Color vision in the common octopus (Octopus vulgaris)

• Applicant: Professorin Dr. Frederike Diana Hanke
• Subject Area: Sensory and Behavioural Biology
• Term: from 2018 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 394412200

Cephalopods are molluscs that characterize themselves by their ability to adapt to the background termed camouflage. Camouflage does not seem to be based on a well-developed ability to perceive colors, a mystery that has been examined repeatedly during the last century. Previous studies on color vision in cephalopods, which also show methodological limitations, have led to contradictory results. Generally, the fact that most cephalopods only possess one photoreceptor type, they are monochromats, is well-established. In 2016, Stubbs and Stubbs postulated a mechanism that would allow monochromats to perceive color. This mechanism is based on chromatic aberration which is defined as the lens refracting light of different wavelengths differently. By actively changing focus, spectral information can be obtained from the variation of the blur of the image. The off-axis pupil of the cephalopods increases the chromatic blur that carries the color information in this specific color vision mechanism. The studies proposed in this research proposal are designed to test this color vision mechanism in a behavioral experiment in a cephalopod, the common octopus (Octopus vulgaris). Here for, some fundamental characteristics of the visual system of this cephalopod species need to be determined: (1) general eye morphology (magnetic resonance imaging), (2) pupil reaction, (3) optical properties of the lens (Schlieren photography, laser scan), and (4) brightness discrimination threshold (behavioral experiment). Altogether, these studies will contribute to a fundamental understanding of the visual system systematically obtained in one cephalopod species and can end the long lasting debate on color vision in octopus and can add to a new mechanism to perceive colors.

• DFG Programme: Research Fellowships
• International Connection: Sweden
• Host: Professorin Dr. Almut Kelber