Giuseppe Antonio Risso, called Antoine Risso, was a Niçard naturalist. Risso was born in the city of Nice in the Duchy of Savoy, studied under Giovanni Battista Balbis, he published Ichthyologie de Nice, Histoire naturelle de l'Europe méridionale and Histoire Naturelle des Orangers. Risso's dolphin was named after him, he is denoted by the author abbreviation Risso. Rissoa Freminville in Desmarest, 1814: a genus of gastropods Rissoella Gray, 1847: a genus of gastropod Electrona risso: a lanternfish He named 549 marine genera and species. IPNI gives 81 records for Risso. Risso A.. "Memoire sur quelques Gasteropodes nouveaux, Nudibranches et Tectibranches observes dans la Mer de Nice". Journal de Physique, de Chimie, d'Histoire Naturelle et des Arts 87: 368-377. Risso A.. Histoire naturelle des principales productions de l'Europe Méridionale et particulièrement de celles des environs de Nice et des Alpes Maritimes. Paris, Levrault.. Vol. 1: XII + 448 pp. 1 plate.. Vol. 2: VII + 482 pp. 8 pl... Vol. 3: XVI + 480 pp. 14 pl...
Vol. 4: IV + 439 pp. 12 pl... Vol. 5: VIII + 400 pp. 10 pl.. Emig C. C. 2012. Révision des espèces de brachiopodes décrites par A. Risso. Carnets de Géologie / Notebooks on Geology, Article 2012/02 with the scientific bibliography of A. Risso in an appendix Jules René Bourguignat. Étude synonymique sur les mollusques des Alpes maritimes publiés par A. Risso en 1826. Paris: J. B. Baillière. Works by or about Antoine Risso at Internet Archive Site Risso: http://paleopolis.rediris.es/benthos/Risso/
Mollusca is the second largest phylum of invertebrate animals. The members are known as mollusks. Around 85,000 extant species of molluscs are recognized; the number of fossil species is estimated between 100,000 additional species. Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs live in freshwater and terrestrial habitats, they are diverse, not just in size and in anatomical structure, but in behaviour and in habitat. The phylum is divided into 8 or 9 taxonomic classes, of which two are extinct. Cephalopod molluscs, such as squid and octopus, are among the most neurologically advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known invertebrate species; the gastropods are by far the most numerous molluscs and account for 80% of the total classified species. The three most universal features defining modern molluscs are a mantle with a significant cavity used for breathing and excretion, the presence of a radula, the structure of the nervous system.
Other than these common elements, molluscs express great morphological diversity, so many textbooks base their descriptions on a "hypothetical ancestral mollusc". This has a single, "limpet-like" shell on top, made of proteins and chitin reinforced with calcium carbonate, is secreted by a mantle covering the whole upper surface; the underside of the animal consists of a single muscular "foot". Although molluscs are coelomates, the coelom tends to be small; the main body cavity is a hemocoel. The "generalized" mollusc's feeding system consists of a rasping "tongue", the radula, a complex digestive system in which exuded mucus and microscopic, muscle-powered "hairs" called cilia play various important roles; the generalized mollusc has three in bivalves. The brain, in species that have one, encircles the esophagus. Most molluscs have eyes, all have sensors to detect chemicals and touch; the simplest type of molluscan reproductive system relies on external fertilization, but more complex variations occur.
All produce eggs, from which may emerge trochophore larvae, more complex veliger larvae, or miniature adults. The coelomic cavity is reduced, they have kidney-like organs for excretion. Good evidence exists for the appearance of gastropods and bivalves in the Cambrian period, 541 to 485.4 million years ago. However, the evolutionary history both of molluscs' emergence from the ancestral Lophotrochozoa and of their diversification into the well-known living and fossil forms are still subjects of vigorous debate among scientists. Molluscs still are an important food source for anatomically modern humans. There is a risk of food poisoning from toxins which can accumulate in certain molluscs under specific conditions and because of this, many countries have regulations to reduce this risk. Molluscs have, for centuries been the source of important luxury goods, notably pearls, mother of pearl, Tyrian purple dye, sea silk, their shells have been used as money in some preindustrial societies. Mollusc species can represent hazards or pests for human activities.
