[5] The arms are 3.5 to 4.5 times the length of the mantle, and have two rows of suckers each.

C. rapanui is cream-gray with a darker purple hue on its dorsal surfaces.

[6] Its most distinctive feature is a "straight, out-turned" rostrum.

[7] Callistoctopus rapanui is subtropical[1] and only known in Rapa Nui.

[6] It is benthic,[1] and found at depths of zero to four metres (0 to 13 ft).