國立自然科學博物館

海膽的頂系肩負著海膽生殖、排遺與運動等重要的生理功能。正型海膽的頂系，如同一朵美麗的五瓣花，隨著種類不同，具有各種不同的顏色與形狀。其中，環刺棘海膽的肛門更形成「肛乳突」的圓球形構造，在海中吸引水中攝影者的目光。而歪型海膽類大脆心形海膽的肛門，則離開體殼頂部的頂系，在身體側後方形成造型奇特的開口。

The apical system regulates major physiological functions, such as reproduction, excretion of waste and movement, of a sea urchin. On shells of regular sea urchins, the apical system appears as a beautiful five-petal flower-like structure, as shown in Image 1. Among different urchin species, there are differences in the shapes and colors of the apical system. Moreover, the banded sea urchin Echinothrix calamaris possesses a globular anal papilla above the apical system, which easily attracts the attention of underwater photographers. In the irregular sea urchin Linopneustes, the anus is not part of the apical system, but is instead located toward the posterior, forming an oddly shaped orifice.

李坤瑄-海膽的菊花：頂系1

李坤瑄-海膽的菊花：頂系2

李坤瑄-海膽的菊花：頂系3