Visual Stimuli for the Induction of Hunting Behavior in Cuttlefish Sepia pharaonis

Switching by cuttlefish of preying tactics targeted at moving prey

Previous studies have demonstrated that the size of the prey relative to the cuttlefish is important to the choice between tentacular strike and jump-on tactics. In the present study, we investigated the decision-making in the cuttlefish's tactical switch when preying on the same size prey. A servomotor system controlling the movement of a shrimp was used to elicit the cuttlefish's preying behavior. The success rate of prey capture and the kinematics of visual attack were examined systematically. The results showed that the jump-on behavior appeared mostly after a miss attack by previous tentacular strike on a moving shrimp. Compared with a visual attack with tentacles, the jump-on tactic has over a shorter attacking distance and wider attacking angles. Thus, these two different preying tactics have different operating ranges relative to the prey. More importantly, the cuttlefish can adjust their preying tactics adaptively depending on their prior preying experience.

Evaluation of Visual and Tactile Perception by Plain-Body Octopus (Callistoctopus aspilosomatis) of Prey-Like Objects

We investigated the characteristic features of perception in octopuses by examining multisensory information from an object simulating prey, which provided different visual and tactile stimuli. In experiments, we presented plain-body octopus with four kinds of models, namely, the Lifelike crab, the Embedded crab, the Translucent crab, and the Black cuboid. These models contain different amounts of visual and tactile information that a crab originally contains: the Lifelike crab resembles a crab both visually and tactilely, the Embedded crab resembles a crab visually but provides different tactile information, the Translucent crab provides tactile information of a crab but contains less visual information, and the Black cuboid lacks both visual and tactile information of a crab. Among these four models, octopuses contacted most with the Lifelike crab, which was similar to their behavior with a crab. Indeed, octopuses were fastest to contact the Lifelike crab and had the longest duration of contacting it among the four models. Octopuses contacted the Embedded crab more than the Translucent crab, both of which had contrasting visuo-tactile information compared to that of a crab. Quickness of octopuses to contact and duration of contact with the Embedded crab were more similar to those with the Lifelike crab than to those with the Translucent crab. Furthermore, octopuses contacted the Black cuboid least among the models. These results suggest that octopuses compositely detect both visual and tactile information in order to perceive an object. Furthermore, octopuses possess the potential priority either for visual or tactile information, by which they process the target object.

Potential evidence of peripheral learning and memory in the arms of dwarf cuttlefish, Sepia bandensis

CREB (cAMP response element-binding) transcription factors are conserved markers of memory formation in the brain and peripheral circuits. We provide immunohistochemical evidence of CREB phosphorylation in the dwarf cuttlefish, Sepia bandensis, following the inaccessible prey (IP) memory experiment. During the IP experiment, cuttlefish are shown prey enclosed in a transparent tube, and tentacle strikes against the tube decrease over time as the cuttlefish learns the prey is inaccessible. The cues driving IP learning are unclear but may include sensory inputs from arms touching the tube. The neural activity marker, anti-phospho-CREB (anti-pCREB) was used to determine whether IP training stimulated cuttlefish arm sensory neurons. pCREB immunoreactivity occurred along the oral surface of the arms, including the suckers and epithelial folds surrounding the suckers. pCREB increased in the epithelial folds and suckers of trained cuttlefish. We found differential pCREB immunoreactivity along the distal-proximal axis of trained arms, with pCREB concentrated distally. Unequal CREB phosphorylation occurred among the 4 trained arm pairs, with arm pairs 1 and 2 containing more pCREB. The resulting patterns of pCREB in trained arms suggest that the arms obtain cues that may be salient for learning and memory of the IP experiment.

Evidence of learning and memory in the juvenile dwarf cuttlefish Sepia bandensis

Measuring behavior in the form of numerical data is difficult, especially for studies involving complex actions. DanioVision is a closed-chamber system that utilizes subject tracking to comprehensively record behavior, while also mitigating the influence of environmental conditions. We used DanioVision to record activity of juvenile dwarf cuttlefish (Sepia bandensis) during the inaccessible prey (IP) procedure, a memory experiment in which cuttlefish learn to inhibit capture attempts towards inaccessible prey. By quantifying total movement and orientation of the body, we found that cuttlefish show memory by selectively inhibiting tentacle strikes without reducing total movement, or orientation towards the prey. We show that DanioVision can be used to assess multiple components of dynamic responses that are not measurable by direct observation alone and provide new evidence that strike inhibition is the product of learning, and not motor fatigue.