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Dryad

Videos used in creating ethograms for Callistoctopus furvus

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Dec 16, 2024 version files 712.47 KB
Feb 05, 2025 version files 759.36 KB

Abstract

Callistoctopus furvus (the “eastern” or “sand octopus”) is a relatively unstudied species of nocturnal medium-large octopus inhabiting shallow coastal areas of the tropical western Atlantic. To aid in field identification, promote further study of this species and enhance understanding of skin patterns and behavior of nocturnal shallow water octopuses, we composed an ethogram of C. furvus from photographs and 3.06 hrs of video collected of wild individuals in the natural environment. We cataloged three colors, 17 chromatic components, six groups of skin patterns (divided into 16 sub patterns), three textures, 10 postures and 12 behaviors. Photographs and videos of C. furvus from other geographic areas could be classified using this ethogram, supporting its validity for study of C. furvus throughout its geographic range. Nine features can be used to differentiate this species from co-occurring octopods through observation alone: the front four arms are larger than rear four arms, strict nocturnality, brick red incorporated into most skin patterns and rows of regularly spaced white spots that are always at least faintly visible on the arms, a polka dotted deimatic pattern, large “U”-shaped papillae on the mantle, six distinct mantle shapes, a shallow arm web, the execution of very few “parachute attacks” and a tendency to enter existing holes or bury itself in response to disturbance. Notable features include the use of at least one “dynamic” chromatic component, putative masquerade as algae, potential mimicry of trumpetfish or cornetfish and escape into either existing holes or by burying. Greater observation and study of C. furvus and other octopods from a diversity of habitats, latitudes and temporal niches will enhance understanding of how these factors have shaped the use of colors, body patterning and behavior of this unique group of molluscs.