The bite of the blue-ringed octopus is fatal, that of Octopus apollyon causes inflammation that can last for over a month. Stings from a few species of large tropical cone shells can kill, but their sophisticated, though produced, venoms have become important tools in neurological research. Schistosomiasis is transmitted to humans via water snail hosts, affects about 200 million people. Snails and slugs can be serious agricultural pests, accidental or deliberate introduction of some snail species into new environments has damaged some ecosystems; the words mollusc and mollusk are both derived from the French mollusque, which originated from the Latin molluscus, from mollis, soft. Molluscus was itself an adaptation of Aristotle's τὰ μαλάκια ta malákia, which he applied inter alia to cuttlefish; the scientific study of molluscs is accordingly called malacology. The name Molluscoida was used to denote a division of the animal kingdom containing the brachiopods and tunicates, the members of the three groups having been supposed to somewhat resemble the molluscs.
As it is now known these groups have no relation to molluscs, little to one another, the name Molluscoida has been abandoned. The most universal features of the body structure of molluscs are a mantle with a significant cavity used for breathing and excretion, the organization of the nervous system. Many have a calcareous shell. Molluscs have developed such a varied range of body structures, it is difficult to find synapomorphies to apply to all modern groups; the most general characteristic of molluscs is they are bilaterally symmetrical. The following are present in all modern molluscs: The dorsal part of the body wall is a mantle which secretes calcareous spicules, plates or shells, it overlaps the body with enough spare room to form a mantle cavity. The anus and genitals open into the mantle cavity. There are two pairs of main nerve cords. Other characteristics that appear in textbooks have significant exceptions: Estimates of accepted described living species of molluscs vary from 50,000 to a maximum of 120,000 species.
In 1969 David Nicol estimated the probable total number of living mollusc species at 107,000 of which were ab
Panpulmonata is a taxonomic clade of snails and slugs in the clade Heterobranchia within the clade Euthyneura. Panpulmonata was established as a new taxon by Jörger et al. in October 2010. The older name "Pulmonata" referred to a group of gastropods which were considered to be "air-breathers"; this meaning does not apply to the panpulmonate groups Acochlidia and Pyramidelloidea, was inaccurate when applied to some of the more traditional pulmonate taxa such as Siphonarioidea or Hygrophila, most members of which lack permanently air-filled lungs. However, the term Panpulmonata was chosen by Jörger et al. to provide some continuity in the terminology. Panpulmonata consists of following taxa: Siphonarioidea Sacoglossa Glacidorboidea Amphiboloidea Pyramidelloidea Hygrophila Acochlidiacea Eupulmonata: Stylommatophora, Systellommatophora, Otinoidea, Trimusculoidea; this cladogram shows phylogenic relations within the Heterobranchia, as proposed by Jörger et al.: Changes in the taxonomy of gastropods since 2005#Heterobranchia Heterobranchia#2010 taxonomy Acochlidiacea#2010 taxonomy This article incorporates CC-BY-2.0 text from the reference
Hygromia cinctella, known as the girdled snail, is a small European species of air-breathing land snail, native to the Mediterranean region, that belongs to the terrestrial pulmonate gastropod mollusk family Hygromiidae. For terms see gastropod shell Hygromia cinctella possesses a 6–7 × 10–12 mm dextral shell composed of 5–6 whorls with shallow sutures that form a high conical top and a flattened underside; the last whorl is keeled. The keel has a characteristic white edge, which'girdles' the shell, giving the snail its common name; the aperture is simple without a lip inside. The umbilicus is narrow and covered by the reflected columellar margin; the shell colour is variable, from whitish grey to horny brown with dark spots translucent and rather striated. The animal is light greyish or with a yellowish hue with darker greyish or brownish head and tentacles. Variation: In Sicily, colour morphs include green and yellow and reddish with colour bands; this snail is native to various European countries around the Mediterranean, including south-east France, southern Switzerland, north-west Croatia and Slovenia.
