The other day, I was teaching an Advanced Open Water course and we had the pleasure of encountering a massive jellyfish. We do see them on occasions here on Koh Tao, but they are relatively rare, so it’s always a treat. Especially when we see the big ones. It can be a little difficult to identify species of jellyfish, but I think it was a white-spotted jellyfish.
They’re such strange animals that it made me wonder more about them. Turns out they are not fish at all. They don’t have specific organs for respiration, digestion or circulation. In fact, they don’t even really have a central nervous system. They just have nerves spread throughout their bodies.
Jellyfish bodies consist of about 95% water and their skin is so thin that they don’t really breathe, they just get their oxygen by diffusion. They eat by stinging whatever they come across and jamming it into their bodies. Because they are transparent, sometimes we see small crabs in their “stomachs”.
Always a pleasure to come across one of these strange beings.