There exist a lot of animals on planet earth with interesting facts surrounding their existence and it really shouldn't surprise you that the majority of these animals are basically found underwater, looking at the fact that just a little bit of the sea has been explored, and a vast remains in explored. Today we would be looking at one of this weird underwater animal - The JellyFish.
Contrary to what of people believe or as the name name suggests, a jellyfish isn't actually a fish. The jelly fish actually falls within the ambit of the plankton family and some distant relatives of sea anemones and corals. Quite notably, bodies of jellyfishes are essentially composed of just water, having no bones whatsoever. Result of recent research has shown that jellyfish are composed of about 95% water! The best way of of comfirming the result is through visualization, that is: when a jellyfish is washed up on the beach, after a period of time, due to evaporation, it would just disappear!
A very vital feature of the jellyfish is it's tentacles, although not all species have them, this tentacles serve a dual purpose as they are basically used for self-defense and catching preys.
Each of the tentacles are covered with a special set of cells called the cnidoblasts; these cnidoblasts are well capable of causing an extremely painful sting, although do not really have an adverse effect on humans.
The most intriguing aspect of jellyfish perhaps is the fact that, alongside not having any bones, eyes or gills (like fishes), jellyfish have neither brains nor hearts. That's definitely weird right? I thought so too. Keeping that in mind, one would want to ask, how do these animals even manage to stay alive, much more live quite a fully functional life
Well the answer to this isn't so far fetched, irrespective of the fact that jellyfishes do not have a brain or central nervous system, they have quite a basic set of nerves positioned at the base of their tentacles. These nerves are responsible for detecting temperature, salinity, touch etc. thus the jellyfish is able to reflexively respond to these particular stimuli. Jellyfishes do not have brains so they just live their passively, depending solely on their automatic reflexes.
Jellyfishes are able to sense light and thusget themselves oriented, by sensing it through light-sensitive cells which are positioned along the ridge of their bells. It's quite the same, making use of their different sense cells, they can sense chemicals which are in water in maintaining their balance. Since they don’t have a brain, The movements of jellyfishes are also limited, and are mainly dependent on the drifting of ocean waves, which they use to navigate about their habitats. For jellyfishes, catching their preys are really just a matter of chance, as they don’t passively hunt down their food; rather they just sit and wait for their preys to hit their tentacles. So now we know how jellyfishes manages to live without brains, but how do they live without a heart?! let's find out.
The heart is basically responsible for pumping blood around the body to enable the cells of an animal to derive appropriate nutrients and oxygen from the blood and also to expel soluble wastes products such as carbon dioxide. One special thing about the anatomy of the jellyfish is the outer layer, which is referred to as the Ectoderm; it's just a few cells thick, so oxygen can simply diffuses through to the the body of the jellyfish.
A jelly fish also has a very rudimentary digestive system, by which simple nutrients diffuse into the rest of the body. These two processes of nutrient diffusion and oxygen do not require an extremely powerful pump such as the heart for them to diffuse throughout the body of the organism, this is because of the simplicity of jellyfish anatomy.
Jellyfish are quite fascinating water animals which are able to survive even without a good number of the organs which we consider very vital for life. The body of the jellyfish is very much suited to live and survive the conditions which accompanies the endless blue oceans.