Newly Discovered Microbe Transforms into Larger Cannibalistic Form

A single-celled protist discovered in aquarium filter material can increase to more than twice its normal size and consume smaller cells of the same species. The change occurs in stages. A cell first develops a larger mouth and moves rapidly before it can successfully capture and consume another cell. Once feeding begins, the cell body enlarges further into a supergiant form.

Supergiant cells move differently than normal cells.

They walk in circles and lose the swimming ability of smaller cells. The supergiants can return to normal size through asymmetric cell division. Each supergiant cell can produce up to nine normal-size offspring in 24 hours and as many as 16 within 120 hours. Normal-size cells divide once per day.

Researchers found that up to 42 percent of the organism's genes participate in the size transitions. The transformation tends to occur when food is abundant. The discovery may provide information on how simple organisms develop complex behaviors and how multicellular life evolved.