Locomotion byAbdopus aculeatus(Cephalopoda: Octopodidae):walking the line between primary and secondary defenses

Abstract

SUMMARY Speeds and variation in body form during crawling, bipedal walking,swimming and jetting by the shallow-water octopus Abdopus aculeatuswere compared to explore possible interactions between defense behaviors and biomechanics of these multi-limbed organisms. General body postures and patterns were more complex and varied during the slow mode of crawling than during fast escape maneuvers such as swimming and jetting. These results may reflect a trade-off between predator deception and speed, or simply a need to reduce drag during jet-propelled locomotion. Octopuses swam faster when dorsoventrally compressed, a form that may generate lift, than when swimming in the head-raised posture. Bipedal locomotion proceeded as fast as swimming and can be considered a form of fast escape (secondary defense) that also incorporates elements of crypsis and polyphenism (primary defenses). Body postures during walking suggested the use of both static and dynamic stability. Absolute speed was not correlated with body mass in any mode. Based on these findings the implications for defense behaviors such as escape from predation, aggression, and `flatfish mimicry' performed by A. aculeatus and other octopuses are discussed.

Ultra-fast escape of a deformable jet-propelled body

“…Longitudinal muscles prevent the elongation of the mantle as the radial muscles pressurize the mantle cavity. Maximum jetting speeds are reported to be 3.29 body lengths per s for mantle length of 45 mm in Huffard (2006). In addition, medusoid jetting may occur, when the octopus opens Ultra-fast escape of a deformable jet-propelled body 369 and then closes its arms and arm crown like an umbrella to aid jet propulsion (Huffard 2006).…”

“…Maximum jetting speeds are reported to be 3.29 body lengths per s for mantle length of 45 mm in Huffard (2006). In addition, medusoid jetting may occur, when the octopus opens Ultra-fast escape of a deformable jet-propelled body 369 and then closes its arms and arm crown like an umbrella to aid jet propulsion (Huffard 2006). Interestingly, the relatively bluff initial shape of cephalopods does not prevent them from achieving impressive velocities and bursts of acceleration.…”

Defensive Responses of Cuttlefish to Different Teleost Predators

“…Extant species within this taxonomic group are soft-bodied and lack morphological structures such as shells or spines, which are common defenses in other prey animals (vertebrates, e.g., fish; invertebrates, e.g., snails, sea urchins) and increase protection by making them more difficult to capture and ingest. This vulnerability may have influenced selective forces leading to the evolution of complex behaviors in coleoid cephalopods; these behaviors consist of chromatic, textural, postural, and locomotor components, and are involved in the signaling or avoidance of predators and conspecifics (Packard, 1972;Messenger, 1988, 1996;Huffard, 2006;Wood et al, 2008;Mäthger et al, 2012).…”

Shape of retracting foils that model morphing bodies controls shed energy and wake structure

“…Bats employ flexible, shape-and areachanging wings (Hedenstrom et al 2006;Lindhe Norberg & Winter 2006;Wolf et al 2010). Squid and octopus employ large volume and shape deformations to power their locomotion and maneuvering (Huffard 2006;Packard 1969;Muller & Lentink 2004;Polet et al 2015). Rowing involves imparting momentum to the fluid through motion of the oars, which are then retracted leaving an energetic wake behind; likewise insects and lizards can walk on water by submerging and then retracting their legs (Dickinson 2003;Hsieh & Lauder 2004;Hu & Bush 2010).…”