Month: September 2022

HANDEDNESS. "Most shells are right handed and possess overlapping whorls that coil around a single axis. Spiral coiling also appears to be dictated by a set of ‘behavioural’ rules involving shell sculpture ... Opisthostoma shells are 'sinistroid’ due to a reversal in coiling direction in the last half-whorl ... can possess two or three different coiling axes." https://lnkd.in/dNeQF-g View in LinkedIn

COILING FIXED. "Usually, the direction of coiling is the same for all members of a given species. Occasionally, though, mutants are found." https://lnkd.in/dctHRnB View in LinkedIn

COILING GENES. "The direction of snail shell coiling is controlled by a single pair of genes ... there is a right-coiling allele D, which is dominant to the left-coiling allele d ... However, the direction of cleavage is determined not by the genotype of the developing snail, but by the genotype of the snail's mother." https://lnkd.in/dctHRnB View in LinkedIn

"LOGARITHMIC COILING IN SHELLS was first mathematically described over a century ago, the developmental bases of these shell forms remains unknown. Similarly, the three-dimensional ornamentations on shells, which can be seen as a deviation from simple coiling, emerge through largely unknown processes." https://lnkd.in/dSJZzWB View in LinkedIn

"THE EVOLUTION OF A SHELL. In one process, the shell aperture undergoes coiling, dilation, translation, and rotation. these rates are highly controlled throughout the shell development, and the resulting shell form has the mathematical regularity." https://lnkd.in/dSJZzWB View in LinkedIn

"THE EVOLUTION OF A SHELL. In the second process, the aperture shape evolves, producing ornamentation such as ribs or spines on the shell surface." https://lnkd.in/dSJZzWB View in LinkedIn

MATHEMATATICIANS DESCRIBE BIOLOGY. "Biological morphogenesis is a mechanical pro- cess that connects genetic, molecular, and cellular activities with the macroscopic deformations shaping organisms. ... shell morphogenesis can be thought of as a trajectory unfolding in a shape space constrained by geometry and mechanics." https://lnkd.in/dSJZzWB View in LinkedIn

SHELL PATTERNS IN SPACE AND TIME. "The patterns on shells of molluscs show an overwhelming diversity. Very little is known about the biological basis of shell patterning." (1987). A beautifil theoretical analysis of the complex pattern motifs of some shells. http://www.eb.tuebingen.mpg.de/research/emeriti/hans-meinhardt/shells.html View in LinkedIn

NEURAL CONTROL. "Seashells display a remarkable variety of ornate pigmentation patterns ... shell growth and patterning are under neural control and that shell growth and pigmentation is a neurosecretory phenomenon." http://www.pnas.org/content/106/16/6837.full View in LinkedIn

EPISODIC CONSTRUCTION. "The shell is constructed by periodic—usually daily—bouts of secretion. Sensory organs in the mantle detect the presence of pigment and stimulate pigment secretion in local secretory cells." https://lnkd.in/dqhz3rW View in LinkedIn