The feeding mechanism of the oyster. I. On the pallium and the branchial chambers of Ostrea virginica, O. Edulis and O. Angulata, with comparisons with other species of the genus

Abstract

TWENTY-ONE FIGURES AUTHOR'S ABSTRACTSeparation of the inantle from the visreral mass on the right side in deeply cupped species of oyster provides a shorter channel for egress of water from the right demihranchs. Correlated with this change is reduction in size of the right epihranchial chamber beneath the adductor together wilh backward displacement of the adductor itself. This water passage, designated the promyal chamber develops during the first week after attachment of the oyster larva. The grealest displacement of the adductor and the largest promyal chamber occur in 0. frons. The mantle border shows three reduplications of which the innermost, the pallial curt,ain controls the amount and the place of entrance and egress of water. The importance of 'pallial curtains and promyal chamber to survival in turhid waters is discussed : oysters with the promyal chamber have invaded the river mouths, the flat oysters without this chamber have remained in the rlear waters of high salinity near the sea. The bearing of these factors on the disappearance of fossil oysters is considered. I t is proposed to relate to the genus Ostrea all flat, larviparous oysters which lack the promyal chamber and to raise the subgenus Gryphaea to generic r a n k to inrlnde all deeply cupped oviparous oysters with the promyal rharnher.Anatomical and histologiral features of the pallium and hranchial chambers are (.onsidered in detail.

The Anatomy of the Pacific Oyster, Crassostrea gigas (Thurnberg)(Bivalvia : Ostreidae)

“…The evaluation of internal organ features in interspecific comparison has been attempted in genera Ostrea, Saccostrea, Hyotissa, Crassostrea and Dendostrea (Harry, 1985;Li & Qi, 1994). Based on the results of this study and those of previous studies (Nelson, 1938(Nelson, , 1960Torigoe, 1981;Harry, 1985;Li & Qi, 1994), the anatomical features of the soft organs that can be used to distinguished oyster species within and between genera are: length of epibranchial septa, morpho-sculptural characters of labial palp crests, topography of diverticular openings, configuration of digestive embayments, outlines of caeca, morphology of oesophageal aperture, features of ventricle and auricles, and branches of accessory hearts.…”

“…However, some distinctions in the mantle features of these species have been found. For example, in contrast to C. virginica the posterior portion of the right epibranchial cavity in C. angulata is constricted as a result of the extension of the right septum (Nelson, 1938). These peculiarities in septa were considered by Harry (1985) as the supra-specific characteristics in Ostreidae, and were reconfirmed by Li (1989) for their taxonomic importance in species comparison.…”

“…For example, C. virginica has 8-15 (mean 12); C. angulata has 8-14 (mean 12) (N eslon, 1960), the average numebr in C. gigas is 12. Differences can also be found in the arrangements of the interlamellar septa, which are at 4 plica intervals in C. virginica, 6 in C. angulata (Nelson, 1938(Nelson, , 1960, and 5 in C. gigas.…”

“…The importance and usefulness of the internal organ features in oyster taxonomy have been known for more than 50 years (Orton, 1937;Nelson, 1938), and have been stressed in recent works (Torigoe, 1981;Harry, 1985;Li & Qi, 1994). In addition to the shell morphology and the shell structures, the features usually used to identify genus are: types of early larval development, presence of promyal passage, morphological features of mantle margins, configuration and structure of sorting crests of labial palps, relationships between labial palps and gills, connection between crystalline style sac and midgut, numbers of ordinary filaments per branchial plicae, general morphology of stomach, positions of diverticular chambers, and situations of appendix and typhlosole.…”

“…For example, Pelseneer (1903) found that the structure of branchiae and other soft organ characteristics could be used to separate bivalve classes. Nelson (1938Nelson ( , 1960 found that differences in the structure of the promyal chamber and labial palp morphology could be used to identify oyster species of the genus Ostrea.…”