The Immortal Jellyfish

The immortal jellyfish is also relatively inconspicuous, which may have contributed to its spread being difficult to spot. It is tiny and translucent, and can have different features depending on where in the world it's living. From a study of T. dohrnii around the world, researchers found that immortal jellyfish in tropical regions like Panama had only eight tentacles, whereas those in more temperate waters, such as in the Mediterranean and Japan, can have 24 or more. It is not clear yet why they differ.