Wikipedia:Picture of the day/January 13, 2007
Individuals in the mollusk species Donax variabilis show diverse coloration and patterning in their phenotypes. The phenotype of an individual organism is either its total physical appearance and constitution or a specific manifestation of a trait, such as size, eye color, or behavior that varies between individuals. Phenotype is determined to a large extent by genotype and influenced by environmental factors. Early geneticists were able to trace inheritance patterns without any knowledge of molecular biology.Photo credit: Debivort