Why do Univalve Shells of Gastropods Coil so Tightly? A Head-Foot Guidance Model of Shell Growth and its Implication on Developmental Constraints
Tight coiling with whorl overlap is the most frequent mode of shell coiling in gastropods. A new model of shell growth, the “head-foot guidance model”, implies that the contact of the head-foot mass with the mantle edge plays the main role in producing tight coiling. Computer simulation of the model suggests that the head-foot guidance mechanism imposes developmental constraints on the evolution of gastropods; 1.) bilaterally symmetric coiling is associated with bilaterally symmetric musculature of the foot mass; 2) tight coiling is associated with the contact of the head-foot mass and the mantle edge; 3) insertion of the foot muscle occurs in gastropods with an uncoiled shell.
KeywordsContact Pressure Shell Growth Developmental Constraint Univalve Shell Life Position
Unable to display preview. Download preview PDF.
- 2.Hickman, C.S. (1993). Theoretical design space: A new program for the analysis’ of structural diversity. N.Jb.Geol.Palaeont, Abh., 190 (2/3), 169–182.Google Scholar
- 6.Morita, R. (1993). Developmental mechanics of retractor muscles and the “dead spiral model” in gastropod shell morphogenesis. N. Jb. Geol. Palaeont. Abh., 190 (2/3), 191–217.Google Scholar
- 7.Raup, D. M. (1966). Geometric analysis of shell coiling: general problems. J. Paleontology, 40 (5), 1178–1190.Google Scholar