noctiluca is capable of producing light, but it has been suggested that it may function as a way to communicate. This jellyfish is very colourful and will phosphoresce when disturbed, leaving luminous mucous if handled. The estimated life expectancy of the mauve stinger is 2-6 months, with death usually caused by rough waters. Although in humans such contact is not lethal, it can result in considerable discomfort. The mauve stinger is capable of delivering a strong toxin-filled thread to any organism which may accidentally come into contact with it. It has distinct tissues, but no organs, and a single body opening. The mauve stinger has eight tentacles and four oral arms. It is pink to purple in colour and striped in appearance. It is a small jellyfish, with a bell ranging between 6-10 cm in diameter and a wavy-edged float. Trawling and other methods impacting the seabed could create improved conditions for jellyfish: removing competitors and predators from the seafloor while simultaneously leaving rocky outcrops as jellyfish refuges may give the advantage to jellyfish over fish. To make matters worse jellyfish prey upon the eggs and larvae of fish species, directly impacting on fish populations. However, turtles are one of only a few predators of larger jellyfish but are themselves at risk from overfishing and so negates any corrective effect they might have on jellyfish numbers. Large marine creatures such as turtles prey upon larger jellyfish, so an increase in jellyfish abundance may seem like good news for critically endangered species like the leatherback turtle. This shift in the ecosystem is then amplified as the sheer numbers of jellyfish outcompete the fish by preying on the same zooplankton species. The collapse of small fish living closer to the surface, such as sardines or anchovies, can reduce predation pressure on jellyfish while increasing jellyfish food sources. Systematically removing large predatory fish like tuna and cod, as well as overfishing crustaceans and molluscs, can lead to devastating changes. Gradually, large organisms, species diversity and structural diversity are replaced in ecosystems by more primitive species groups such as jellyfish.
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