How to elongate and divide?

Various sizes of Synura(flagellate colonies) visit the big particle to forage for food. To share the food equally, the colony needs to rotate periodically so that each individual member can access the particle surface. Meanwhile, the number of cells in one of the colonies increases and the whole colony becomes larger, probably because the individual members have multiplied. However, becoming too large may be inconvenient, so here we can see the division of one big colony into two smaller ones.

Commentary by Prof. Yuji Tsukii, Hosei University
As Synura belongs to Chrysophyceae, its growth depends on photosynthesis.

http://protist.i.hosei.ac.jp/PDB/Im.....

Actually I have never observed Synura eating bacteria. Furthermore, in this video we cannot see a structure like a food vacuole in each cell of the Synura colony, nor can we observe the process of cell division or colony separation.

Therefore the title of this video referring to repeated division is not accurate.

Sampling Date : 09 August 2009

Sampling Site : Hirose River B  Google Map