Ontogeny

Camouflage Pattern

            Cuttlefish use polarization throughout their lifespan as means of camouflaging; however, the ability to camouflage oneself changes over time to adapt to new goals[5]. As juveniles cuttlefish use camouflage to avoid predation from sharks, larger fish, and even other cuttlefish. When the cuttlefish has matured to adult hood and is ready to reproduce the ability to camouflage is often re-appropriated for attracting a mate [4][7].

            Cuttlefish also experience a change in their ability or propensity to exhibit certain polarization patterns. This is mainly due to growth in body mass as a cuttlefish ages.  Take for instance a substrate made up of tiny pebbles; a juvenile cuttlefish that is still small in area will choose a different camouflage pattern that it’s older counterpart simply because when placed against the substrate the smaller cuttlefish covers less pebbles and is thus more prone to matching the pattern on each individual pebble rather than the pebbles as a whole [1].

            For a more detailed example we can look to the study by Barbosa et al. Here, the researchers placed different aged cuttlefish against the same background and observed the cephalopods tendencies to exhibit say a mottled pattern over universally stippled, a phenomenon often predicted by their age [1].   

Figure 1. Barbosa et al. experiment showing camouflage differentiation between ages. Cuttlefish 1 is young, 4 is juvenile, and 6 is adult. The percentages represent the area of the cuttlefish as a portion of the area of the checker squares [1].

 

Cell Growth

It should also be noted the change in mechanistic structures. As a hatchling chromatophores are densely arranged in patterns similar to those found in adult cuttlefish; however, as they age more chromatophore density lessens dropping from around 500 chromatophore per square millimeter to anywhere around 35 per square millimeter. It should be acknowledged that though there is a significant decrease in density of chromatophores this does not necessarily mean a decrease in the cells themselves [7]. Rather it speaks to the enormous growth in area these organisms undergo over their lifetime. This change in cell density could partially account for a cuttlefish’s ability to exhibit different patterns as the cuttlefish grows. Hatchlings also exhibit few sparsely placed iridiphores and entirely lack leucaphores; obviously as the cuttlefish begins to mature it develops these cells, another ontogenetic change that could contribute to shifts in camouflage technique.