Little is known about the life cycle of many jellyfish, as the places on the sea floor where the benthic forms of those species live have not been found. According to some studies, the particular species of jellyfish Turritopsis nutricula is potentially immortal because, over time, it is able to rejuvenate more and more until starting a new life cycle.
This rejuvenation process, called transdifferentiation, appears to be caused by strong environmental factors that participate in the cellular changes of the organism. The largest jellyfish are found in the Scyphozoa class, the so-called scifomedusae, among which the Cyanea capillata stands out, widespread in temperate and arctic climates, which can reach 2.5 m in diameter.
The polypoid stage is very often reduced and in Stygiomedusa gigantea and Pelagia noctiluca, holoplanktonic species, it is instead absent.
Utility of jellyfish as marine biomonitors
On the Marine pollution bulletin, the researchers published an interesting study entitled: The utility of jellyfish as marine biomonitors.
The researchers analyse: "Jellyfish are abundant in coastal waters across broad latitudinal ranges and are often considered pests and a group that can cause phase shifts in marine ecosystems. Recent studies have highlighted their potential as biomonitors of contaminants including metals, herbicides and nutrients.
Traditionally , sedentary organisms like molluscs and annelid worms have been used, but some jellyfish have similar characteristics of localized distributions and in some cases sedentary behaviour.Broad gradients in contaminant accumulation have been shown for a number of planktonic jellyfish species.
An alternative biomonitoring candidate is the tropical/sub-tropical upside-down jellyfish. In laboratory and field deployments, Cassiopea accumulate measurable contaminants over days to weeks, making them ideal for detecting short-term pulses.Furthermore, the decay curve of contaminants varies temporally post -exposure and contaminant type.
This can provide an e estimate of the timing of exposure. Cassiopea, along with other jellyfish, have the potential to be an interesting and valuable group of organisms for monitoring coastal impacts."