Search This Blog

Tuesday, February 9, 2010

First Jellyfish

There are many different species of jellyfish in the world and they along with sponges, insects and vertebrates all belong to the group "Metazoa" and are all considered to have evolved from just one single ancestor, making them all related in one way or another however distant the relationship may be.

Although it is rather hard to pinpoint exactly when the first jellyfish was discovered it is known that Diploblasts, represented by jellyfish came about during the first of the major Metazoan radiation and are the first structurally primitive creatures that have a true nervous system. The polyorchis penicillatus jellyfish also known as the red-eye jellyfish, the bell medusa and also the bell-shaped jellyfish. These jellyfish have a bell or body which is at least equal in height as its width. They also possess around one hundred unbranched tentacles around the bell area all of which are evenly spaced out. When this jellyfish is swimming the tentacles may be contracted unlike when drifting in which instance the tentacles may be twice the length of the jellyfish's body. There are references of this jellyfish as far back as Eschscholtz, 1829.

There is much research available which dates back to the eighteenth century but the references made are generally to jellyfish as a whole rather than a particular species. Jellyfish have been around for hundreds of millions of years. It is possible in fact, that jellyfish were actually around before the dinosaurs roamed the earth, and there have even been suggestions of the possibility of the existence of "immortal" jellyfish. Fossils of jellyfish are rather rare to find purely because the jellyfish when fully grown are 95% water which means they do not actually leave behind any skeletal matter which in turn makes the chances of the jellyfish corpse creating a fossil quite slim.

It is thought that although they may have made a few changes throughout the millions of years they have existed for, jellyfish are still fairly much the same as they were back in the dinosaur ages, making only slight adaptations during evolution that were crucial to survival. One thing that is for certain is that the jellyfish species have found a way to survive on earth throughout the many changes the planet has gone through within the last 200 or more million years. From the ice age up until today with our increasing global temperatures, the jellyfish still survive and with the warmer global climates they even seem to be flourishing. Jellyfish are said to come from the same singular-cell ancestor as other sea creatures such as sea sponges and anemones which also have managed to survive the test of time.

There is no doubt that no matter how old jellyfish are, they are majestic and somewhat mystical sea dwelling creatures. In many old sea themed artworks from days when Vikings still sailed the seas, you can see many pictures which depict these gelatinous wonders all throughout the waters around the ship and there have even been primitive cave pictures found which appear to be depicting jellyfish.

No comments:

Post a Comment