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標題: 虎斑烏賊攻擊腕吸盤之脫離過程及其對吸附表現的影響
Effects of detachment process on suction performance of the tentacular suckers in cuttlefish Sepia pharaonis
作者: 林殿昀
Tien-Yun Lin
關鍵字: 虎斑烏賊
Sepia pharaonis
sucker ring
摘要: 附著對生物而言是重要的功能,許多生活在水中的生物運用吸盤作為附著構造,來固定位置、移動、或補食。雖然都屬使用吸盤附著的頭足動物,但烏賊與章魚的吸盤在構造、作用機制、捕食行為及獵物種類都不同,烏賊使用一對能快速伸長的攻擊腕及其末端的吸盤來捕捉獵物。前人研究認為烏賊的吸盤屬被動機制,透過肌肉柄、肌肉壁、與吸盤環來分別達成力的傳遞、吸盤與表面密封、及維持吸盤形狀等功能,以產生吸附力。雖然吸附力產生的機制已被探討,但對於從吸附到脫離的過程,以及最後脫離的原因仍沒有進一步的了解。為探究此課題,我測量吸盤吸附力及形變量,並同步紀錄吸盤接觸面形變以及盤內氣泡的影像。比對可觀察到的現象,以及吸附力、吸盤內外壓力差、氣體壓縮率等數據,發現吸盤內產生的氣泡對其吸附力與形變量的關係曲線有明顯的影響。因氣泡比液體更容易被拉伸或壓縮,因此氣泡的體積改變減緩了吸盤腔內的壓力變化。我更進一步加入吸附表面之表面粗糙度、內鑲吸盤環等額外操作,發現吸盤的吸附力的表現並未因此出現顯著差異。我推測吸盤脫離的原因可能有吸盤結構受損、無法維持密封、及超越水分子內聚力等三種可能。觀察吸盤環在吸附到脫離過程中的橢圓度變化,吸盤環未產生永久形變,因此推測吸盤結構破壞非脫離原因。氣穴現象雖使吸盤內出現短暫的真空並產生氣泡,但發生時機早於吸盤脫離,因此非脫離原因,甚至還發現氣泡的產生可能延後脫離。而在吸盤受拉過程中,肌肉的垂直拉伸會造成吸盤接觸面與吸附表面間的相互滑動,終至彼此無法相互接觸、繼續維持密封而使吸盤脫離。從結果來看,虎斑烏賊攻擊腕的吸盤設計有利於其捕食策略,雖常見的人工吸盤在設計上有著和烏賊吸盤類似的結構,但能在粗糙、彎曲、甚至軟質表面上吸附的烏賊吸盤,能進一步作為仿生水下附著裝置的設計靈感來源。
Attachment plays an important role in living of creatures. Many aquatic animals use suckers for attachment during maintaining position, movement, or predation. Both octopus and cuttlefish are cephalopods using suckers for attachment, but their suckers are different in structure, functioning mechanism, predation behavior, and prey type. Unlike octopus, cuttlefish reach the prey by fast striking of two tentacles and capture it with suckers on the clubs. The cuttlefish suckers do not require muscle contraction to function, therefore are believed to work by passive mechanism. The muscular stalk, suction cup wall, and sucker ring have been proposed for transmitting force, sealing with the substrate, and maintaining contact shape, which are the three major components of suction. Although the functioning mechanism of suckers has been studied, but the attachment-detachment processes and the cause of detaching have never been examined. To this end, I measured the suction force and deformation of tentacular suckers in cuttlefish Sepia pharaonis, and synchronously filmed the shape change of the contact interface. Comparison of the suction force, pressure difference, and compressibility reveals that the bubbles appeared within the suckers obviously changed the force-deformation curve during the attachment-detachment process. Because gas deforms more easily than the liquid, the expansion of the bubbles would retard the increase of pressure difference. Furthermore, I found that the suction force of suckers would not be affected by the substrate roughness and insertion of a PVC ring. My results suggest that the causes of detachment might not be damage of the sucker structure or breakdown of water cohesion, but failure of sealing due to deformation of sucker muscles. When the extension reaches its limit, the suckers would unseal and detach from the substrate. Such mechanical features of tentacular suckers fit cuttlefish's predation strategy in capturing fast-moving preys. Although similar structures are common in artificial suckers, cuttlefish suckers perform well on rough, curved, or even soft surfaces, which provide insights for future bio-inspired design of underwater attachment devices.
文章公開時間: 2021-08-29
Appears in Collections:生物物理學研究所



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