Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN 55108, USA.
Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN 55108, USA; Department of Biomedical Informatics and Computational Biology, University of Minnesota, Minneapolis, MN 55455, USA.
Curr Biol. 2022 Nov 7;32(21):4727-4733.e3. doi: 10.1016/j.cub.2022.08.080. Epub 2022 Sep 20.
Octopus' limb hyper-redundancy complicates traditional motor control system theory due to its extensive sensory inputs, subsequent decision-making, and arm coordination. Octopuses are thought to reduce flexibility control complexity by relying on highly stereotypical motor primitives (e.g., reaching and crawling) and multi-level processes to coordinate movement, utilizing extensive peripheral nervous system (PNS) processing. Division of labor along the anterior-posterior axis and limb specialization of the four anterior arms in T-maze food retrieval further simplify control. However, specific arm recruitment and coordination during visually guided reaching behavior remains poorly understood. Here, we investigated visually evoked Octopus bimaculoides' prey capture capabilities by eliciting and examining prey-specific arm recruitment. When striking crabs, octopuses preferred synchronous arm recruitment, while sequential arm recruitment with a characteristic swaying movement is employed for shrimp. Such behavioral selection aligns with specific prey escape strategies and the octopus' flexible arm biomechanical constraints. Although side bias existed, we found significant bilateral symmetry, with one side being functionally a mirror of the other rather than anterior arm use being functionally equal and differing to posterior arm use. Among arms, the second limb is unequivocally dominant for goal-directed monocularly driven prey capture. Although the eight arms share gross anatomy and are considered equipotential, such arm use for specific actions could reflect subtle evolutionary adaptations. Finally, we quantitatively show, corroborating earlier observations, that octopuses employ a dimension reduction strategy by actively deciding to recruit adjacent arms over other available arms during either sequential or synchronous visually evoked prey attack.
章鱼的肢体高度冗余，其广泛的感觉输入、随后的决策和手臂协调使得传统的运动控制系统理论变得复杂。章鱼被认为通过依赖高度刻板的运动原语（例如，伸展和爬行）和多层次的过程来协调运动，并利用广泛的周围神经系统（PNS）处理来减少灵活性控制的复杂性。在 T 形迷宫食物检索中，沿前后轴的分工和四个前肢的专业化进一步简化了控制。然而，在视觉引导的伸展行为中，特定手臂的募集和协调仍然知之甚少。在这里，我们通过引发和检查特定于猎物的手臂募集来研究视觉诱发的章鱼二斑蛸的猎物捕获能力。当攻击螃蟹时，章鱼更喜欢同步手臂募集，而对于虾，则采用具有特征性摇摆运动的顺序手臂募集。这种行为选择与特定猎物的逃避策略和章鱼灵活的手臂生物力学限制相一致。尽管存在侧偏，但我们发现了显著的双侧对称性，一侧在功能上是另一侧的镜像，而不是前肢的使用在功能上是相等的，并且与后肢的使用不同。在手臂中，第二只手臂在有目的的单眼驱动猎物捕获中具有明确的主导地位。尽管这 8 条手臂具有大体解剖结构，被认为具有同等潜力，但对于特定动作的手臂使用可能反映了微妙的进化适应。最后，我们定量地表明，章鱼通过积极决定在顺序或同步视觉诱发的猎物攻击期间招募相邻手臂而不是其他可用手臂，从而采用了一种维度减少策略，这与早期的观察结果相吻合。
