to lodge a dart first in its partner. This is because mucus on the dart introduces a hormone-like substance that allows far more of its sperm to survive.
William John Swainson FLS
(8 October 1789 – 6 December 1855), was an English ornithologist
and artist. He was born in Dover Place, St. Mary Newington, London
, the eldest son of John Timothy Swainson, an original fellow of the Linnean Society
. He was cousin of the amateur botanist Isaac Swainson
In 1816 Swainson accompanied the explorer Henry Koster to Brazil. They did not spend a long time on shore because of a revolution, but Swainson returned to England in 1818 in his words "a bee loaded with honey", with a collection of over 20,000 insects, 1,200 species of plants, drawings of 120 species of fish, and about 760 bird skins. (Read more...)
Did you know?
- ... that the marine gastropod Coriocella nigra (pictured) has five lobes on its body?
- ... that the scale worm Arctonoe vittata protects the keyhole limpet Diodora aspera (shell pictured) with which it lives, by attacking predatory starfish?
- ... that the Cretaceous snail Condonella was described in 1927, but not placed into a snail family until 2000?
- ... that Acmella nana (shell pictured) is the smallest known land snail?
- ... that the fragile shell of the glassy nautilus Carinaria cristata (pictured) was at one time considered to be worth more than its weight in gold?
- ... that Spurilla neapolitana (pictured) defends itself with stinging cells derived from the sea anemones it eats?
- ... that Pupilla pratensis (shell pictured) has long been neglected in the malacological literature?
- ... that there are 12 endemic species of freshwater snails in Lake Skadar (map pictured)?
- ... that the land snail Balea sarsii (shell pictured) has been overlooked for a long time?
- ... that the land snail Vertigo ultimathule (shell pictured) is endemic to the northernmost part of Scandinavia?
- ... that flashes of light emitted by the sea snail Hinea brasiliana (shell pictured) may act as a "burglar alarm"?
- ... that Candidula arganica, a snail found in the north of the Iberian Peninsula, lives primarily in meadows?
- ... that Candidula spadae, a snail native to Central Italy, is at risk in part because of tourist activities?
- ... that the subterranean freshwater snail Hauffenia sp. from Slovakia (shell pictured) has been an undescribed species since the 1980s?
- ... that land snails of the genus Abbottella (Abbottella calliotropis shell pictured) live on the islands of Hispaniola and Cuba?
- ... that the snail Tonna galea (pictured) is one of very few species of prosobranch gastropods that are luminescent?
- ... that the land snail Notodiscus hookeri (shell pictured) has unique shell structure among all gastropods?
- ... that the microscopic cave snail Zospeum tholussum (pictured) is so slow that in a week's time it may only move a few millimeters or centimeters in circles?
- ... that the land snail Omalonyx convexus (pictured) can also be found submerged among macrophytes?
- ... that the malacologist S. Peter Dance said the shell of Pterynotus loebbeckei, (pictured), was the "most exquisite natural object" he had ever seen?
- ... that the only brackish-water pachychilid species, Faunus ater (shell pictured), has a shell that is unique among all the Cerithioidea?
- ... that the owl limpet (pictured) maintains a small meadow of algal turf for its own exclusive use?
In the news
- 16 July 2010: A new subfamily is established within the Chondrinidae.
- A list of new Wikipedia articles about gastropods, including those that simply mention the words snail, slug, conch, etc. A bot creates this list, usually every three days.
The nudibranch Tambja gabrielae
, from the family Polyceridae
, has bright yellow spots and stripes on a dark green background. At the head end, towards the left, the two rhinophores
are clearly visible, and halfway down the back of the animal its gill
rosette can be seen. In this image, all of these structures are being bent back by a strong water current.
Lists of gastropods
- Gastropoda, snail, slug, land snail, freshwater snail, sea snail, sea slug
- Gastropod shell, operculum, radula, love dart, clausilium
- Digestive system of gastropods, respiratory system of gastropods, circulatory system of gastropods, excretory system of gastropods, sensory organs of gastropods, nervous system of gastropods, reproductive system of gastropods
- Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005), and also, changes in the taxonomy of gastropods since 2005
- Gastropods with significant positive human impact
- Gastropods with significant negative human impact
Categories about gastropods:
Request to editors: please do not create any more categories of gastropods by country. Instead create list articles, article with a list of the marine or non-marine gastropods of whichever country or area you are interested in. We would also like to empty and delete the two remaining country categories we have, adding that information to list articles instead. Thank you.