Their theca is divided into epicone and hypocone by the middle region (also called girdle or cingulum).

The flagellates have two different directions, one is surrounding the middle region while the other are in the longitudinal groove of hypocone.

The chloroplast in Peridinium is triple membrane, and some plastid-derived organelles like pyrenoid or eyespot also.

Most time of Peridinium are haploid vegetative cells and undergoing asexual or sexual cycle.

[13] The blooming event occurs because the organic mineral is flushed into the sea every year in spring.

Thus, the planozygotes of Peridinium break dormancy and release thousands of vegetative cells into the sea by feeding on diatom.

The break of blooming is related to high temperature, other phytoplanktonic competitor (Chytrid or Microcystis),[14][15] and human activities in the aquatic system by managing the water flow of the river.