Rate of Replacement of the Molluscan Radula

Runham, N. W.

doi:10.1038/194992b0

Cited by 41 publications

(29 citation statements)

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“…The loosening, collecting and tearing of ingesta leads to tooth wear (e.g. Runham, 1962 ; Runham and Thornton, 1967 ; Mackenstedt and Märkel, 1987 ; Shaw et al, 2010 ), but through a continuous growth of the radular ribbon from posterior to anterior, tooth rows constantly break loose and are replaced (e.g. Runham, 1962 ; Mackenstedt and Märkel, 1987 ).…”

Section: Introductionmentioning

confidence: 99%

Not just scratching the surface: Distinct radular motion patterns in Mollusca

et al. 2020

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The radula is the organ for mechanical food processing and an important autapomorphy of Mollusca. Its chitinous membrane, embedding small radular teeth, is moved by the set of muscles resulting in an interaction with the ingesta, tearing it and collecting loosened particles. Radulae and their teeth can be quite distinct in their morphology and had been of high research interest, but only few studies have examined the basic functional principles of this organ, the movement and motion during feeding action. Here, the radular motion of 20 representative species, belonging to four major gastropod lineages (Vetigastropoda, Neritimorpha, Caenogastropoda, Heterobranchia) and Polyplacophora, were recorded and classified. Comparisons of the video footage with the SEM images of the radula resulted in the recognition of functional tooth rows and the correct position of the teeth during feeding. We identified six different types of radular movements, including rotations and bending of the radula itself. In each movement type, different structures act as counter bearings enabling the animals to grab and tear food.

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Section: Introductionmentioning

confidence: 99%

Not just scratching the surface: Distinct radular motion patterns in Mollusca

et al. 2020

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“…Teeth are synthesized by microvillar secretion in the single studied patellid species Patella pellucida Linnaeus, 1758 (Peters, ) and several species of Heterobranchia (Hughes, ; Kerth, ; Mackenstedt & Märkel, ; Mikhlina et al, ; Wiesel & Peters, ). Two studied species of Caenogastropoda (Mischor & Märkel, ; Vortsepneva et al, ; see Table ) combine the apocrine and microvillar secretion during tooth formation. The tooth shape in T. testudinalis is not determined by microvilli as it was suggested for other gastropods (Runham, ; Wiesel & Peters, ), but by the localization of odontoblasts in the cushions. This is similar to the chaetae in Annelida, which are synthesized by special cells (chaetoblasts) due to microvillar secretion while the shape is determined by its surrounding cells (Bartholomaeus, ; Hausen, ; Kolbasova, Tzetlin, & Kupriyanova, ).…”

Section: Discussionmentioning

confidence: 77%

General morphology and ultrastructure of the radula of Testudinalia testudinalis (O. F. Müller, 1776) (Patellogastropoda, Gastropoda)

Vortsepneva

Tzetlin

2019

Journal of Morphology

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The radular morphology of the patellid species Testudinalia testudinalis (O. F. Müller, 1776) from the White Sea was studied using light, electron, and confocal microscopy.The radula is of the docoglossan type with four teeth per row and consisting of six zones. We characterize teeth formation in T. testidinalis as follows: one tooth is formed by numerous and extremely narrow odontoblasts through apocrine secretion; this initially formed tooth consists of numerous vesicles; the synthetic apparatus of the odontoblasts is localized in the apical and central parts of the cells throughout the cytoplasm and is penetrated by microtubules which are involved in the transport of the synthesized products to the apical part of the odontoblast; the newly formed teeth consist of unpolymerized chitin. Mitotic activity is located in the lateral parts of the formation zone. The first four rows contain an irregular arrangement of teeth, but the radular teeth are regularly arranged after the fifth row. The irregularly arranged teeth early on could be a consequence of the asynchronous formation of teeth and the distance between the odontoblasts and the membranoblasts. The morphological data obtained significantly expands our knowledge of the morphological diversity of the radula formation in Gastropoda. K E Y W O R D Sapocrine secretion, chitin, odontoblasts, radula formation, ultrastructure

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“…Indeed. this may have been their original purpose in N. atramentos(/, as they would rapidly be removed from the body through radula tooth turnover (Runham 1962). The need for such a mechanism may have arisen as a result of the diatom rich diet of N. atramento.1"ll (Underwood 1978).…”

Section: Discussionmentioning

confidence: 99%

Mineralisation in the teeth of the gastropod molluscNerita atramentosa

Macey

Brooker

Cameron³

1997

Molluscan Research

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The radula teeth of the littoral gastropod. Nerita atramentosa, have been analysed using energy dispersive spectrometry. The matrix of the mature major lateral teeth contains sulfur. chlorine. potassium. calcium and magnesium. The teeth are tanned. and additionally hardened by the possession of biomineralised granules which contain sulfur. chlorine and calcium. together with a large range of other elements including silicon. aluminium. titanium. chromium. iron. nickel. and manganese. These granules. which are incorporated into the matrix of the teeth. result in a surface comparable to sandpaper which presumably serves to increase the abrasive properties of the major laterals. In contrast. the marginal teeth. which are only used for sweeping food particles into the mouth. are not mineralised to the same extent and do not contain granules. This approach to the biomineralisation of their teeth may well have contributed to the competitive success of N. atrementosa in the littoral environment.

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Rate of Replacement of the Molluscan Radula

Cited by 41 publications

References 0 publications

Not just scratching the surface: Distinct radular motion patterns in Mollusca

Not just scratching the surface: Distinct radular motion patterns in Mollusca

General morphology and ultrastructure of the radula of Testudinalia testudinalis (O. F. Müller, 1776) (Patellogastropoda, Gastropoda)

Mineralisation in the teeth of the gastropod molluscNerita atramentosa

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