Science Focus (issue 022)

h a s h a d a profound impact o n n e u r o s c i e n c e , uncovering the fundamental basis of how information flows in the nerve, as well as kickstarting the study of the role of ion channels in the process [4, 5]. Further investigations were also conducted by administer ing channel blockers (inhibitors) to modify the impulse. Further investigations revealed the involvement of additional ions that contribute to signal transmission in axons. [7]. Without a shadow of a doubt, the sacrifice of cephalopods has an undeniable significance in our quest for knowledge, especially in our comprehension of the nervous system. Marine Organisms Are More Than Seafood In the hi stor y of scient i f ic research, mar ine organisms have been extensively studied to elucidate biological phenomena and structural designs. Apart from cephalopods, sea urchins have been used to study developmental biology, revealing the roles of different proteins in cell cycle progression, while sea slugs gave us a glimpse into how memory works. If you have the chance to interact with these friends of ours, what would you do? 1 Delayed gratification: A subject studied extensively in psychology, defined as “the ability to either forgo immediate temptation or to persist in an undesirable activity, in order to reach a later goal [8].” 2 Editor’s remark: If you are interested in how neurons fire a nerve impulse, you may search “action potential” on YouTube. The mechanism is covered in first-year biology and was once a topic in the abolished HKALE. 頭足類動物 「花椒、鹽、五香粉。把調味料磨碎,放進碗裡。粟粉。 魷魚切花,這有助嫩化肉質。切開。把觸鬚 切成一半放進調味料裡。現在我們準備好 烹調了。」在 Gordon Ramsay 示範如 何烹調出一道令人垂涎的脆炸椒鹽鮮 魷的同時,你有沒有想過魷魚等頭 A diagram showing the difference in sodium ion (yellow) concentration across the membrane of an axon, the long projection that extends from a neuron, which is responsible for communication between neurons. 上圖展示軸突細胞膜兩側的鈉離子(黃)濃度差。軸突是神經元向 外延展的細長結構,負責神經元之間的溝通。 足類動物本身也是一個絕佳的實驗研究對象? 頭足類動物的英文「cephalopod」在希臘文上有著「頭 足」(cephalo-pod)的意思,顧名思義,這類動物的特徵 是觸手附在頭部。頭足綱的成員包括魷魚、章魚、墨魚和鸚 鵡螺。牠們被受景仰,擁有「最聰明的無脊椎動物」及「外星 智慧生物」等稱號,亦有助我們了解高階認知能力的進化。 牠們的複雜行為無論在野外還是實驗室內都總讓我們 驚嘆不已。章魚可以從環境取得空間線索以協助辨認方向, 避免重複地在同一區域搜尋資源 [1]。墨魚有自我約束能 力,懂得克制自己的行動,面對眼前的誘惑亦能拒絕作出短 視的決定(註一),展示出具決策能力的跡象[2]。魷魚能迅 速對威脅作出反應,噴出推進力強的水流敏捷地逃走 [3]。 在爭奪配偶上,雄性墨魚有與競爭對手展開肉搏戰的能 力,牠們會互相推撞和啃咬對方;不過善戰的墨魚有時 還是會按照情況用上其他策略,例如趁其他雄性沒 有留意的情況下,溜到躲在一旁的雌性身邊與其交 配,智取而不力敵 [1]。 除了令人印象深刻的行為外,牠們複雜的 皮膚擁有能改變顏色、圖案和質感的特性,