Jellyfish diameter; the tentacles and mouth parts usually extend beyond this bell dimension. The smallest jellyfish are the peculiar creeping jellyfish in the genera "Staurocladia" and "Eleutheria", which have bell disks from to a few millimeters in diameter, with short tentacles that extend out beyond this, which these jellyfish use to move across the surface of seaweed or the bottoms of rocky pools. Many of these tiny creeping jellyfish cannot be seen in the field without a hand lens or microscope; they can reproduce asexually by fission (splitting in half). Other very small jellyfish, which have bells about one millimeter, are
Blue jellyfish a similar way to the life cycle of the moon jellyfish. Blue jellyfish Cyanea lamarckii, also known as the blue jellyfish or bluefire jellyfish, is a species of jellyfish in the family Cyaneidae. Populations in the western Pacific around Japan are sometimes distinguished as "Cyanea nozakii" or "Cyanea capillata nozakii". This species is found in the pelagic zone off the west coast of Scotland, the North Sea and the Irish Sea, sometimes with the more common Lion's Mane Jellyfish, ("Cyanea capillata"). "C. lamarckii" has a blue or yellow tone and grows to approximately 10 to 20 cm across, but specimens