Are giant jellyfish evolving to take over the seas?

With fish numbers all over the world falling thanks to overfishing and habitat destruction, a surprising predator has sprung up to take their place — the jellyfish. Due to their low energy requirements, the floating blobs of stingers don't need to be quite as active or accurate to spread and fill the ecological niche afforded them by changes in the ecosystem.

Even more curiously, the jellyfish appear to be adapting to be better hunters, too. An active predator fish has to spot prey and chase after it, but the Medusozoa just passively wait for their prey to come into contact with their poison stingers. So jellyfish are evolving into larger and even slower moving organisms, able to cover more area with their tendrils while still needing only small amounts of energy to survive.

Keep your eye on the beaches in the future. Sedate-seeming giant jellyfish may be the next megasharks.

Image:Moon jellyfish, Gijón Aquarium. Photograph by Julio Arrontes.
Courtesy of José Luis Acuña and Julio Arrontes, University of Ontario