On the underwater weights of freshwater snails

Henderson, A. E.

doi:10.1007/bf00340471

Cited by 10 publications

(6 citation statements)

References 9 publications

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“…This variation was of the same magnitude in the different partial tensions of the water being tested. This seems to be a universal feature in molluscs (Berg & Ockelman 1959;Prosser & Brown 1961;Ghiretti 1966;Henderson 1963). One explanation is that in pulmonate snails the air volume in the mantle cavity could change, thus indirectly affecting the oxygen exchange rate in the tissues.…”

Section: Oxygen Consumption Experiments Respirometer Measurementsmentioning

confidence: 99%

Oxygen consumption and responses of the freshwater snailBulinus(Physopsis) globosus to gradients of different oxygen tensions

Aardt

Frey

1979

South African Journal of Zoology

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A gradient or choice apparatus, based on the 'fluvarium' principle and suitable for testing the responses of the freshwater snail Bulinus (Physopsis) globosus to different partial oxygen tensions was used. In a gradual oxygen gradient established with this apparatus, B. (P.) globosus shows a significant preference for oxygenated water. In experiments with a choice between low and high partial oxygen tensions, B. (P.) globosus shows a greater preference for oxygenated water. Oxygen consumption rates vary considerably among individuals and decreases when lowering the Po 2 in the water.

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Section: Oxygen Consumption Experiments Respirometer Measurementsmentioning

confidence: 99%

Oxygen consumption and responses of the freshwater snailBulinus(Physopsis) globosus to gradients of different oxygen tensions

Aardt

Frey

1979

South African Journal of Zoology

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“…Planorbids have an air-filled pulmonary sac, which, according to several authors (Russell Hunter 1953;Jones 1961;Henderson 1963), serves as a hydrostatic apparatus. In fact, it can easily be observed that animals are able to sink or float and, in some species, to adjust the orientation of the shell with respect to the substrate while floating, presumably by varying the volume of air within the pulmonary sac.…”

Section: Natural Life Posture In Planorbidaementioning

confidence: 99%

Regulation of spiral growth in planorbid gastropods

Checa

Jiménez-Jiménez

1997

LET

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Extensive experimentation has been performed on the planorbid Planorbarius metidjensis in order to determine which mechanism allows the snail to coil its shell regularly. Individuals of this species, like all Planorbidae, are permanently active and secrete their shells while crawling on the substrate. Experiments consisted of attaching weights to either side of the shell (which is carried almost vertically) in an umbilical position; these weights cause the shell to fall towards the substrate on the loaded side. It can be demonstrated, qualitatively and quantitatively, that during further growth the shell tube deviated initially (i.e. within the first half whorl after loading) towards the loaded side. In a later stage, when the animal is able to re‐balance the shell‐load complex by muscular activity, the shell tube gradually deviates away from the loaded side. This behaviour is to be expected if, after loading, secretion of the shell continued with the aperture parallel to the substrate and forming a constant angle with the direction of growth. The main implication is that in normal conditions the living posture largely controls the correct coiling of the shell. Minor experiments made with another planorbid species, Gyraulus laevis, confirm these conclusions. The growth pattern of planorbids requires that the snail has constant information on the orientation of the shell with respect to the substrate. This is permitted by the particular physiological ecology of this group, members of which, unlike terrestrial gastropods, are permanently active.

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“…However, these investigators did not consider that water can circulate inside the mantle cavity. Henderson (1963) and Jones (1961), when analyzing the content of the air bubbles, stated that in P. corneus and L. stagnalis the bubble may function as a physical gill.…”

Section: Air and Water Inflow And Outflow In The Mantle Cavitymentioning

confidence: 99%

“…In this case, we cannot preferentially associate this type of respiration with the tegument or the pseudogill since both can function simultaneously; (3) there is the possibility that the air bubble, in addition to functioning as an oxygen reservoir and aiding flotation, may also function inside the mantle cavity as a physical gill since it may remove oxygen from water through nitrogen. This mechanism exists in some aquatic insects that submerge with an external bubble (Ege 1918) and has been attributed by Henderson (1963) to mol-lusks such as Planorbarius corneus and Lymnaea stagnalis; (4) water circulation inside the mantle cavity ) is another factor that impairs the characterization of the type of respiration.…”

mentioning

confidence: 99%