title: Size Matters: Observed and Modeled Camouflage Response of European Cuttlefish (Sepia officinalis) to Different Substrate Patch Sizes during Movement.
abstract: Camouflage is common throughout the phylogenetic tree and is largely used to minimize detection by predator or prey. Cephalopods, and in particularSepia officinaliscuttlefish, are common models for camouflage studies. Predator avoidance behavior is particularly important in this group of soft-bodied animals that lack significant physical defenses. While previous studies have suggested that immobile cephalopods selectively camouflage to objects in their immediate surroundings, the camouflage characteristics of cuttlefish during movement are largely unknown. In a heterogenic environment, the visual background and substrate feature changes quickly as the animal swim across it, wherein substrate patch is a distinctive and high contrast patch of substrate in the animal's trajectory. In the current study, we examine the effect of substrate patch size on cuttlefish camouflage, and specifically the minimal size of an object for eliciting intensity matching response while moving. Our results indicated that substrate patch size has a positive effect on animal's reflectance change, and that the threshold patch size resulting in camouflage response falls between 10 and 19 cm (width). These observations suggest that the animal's length (7.2-12.3 cm mantle length in our case) serves as a possible threshold filter below which objects are considered irrelevant for camouflage, reducing the frequency of reflectance changes-which may lead to detection. Accordingly, we have constructed a computational model capturing the main features of the observed camouflaging behavior, provided for cephalopod camouflage during movement.
authors.affiliation: Mote Marine Laboratory, Directorate of Marine Biology and ConservationSarasota, FL, USA; Institute for Human and Machine CognitionPensacola, FL, USA.
authors.forename: Noam
authors.initials: N
authors.lastname: Josef
authors.affiliation: Eilat Campus, Department of Life Sciences, Ben-Gurion University of the NegevBeer Sheva, Israel; H. Steinitz Marine Biology Laboratory, Interuniversity Institute for Marine SciencesEilat, Israel.
authors.forename: Igal
authors.initials: I
authors.lastname: Berenshtein
authors.affiliation: Eilat Campus, Department of Life Sciences, Ben-Gurion University of the NegevBeer Sheva, Israel; H. Steinitz Marine Biology Laboratory, Interuniversity Institute for Marine SciencesEilat, Israel.
authors.forename: Meghan
authors.initials: M
authors.lastname: Rousseau
authors.affiliation: Eilat Campus, Department of Life Sciences, Ben-Gurion University of the Negev Beer Sheva, Israel.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Scata
authors.affiliation: Stazione Zoologica Anton Dohrn Napoli, Italy.
authors.forename: Graziano
authors.initials: G
authors.lastname: Fiorito
authors.affiliation: Eilat Campus, Department of Life Sciences, Ben-Gurion University of the Negev Beer Sheva, Israel.
authors.forename: Nadav
authors.initials: N
authors.lastname: Shashar
keywords: background matching; behavior; camouflage modeling; cephalopods; cognition; crypsis; object size recognition; vision