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Full-Text Articles in Life Sciences
The Orientation Of Strophomenid Brachiopods On Soft Substrates, Roy Plotnick, Benjamin Dattilo, Daniel Piquard, Jennifer Bauer, Joshua Corrie
The Orientation Of Strophomenid Brachiopods On Soft Substrates, Roy Plotnick, Benjamin Dattilo, Daniel Piquard, Jennifer Bauer, Joshua Corrie
Benjamin F. Dattilo
Strophomenid brachiopods have long been interpreted as ‘‘snowshoe’’ strategists, with their flattened concavoconvex valves providing resistance to foundering in very soft sediments. There has been a sharp difference of opinion in whether the shells were oriented with their convex or their concave surface in contact with the sediment. This study, along with independent evidence from sedimentology, ichnology, and morphology, indicates that the strophomenids lived with their shells concave down (convex up). Experiments indicate the force required to push shells into soft cohesive muds is much greater for the convex up than for the convex down orientation. Forces also increase with …
Uptake Of Dissolved Free Amino Acids By Northern Quahogs, Mercenaria Mercenaria, And Its Relative Importance To Organic Nitrogen Deposition In Narragansett Bay, Rhode Island, Michael A. Rice
Michael A Rice
Studies were undertaken to determine the relationship between size of northern quahogs Mercenaria mercenaria and the rate at which they transport aspartic acid. Quahogs ranging from 25 to 103 mm valve length were collected in Narragansett Bay and placed in seawater aquaria (27 ppt, 20 deg C) and allowed to pump actively. Uptake experiments were carried out using 1 umol/L C(14) radiolabeled aspartic acid. Aspartate transport rates in umol/h can be related to valve length by the allometric equation with a = 24.32 and b = 0.905 when valve length is in mm. In May 1990, near bottom samples of …