The jellyfish is a marine animal that does not stop to fascinate. This weird looking creature has inhabited the waters of the oceans of the world for thousands of years. Everything about them is different from the other creatures we encounter in the ocean. For instance their bodies are very delicate and made up of 95% water. The bell shaped body is filled with a gelatinous substance, and the jellyfish does not have a brain or any solid skeletal structure. It is the pressure of the water that keeps them alive and if you take it out of the water it will just collapse. 

There are 200 types of jellyfish in the world and they can live in the ocean at varying depths. Their bell shaped bodies, come in various sizes, ranging from a couple of centimeters in diameter to more than 2 meters. The can reproduce sexually, as well as asexually. Many jellyfish use a combination of both the types of reproduction and can multiply very quickly. 

Jellyfish are distinguishable as male and female. The male jellyfish releases its sperm into the water and the female releases the eggs. The adult jellyfish is capable of releasing the sperm and eggs in huge quantities. For example the sea nettle jellyfish, living in the Chesapeake Bay can release 40,000 eggs daily. The sperm will fertilise the eggs in the water, and they will form into larvae. These larvae then will float around and will be called planulae. They are oval shaped and have minute hair on the sides of their tiny bodies, which enables them to move in the water. 

The Planulae will float in the water for sometime and then start sinking to the bottom. They will seek a hard surface and attach themselves on it. The surface may be a rock or any other artificial surface like a rig or hull of a ship. The planulae now will develop into a stationery polyp. 

The polyp stage is quite interesting. The polyp looks more like a sea anemone at this stage. It has a long cup shape body with the mouth at the top. The mouth has tiny hair which capture microscopic plankton on which it feeds. The polyp starts growing in length, and then starts to bud. Budding is a process where the polyp starts to develop more polyps from its trunk. The new emerging polyp is identical to the first and is joined by a small feeding tube. This budding process is the asexual reproduction. The budding will multiply the number of polyps into a huge colony. This entire colony also will be stationery and the stage is considered sessile. 

Another interesting feature of the polyp stage is that, the polyp can opportunistically gauge the conditions of the environment, to see whether it is favourable for survival of the baby jellyfish. If is it senses unfavourable conditions it is known to extend the polyp phase for days, years or even decades. Once the temperature and food conditions become favourable it will start to release the baby jellyfish. A colony of polyps will generate thousands of baby jellyfish at a time. 

The baby jellyfish will then rapidly grow into an adult medusa, and the cycle will repeat itself. 
Normen FAdel
Author of the article
writer and blogger, founder of jellyfish .

New of label : Jellyfish Life Cycle and Reproduction

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