Jellyfish as food jellyfish, which may utilize salt curing to accomplish this, creating a dried finished product. Some commercially processed edible jellyfish are purveyed in dried sheets. The process of producing dehydrated jellyfish typically includes the removal of the tentacles prior to drying, because the upper dome area of the marine animal is the part typically used for cooking. Jellyfish deteriorate rapidly at room temperature so processing starts soon after they are caught. The bell is separated from the dangling oral arms and both are washed in seawater before being scraped to remove the gonads and mucus. Dehydration is traditionally undertaken by sprinkling
Jellyfish disperse widely and is followed by a sedentary polyp phase. Jellyfish are found all over the world, from surface waters to the deep sea. Scyphozoans (the "true jellyfish") are exclusively marine, but some hydrozoans with a similar appearance live in freshwater. Large, often colorful, jellyfish are common in coastal zones worldwide. The medusae of most species are fast growing, mature within a few months and die soon after breeding, but the polyp stage, attached to the seabed, may be much more long-lived. Jellyfish have been in existence for at least 500 million years, and possibly 700 million years or more,