REPLICATION OF SUBSTRATE DETAIL BY BARNACLES AND SOME OTHER MARINE ORGANISMS

¹ Department of Biology, Princeton University, Princeton, New Jersey

1. Barnacles of the species Balanus eburneus Gould were found to orient themselves with their long axes parallel to the grooves in the substrate, while oysters (Ostrea virginica Gmel.) were found to orient themselves at random.

2. The grooving in the substrate was found to affect the topography of the compartments and the basal plate of the barnacle Balanus eburneus Gould. The grooves are duplicated upon the compartments and the ridges upon the basal plate. Any one groove on the record causes a ridge to occur on the basal plate and a groove to appear on the compartments of the barnacle. These grooves and ridges are initiated at the early growth stages and persist irrespective of the ultimate size of the organism.

3. In a similar manner the grooved surface of the phonograph records affects the shells of the mollusc Ostrea virginica Gmel. both externally and internally by causing grooves and ridges to appear on the upper and lower shells.

4. The living species of barnacles, Balanus rostratus apertus Pilsbry, Balanus balanus Linnaeus (Pilsbry, 1916), Balanus porcatus DaCosta, Balanus crenatus Bruguiére, Balanus patellaris Spengler (Darwin, 1854), and the fossil barnacles Balanus shilohensis (Pilsbry) (Pilsbry, 1930) and Balanus concavus Bronn also have their compartments affected by the substrate to which they attach.

5. The mollusc Anomia simplex d'Orb may also exhibit characteristics of the surface to which it attaches.

6. The fossil brachiopods Crania scabiosa (Hall) [Petrocrania scabiosa (Hall)] (Hall, 1870), Philhedra mimetica Kozlowski (Kozlowski, 1929), Philhedra crenistriata (Hall) and the annelid tube of Cornulites proprius Hall (Hall, 1892) have been found to assume certain features of the substrate upon which they grew.

7. Grooving and ridging occur on the barnacle Balanus eburneus Gould because the shell building material secreted by the organism in maintaining close contact with the substrate is obliged to follow the contours of the surface. This close association during growth eventually leads to the formation of grooving on the compartments and ridging on the basal plate.

8. A similar explanation for the fact that young of the molluscs Ostrea virginica Gmel. and Anomia simplex d'Orb show ridging and grooving phenomena is offered, with the exception that the lower shell of a mollusc acts as the pattern to which the upper shell must conform during growth. This explanation is probably adequate for similar substrate reproduction by the brachiopods.

9. Variations in the normal length-width ratio of Balanus eburneus Gould result from growth upon a grooved surface. This was attributed to the fact that the compartments and the parts of the basal plate which must grow perpendicular to the grooves are retarded in the rate of increase in length or width in the plane of attachment.