Jellyfish Jellyfish Jellyfish or sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are not mobile, being anchored to the seabed by stalks. The bell can pulsate to provide propulsion and highly efficient locomotion. The tentacles are armed with stinging cells and may be used to capture prey and defend against predators. Jellyfish have a complex life cycle; the medusa is normally the sexual phase, the planula larva can
Jellyfish Lake on Koror. The golden jellyfish population in Big Jellyfish Lake, Koror did not seem to be affected. The reason for this was not clear, but Big Jellyfish Lake experienced lower temperature increases than the other lakes and there was experimental evidence that the golden jellyfish medusa from Big Jellyfish Lake were more tolerant of higher temperatures. Although Clear Lake did not seem to have experienced the complete medusa population die-off that Jellyfish Lake did in 1998, the golden jellyfish medusae in Clear Lake are not always present. When conditions are not favorable for the short lived medusa stage or for