Meet Schmidt. Schmidtea mediterranea is a hermaphroditic, googly-eye-spotted flatworm that sometimes chooses to reproduce by breaking in half and regenerating two new bodies, but that's not the most interesting thing about her/him. This tiny animal has just demonstrated to biologists that a part of the cell crucial to all animal life on Earth is, in fact, optional.
You might remember the centrosome from high school biology as a pair of perpendicular, hot-dog-shaped objects inside a cell. Just before cell division, this structure duplicates itself, and the two centrosomes travel to opposite ends of the nucleus. Then each centrosome sends a cascade of delicate fibers toward the center of the nucleus, where the chromosomes have already copied themselves and paired off in an orderly manner. The fibers latch on to the chromosomes and drag them back to the poles of the nucleus, one copy on each side. After this, the cell ...
