164 Chaetoceros 角毛藻 Phylum: Heterokontophyta 门：不等鞭毛門 Class: Mediophyceae 纲：中型硅藻綱 Order: Chaetocerotales 目：角毛藻目 Family: Chaetocerotaceae 科：角毛藻科 Morphology Cells are roughly short cylindrical, with heights (pervalvar axis) similar with widths (apical axis) or slightly smaller. Cells are roughly rectangular in girdle view and elliptical in valve view, with a few being nearly circular. Valves are flat, convex, or concave in center and two setae arise from the end of apical axis. Some species are solitary. For most species, adjacent cells are linked by the crossing or touching of the setae and form straight, curved, or spiral chains with different lengths. Terminal setae are thicker and shorter generally. Morphology, arising position and direction of setae are important to identify Chaetoceros species. Different species possess distinct apertures, including linear, dumbbell shaped, square, rectangular, hexagonal, elliptical, spindle shaped, and lenticular shaped aperture. 形態 細胞大致呈短圓筒形，一般高（貫殼軸）和寬（縱軸）近似或略小於寬。殼環面觀 大致呈矩形，殼面橢圓形，少數近圓形。殼面平，中部凸起或凹下。殼面縱軸兩端 各生一角毛。少數物種單獨生活，大部分物種相鄰細胞角毛交接相連形成或直或彎 或螺旋狀的長短不一的鏈。鏈端細胞的端角毛往往比鏈內細胞角毛粗、短。角毛的 形態、生長位置、伸出方向等是角毛藻鑒定的依據。不同物種細胞間隙也呈線條性， 啞鈴型，正方形，長方形，六角形，橢圓形，紡錘形，透鏡形等不同的形態。 Ecology and distribution
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