Micro Life Zone
Asked by cocacolarulez to Arti, Chris, Dustin, James, Steven on 18 May 2012. This question was also asked by princess3498.
Keywords: bones, jellyfish
While bones give great support to animals that live on land, when in the water, the weight of an animal is decreased due to the buoyancy the water provides.
This decreased weight allows the animal to maintain structure much easier. An octopus for example doesn’t have any bones but maintains its shape. But if you take a jellyfish out of the water, you will see it doesn’t really hold its shape – though I wouldn’t recommend doing this as you may get stung.
Just like dustin said Jellyfish need no bones because the water helps to support its structure. In fact most jellyfish are about 95% water themselves! Despite having no bones they are still pretty complex though. They are composed of three layers: an outer layer, called the epidermis which is the fancy science word for skin; a middle layer made of a thick, elastic, jelly-like substance called mesoglea which is where most of the structure is determined; and an inner layer which acts like its stomach, called the gastrodermis. The shape of a jelly fish is kind of like a waterballon underwater, water in the middle and water on the outside and a thin layer (or in this case 3 layers) of stuff in between.
Hey cocacolarulez. The boys are absolutely correct. As an aside, think of the blue whale, the world’s largest mammal. It does have a skeleton and keeps its structure in the water perfectly. If you took it out of the water, it wouldn’t be able to hold its shape as the weight of the whale is too much. The density, buoyancy, and physical properties can really help many organisms keep their shape.
Great question! The boys have all explained this very well – the buoyancy provided by water is what keeps the jellyfish’s shape, as well as the shape of larger animals that would not be able to move well on land. This is how come whales get beached – they get stuck on the beach and can’t get back in the water because they can’t move well on land without the buoyancy provided by the water!
By BRIDGE8 under license from Mangorolla CIC 2023