It has been introduced and is becoming established in Great Britain, Czech Republic, Belgium, the Netherlands and the United States. It has been recorded in Ireland. Hygromia cinctella was described as new to Britain by writer Alex Comfort based on specimens he had found in the Paignton area of Devon in April 1950. Subsequently, it was realised that specimens of this species had been found in the area from 1945 onwards, but these had been misidentified as the related species and close congener Hygromia limbata, itself a non-native species only discovered in Britain in 1919, it remained predominantly confined to the south-east of England until the mid 1970s, at which point it began to extend its range dramatically. It now has a scattered distribution which extends as far north as Scotland, the first Scottish record being in Glasgow in 2008. In Britain it seems to favour anthropogenic habitats such as gardens and waste ground. Hygromia cinctella has so far been discovered at two sites in Ireland.
The latter population is thought to have been accidentally introduced along with garden plants brought from a site near Bristol. Where they occur, numerous Hygromia cinctella can be found together in large aggregations, they can be active at night on paths and flagstones. They can rest high in the leaf litter and underside of logs; the species can be active in cold weather and survives cold winters in Central Europe, therefore its recent expansion might have more to do with increased transportation than with climate change. This species uses love darts in its mating behavior. 3. Van den Neucker T. & Scheers K.. The recent colonisation and rapid spread in Belgium of the alien girdled snail Hygromia cinctella. Journal of Conchology 41:779-780. PDF Hygromia cinctella at Animalbase taxonomy,short description, biology,status, images Hygromia cinctella images at Encyclopedia of Life Fauna Europaea Search Distribution Pall-Gergely, B. 2011. Hygromia cinctella. In: IUCN 2012. IUCN Red List of Threatened Species.
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A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. Land snail is the common name for terrestrial gastropod mollusks. However, it is not always easy to say which species are terrestrial, because some are more or less amphibious between land and fresh water, others are amphibious between land and salt water; the majority of land snails are pulmonates. That is, they have a lung and breathe air. A minority, belong to much more ancient lineages whose anatomy includes a gill and an operculum. Many of these operculate land snails live in habitats or microhabitats that are sometimes damp or wet, such as in moss. Land snails have a strong muscular foot. Like other mollusks, land snails have a mantle, they have one or two pairs of tentacles on their head, their internal anatomy includes a primitive brain. In terms of reproduction, all known species of land snails are hermaphrodites and most lay clutches of eggs in the soil. Tiny snails hatch out of the egg with a small shell in place, the shell grows spirally as the soft parts increase in size.
Most land snails have shells. A wide range of different vertebrate and invertebrate animals prey on land snails, they are used as food by humans in various cultures worldwide, are raised on farms in some areas for use as food. Land snails move by gliding along on their muscular foot, lubricated with mucus and covered with epithelial cilia; this motion is powered by succeeding waves of muscular contractions that move down the ventral of the foot. This muscular action is visible when a snail is crawling on the glass of a window or aquarium. Snails move at a proverbially low speed. Snails secrete mucus externally to keep their soft bodies from drying out, they secrete mucus from the foot to aid in locomotion by reducing friction, to help reduce the risk of mechanical injury from sharp objects, meaning they can crawl over a sharp edge like a straight razor and not be injured. The mucus that land snails secrete with the foot leaves a slime trail behind them, visible for some hours afterwards as a shiny "path" on the surface over which they have crawled.
Snails have a mantle, a specialized layer of tissue which covers all of the internal organs as they are grouped together in the visceral mass. The mantle extends outward in flaps which reach to the edge of the shell and in some cases can cover the shell, which are retractable; the mantle is attached to the shell, creates the shell and makes shell growth possible by secretion. Most molluscs, including land snails, have a shell, part of their anatomy since the larval stage, which grows with them in size by the process of secreting calcium carbonate along the open edge and on the inner side for extra strength. Although some land snails create shells that are entirely formed from the protein conchiolin, most land snails need a good supply of calcium in their diet and environment to produce a strong shell. A lack of calcium, or low pH in their surroundings, can result in thin, cracked, or perforated shells. A snail can repair damage to its shell over time if its living conditions improve, but severe damage can be fatal.
