gastropod


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gastropod

gastropod, member of the class Gastropoda, the largest and most successful class of mollusks (phylum Mollusca), containing over 35,000 living species and 15,000 fossil forms. The shell of gastropods is of one piece (called univalve) and usually coiled or spiraled as in snails, periwinkles, conches, whelks, limpets, and abalones; however, in some forms, as in slugs and sea slugs, it is reduced or completely absent. There is usually a definite head, bearing one or two sensory tentacles and a mouth that is often equipped with a rasplike tongue called a radula. The lower surface of the animal is modified into a large, flattened foot, used by bottom-dwelling forms for creeping about. The foot and other soft parts of the body can usually be completely withdrawn into the shell and the opening covered by a permanent plate called the operculum. Ancient gastropods were probably bilaterally symmetrical, but living species undergo a process known as torsion in which most of the body behind the head rotates 180° so that the anal and urinary openings are relocated behind the head, and the digestive tract and nervous system become U-shaped. Most gastropod species are marine but many groups, notably the pulmonate (lung-bearing) snails, have successfully invaded freshwater and moist terrestrial habitats.

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gastropod

, gasteropod
any mollusc of the class Gastropoda, typically having a flattened muscular foot for locomotion and a head that bears stalked eyes. The class includes the snails, whelks, limpets, and slugs
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Hypomphalocirrus Linsley, 1973 from the Devonian of North America was considered to be a paragastropod, not a gastropod, by Linsley & Kier (1984) but was placed within Euomphaloidea by Bouchet et al.
Egg capsules of the gastropod Concholepas concholepas (Bruguiere, 1789) that had been deposited in a continuous-flow aquarium at the Estacion de Biologia Marina Abate Juan Ignacio Molina, of the Universidad Catolica de la Santisima Conception, Chile, were kept in jars in aerated seawater at 14 [degrees]C, at the Campus San Andres of the same university, where veligers hatched over several days.
Gastropods mollusks (Gastropoda) the most numerous class in the Mollusca type (Linnaeus, 1758), which has about 60.000-75.000 species (Zhadin, 1926).
For some gastropod species, especially those without coiled shells, internally formed growth lines may be deposited with an annual periodicity.
Selection for prey shell thickness by the naticid gastropod Euspira lewisii (Naticidae) on the bivalve Protothaca staminea (Veneridae).
2004), and is the only land gastropod known that deliberately enters water, surviving for days while submerged in inundated areas.
The biodiversity of marine organisms have been regularly monitored to study the climatic changes and pollution impacts [45].The marine gastropod are exploited for food, at the same time the beautiful shape and colour of the shells have attracted and aroused the imagination of man to use them for ornamental purpose also[52].Mehmaz et al [29] reported that trawling is believed to affect the stock abundances directly by removing or killing individuals.
From gastropod examples: Trochus, Clanculus, Planaxis, Natica, Conus, Thais and Siphonaria.
In the deer's abomasum, or fourth stomach compartment, the gastropod releases infective larvae that migrate to the deer's spinal cord and brain, where they develop into mature egg-laying worms.
Physa populations lived in synthetic spring water (US EPA, 2002) in aquaria (gastropod density <1.5 individuals/liter) at 22 C 3 C with a 16:8 h light:dark photoperiod and received boiled spinach ad libitum, which decomposed and provided bacteria for gastropods to graze on, similar to periphyton (Warner, 1976).