planaria

Planaria Ripping Themselves Apart

Planaria are little flatworms with triangle heads, beady eyes, and the ability to regenerate after being cut in half. Bet you didn’t expect that last part, did you? Unlike cell division, planarian fission is violent and … well, weird. To stimulate these little guys to split, you have to first decapitate them. Unlike mitosis, planarian binary fission is simpler. There are no chromosomes that form or mitotic spindles. The worm simply holds on to a surface with its pharynx, uses peristalsis to create a waist, and pulsating muscular contractions rip the worm in half. The tighter the worm is able…