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
Jellyfish protein. Illuminating the animal or cell reveals what tissues express that protein—or at what stage of development. The fluorescence shows where the gene is expressed. Jellyfish are displayed in many public aquariums. Often the tank's background is blue and the animals are illuminated by side light, increasing the contrast between the animal and the background. In natural conditions, many jellies are so transparent that they are nearly invisible. Jellyfish are not adapted to closed spaces. They depend on currents to transport them from place to place. Professional exhibits as in the Monterey Bay Aquarium feature precise water flows, typically in