Data Sheet 1_Environmental control of morphological color changes in the Bigfin Reef Squid, Sepioteuthis lessoniana.pdf

Black-reared squid maintained higher numbers of black chromatophores, whereas white-reared squid exhibited fewer but generally larger black chromatophores at later developmental stages, revealing an inverse relationship between chromatophore number and size. Yellow chromatophore number also increased in black-reared squid during later development, while yellow and red chromatophore size showed environment-, age-, and region-specific responses.

Dorsoventral differences became increasingly pronounced with age, particularly through a decline in ventral black chromatophores, consistent with the development of countershading.</p>Discussion<p>These findings demonstrate that the cellular substrate underlying cephalopod color change is itself phenotypically plastic and is dynamically remodeled across development in response to sustained visual environments. The apparent tradeoff between chromatophore number and size suggests that different environments can produce distinct pigmentary architectures.

We propose that this slower morphological plasticity establishes a changing substrate upon which rapid neural control operates, potentially recalibrating the dynamic range of color change across development. Together, these results expand current frameworks of cephalopod coloration by integrating developmental, environmental, and cellular mechanisms across multiple timescales.</p>