When retracted into their shells, many snails with gills are able to protect themselves with a door-like anatomical structure called an operculum. Land snails range in size; the largest living species is the Giant African Snail or Ghana Tiger Snail, which can measure up to 30 cm. The largest land snails of non-tropical Eurasia are endemic Caucasian snails Helix buchi and Helix goderdziana from the south-eastern Black Sea area in Georgia and Turkey. In most land snails the eyes are carried on the first set of tentacles which are roughly 75% of the width of the eyes; the second set of tentacles act as olfactory organs. Both sets of tentacles are retractable in land snails. A snail breaks up its food using the radula inside its mouth; the radula is a chitinous ribbon-like structure containing rows of microscopic teeth. With this the snail scrapes at food, transferred to the digestive tract. In a quiet setting, a large land snail can be heard'crunching' its food: the radula is tearing away at the surface of the food that the snail is eating.
The cerebral ganglia of the snail form a primitive brain, divided into four sections. This structure is much simpler than the brains of mammals and birds, but nonetheless, snails are capable of associative learning; as the snail grows, so does its calcium carbonate shell. The shell grows additively, by the addition of new calcium carbonate, secreted by glands located in the snail's mantle; the new material is added to the edge of the shell aperture. Therefore, the centre of the shell's spiral was made when the snail was younger, the outer part when the snail was older; when the snail reaches full adult size, it may build a thickened lip around the shell aperture. At this point the snail stops growing, begins reproducing. A snail's shell forms a logarithmic spiral. Most snail shells are right-handed or dextral in coiling, meaning that if the shell is hel
Heterobranchia, the heterobranchs, is a taxonomic clade of snails and slugs, which includes marine and terrestrial gastropod mollusks. Heterobranchia is one of the main clades of gastropods. Heterobranchia comprises three informal groups: the lower heterobranchs, the opisthobranchs and the pulmonates; the three subdivisions of this large clade are quite diverse: The Lower Heterobranchia includes shelled marine and freshwater species. Opisthobranchia are all marine species, some shelled and some not; the internal organs of the opisthobranchs have undergone detorsion. The Pulmonata includes the majority of land snails and slugs, many freshwater snails, a small number of marine species; the mantle cavity of the Pulmonata is modified into an air-breathing organ. They are characterized by detorsion and a symmetrically-arranged nervous system; the pulmonates always lack an operculum and are hermaphroditic. The families included in Heterobranchia have been placed in many different parts of the taxonomic class of gastropods.
Earlier authors considered Heterobranchia to consist of only marine gastropods, conceptualized it as a borderline category, intermediate between the Opisthobranchia & Pulmonata, all the other gastropods. The category Heterostropha within the Heterobranchia, which includes such families as Architectonicidae, the sundial or staircase snails, is characterized by a shell which has a heterostrophic protoconch, in other words the apical whorls are coiled in the opposite plane to the adult whorls; the classification of this group was revised by Ponder & Warén in 1988. According to the older taxonomy of the Gastropoda the Heterobranchia were ranked as a superorder. Heterobranchia is one of the main clades of gastropods. For a detailed taxonomy, see Taxonomy of the Gastropoda #Clade Heterobranchia. Jörger et al. have redefined major groups within the Heterobranchia: they created the new clades Euopisthobranchia and Panpulmonata. A cladogram showing phylogenic relations of Heterobranchia as proposed by Jörger et al.: Dinapoli A..
Phylogeny and Evolution of the Heterobranchia. Thesis, Frankfurt am Main, 176 pp. PDF. Dinapoli A.. "The long way to diversity – Phylogeny and evolution of the Heterobranchia"". Molecular Phylogenetics and Evolution. 55: 60–76. Doi:10.1016/j.ympev.2009.09.019. PMID 19778622
Hygromia limbata is a species of small air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Hygromiidae. This species is known to occur in: Great Britain France AnimalBase info at