Annual Report 2011–12

Pushing Knowledge Frontiers 27 尋找皇帝蟹的祖先 生命科學學院及李福善海洋科學研究中心 院長朱嘉濠教授，聯同由其指導修讀博士 課程的曾令銘博士、台灣海洋大學陳天任 教授，以及悉尼澳洲博物館的 Dr. Shane Ahyong ，根據 DNA 排序分析證實，皇帝蟹 其實是寄居蟹的近親，屬異尾類動物，而不 同於大閘蟹、青蟹和花蟹等螃蟹。 相較於真正的螃蟹，異尾類動物的最後一 對腳非常細小，而尾巴通常捲曲於身體之 下。寄居蟹和一些外形與蟹和龍蝦相似的 甲殼動物，如皇帝蟹、瓷蟹及鎧甲蝦，均屬 於異尾類動物。 朱教授等人的研究顯示，體重一般少於四 分之一磅的寄居蟹，不單是重量可逾十八 磅、兩腳張距可長達六呎的皇帝蟹的祖先， 更幾乎是所有異尾類的祖先。 動物外表相似並不一定代表它們有密切關 係。相近特徵通過個別演化可進化成不同 型態，這現象稱為平行演化，真正的蟹跟蟹 狀的異尾類如寄居蟹和皇帝蟹，便是平行 演化的例子。 這項發現已於 2011 年 8 月的《系統生物學》 上發表。 In Search of King Crab’s Ancestor Prof. Chu Ka-hou, director of the School of Life Sciences and Simon F.S. Li Marine Science Laboratory, worked in collaboration with his former PhD student Dr. Tsang Ling-ming, Prof. Chan Tin-yam from Taiwan Ocean University, and Dr. Shane Ahyong from the Australian Museum in Sydney. They confirmed that king crabs, scientifically speaking, are not really ‘crabs’, in the same way as are the Chinese mitten crabs, the common mud crabs and other swimming crabs. They are actually close relatives of the hermit crabs, and belong to a group known as the anomurans. Anomurans are a group of crustaceans that include hermit crabs and other forms that have a crab-like (such as king crabs and porcelain crabs) or lobster-like (called squat lobsters) appearance. Compared to true crabs, the last pair of legs of anomurans is very small and their tails are often folded under the body.
 Their study based on new evidence from DNA analysis shows that the tiny hermit crab, which generally weighs less than a quarter of a pound, is the ancestor of not only the king crab, a creature that may weigh more than 18 pounds with a limb span reaching six feet, but also that of almost all other anomurans. 
 朱嘉濠教授（左）及曾令銘博士展示皇帝蟹與寄居蟹在體積上的巨大差別 Prof. Chu Ka-hou (left) and Dr. Tsang Ling-ming show the dramatic difference in size between king crabs and hermit crabs 異尾類動物 Anomurans