106 Corethron criophilum 棘冠藻 Phylum: Heterokontophyta 门：不等鞭毛門 Class: Coscinodiscophyceae 纲：中心硅藻綱 Order: Corethrales 目：棘冠藻目 Family: Corethraceae 科：棘冠藻科 Morphology Cells are usually solitary, with pill-shaped, and weakly silicified frustules. Valves are circular, strongly convex, and display arched hemispherical shape in girdle view. The lengths of pervalvar axis are generally twice of valve diameters. A circle of long setae radiates outwards from the edge of both valves. The direction of two circles of setae between upper and lower valve is same or opposite depending on the stage of cell division. There is also a circle of short, hooked spines between the long one on the edge of one valve. Chloroplasts are small and numerous. 形態 細胞通常獨立生活，細胞壁膠囊形狀，硅質化較低。殼面圓，強烈凸起，從殼環面 觀看呈半球形。貫殼軸長度一般為直徑的兩倍。上下殼邊緣各生一圈長刺。上下殼 兩圈長刺的射向相同或相異，與細胞分裂狀態相關。其中一個殼面邊緣長刺之間還 有一圈短而彎曲的刺。色素體小而多。 Ecology and distribution Corethron criophilum is a cosmopolitan species in both coastal and oceanic waters. This species is widely distributed from polar region to tropical areas. 生態與分佈 棘冠藻是廣布性物種，近岸到大洋，熱帶到兩極均有分佈。
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