For the last century humanity has directed its gaze to the sky, searching for alien life and worlds that defy logic and test the limits of imagination, yet such an alien world was right in front of us all along: the ocean. And as far as the ocean is concerned, there is not a predator as persevering as jellyfish.
Though the term “jellyfish” is pretty self-explanatory, their other name, medusa, comes from a Greek myth about a monstrous woman with wings, hideous face and snakes for hair that were constantly in motion.
Medusa was a protector of a treasure island, turning its victims into stone. The motion of jellyfish’s tentacles seemed similar to the way snakes moved in the legend, hence the name.
Jellyfishes are mostly made out of water, which is considered to take up to 95% of their bodies, and protein.
Though predators themselves, jellyfishes are also a prey to larger species, which made them adapt their appearance accordingly. Different types of jellyfishes can look drastically different: their size can vary from a few millimeters to up to ten meters, they can be completely seen through or shine brightly and the number of tentacles goes anything from zero to a thousand. They all share their signature half-sphere like body, which gives them their alien look.
Even though we are used to treating jellyfishes as a minor annoyance, the stings from some species are actually deadly – you won’t want to end up in the same neighborhood with this predator.
Jellyfishes can be found virtually everywhere: though they mostly live in salt water, some species can be found in fresh water as well.
An average lifespan of a jellyfish is one year, but there are cases of the ones that lived up to three years.
Theoretically jellyfishes are immortal though: they can only really die from external influences, if left alone they will descend to the bottom of the ocean, turning back into polyps and then repeat their life circle, which gives off even more of an alien vibe. But of course they are eaten by the fish long before that happens. Jellyfish and polyps, which can be found on the coral reefs and on the bottom of the ocean, are part of a life cycle of the same species: adult jellyfish lays eggs from which the polyps are born, who in turn bud and become full-fledged jellyfish. At each and every stage though jellyfish remains a full-fledged predator – they eat anything from zooplankton to small fishes.
As if it wasn’t already noticeable, jellyfishes have a really bizarre biology from a human point of view: they have twenty four eyes in their dome of a body, their mouth is actually used to both eating the food and discharging the waste, there are actually male and female jellyfishes, though they are similar in appearance their reproductive organs are shared between sexes and they don’t have a brain, though there is a type of nervous system that controls all of their behavior and impulses.
Some species show pretty advanced behavior: for example, Atolla jellyfish will flash the lights that are part of its body, distracting the predator and giving a jellyfish a chance to escape. In some cultures, mostly Asian, it’s customary to eat jellyfish – they are considered a delicacy and are told to have medical properties.
While they are part of a larger ecosystem, some jellyfish species are known to disrupt local ones – for example white-spotted jellyfish can practically eradicate the whole population of zooplankton in an area that they migrate to, leaving other species with nothing to feed on doomed to starvation.
Even though jellyfish look like they drift aimlessly through the waters and are even classified as plankton by scientists, some of the species actively peruse their prey, showing a behavior of true predators and using their deadly arsenal to a full capacity.
Jellyfish actually breathe through their skin – they evolved into a state of allowing them to use diffusion as a means of oxygenating their body.
You can actually buy one! Though it’s hard to look after such a pet as this there are benefits to keeping such an alien predator in your place – observing jellyfishes can serve as a source of meditation and relaxation, similar to looking at water and fire, and there are experiments condoned in order to determine how this wonderful creatures truly influence us. So if you want to both have a cute little alien predator at your disposal as well as help science now is your chance.