JellyFish Facts

Jellyfish Life Cycle

Jellyfish Life Cycle picture

Jellyfish Life Cycle

The jellyfish is one of the more easily recognizable marine creatures. We all know and remember the gelatinous bell shape of the body and long, swaying tentacles. However, it is interesting to know that the life cycle of a jellyfish which is very complex, actually involves the jellyfish passing through two different body forms, which are completely different from each other. Incredibly, the process of reproduction is both sexual and asexual at different times.

Here is a brief description of the entire life cycle of a jellyfish:

Fertilization: Like many other organisms, jellyfish are either male and produce sperm or female and produce eggs. When a male jellyfish is ready to mate, it releases sperm in the water through its mouth. When a female jellyfish passes by, these sperms get attached to her eggs. In her mouth, the process of fertilization occurs. Once the eggs are fertilized, they are either stored on the mother's mouth or in brood pouches along her oral arms. In different species of jellyfish, this process may vary and you may find that the eggs are fertilized in the mother's stomach. In some cases, the unfertilized eggs may be stored in the female's oral arms where they get fertilized by sperm in the water.

Planula Larva: After the embryonic stage, the larvae hatch and get transformed into free-swimming planulae. They then leave the security of their mother's body and set out on their own. A plunula has a small oval shape and has tiny hair on its surface that it beats together for movement. But, just like the adult jellyfish, most of its movements are entirely dependent on water tides and currents. Each planula floats around for a few days near the surface of the water and then sinks towards the ocean bottom.

Polyp (scyphistoma): After a planula sinks to the bottom, it attaches itself to a hard stationary surface. This cylindrical planula is attached to the surface at its base; at its top is its mouth surrounded by a few tentacles which gather food. As this polyp grows, it begins to form new polyps from its trunk, forming a polyp hydroid colony. All the polyp members of this colony are attached to each other by tiny feeding tubes. This entire stage in the life cycle of a jellyfish is a sessile stage, because the polyp colony is stationary and attached to a single surface. These colonies are known to grow to very large sizes and can exist for a number of years. Only after the polyp colony has grown to an appropriate size, will the next stage of the life cycle of a jellyfish begin.

Ephyra and Medusa: When the last stage is reached, the stalk of ployp begins to develop horizontal grooves. The topmost groove will free itself from the stalk as a baby jellyfish, known as ephyra. This ephyra will grow in size and become the adult jellyfish we all recognize. This last stage is the asexual reproduction aspect of the jellyfish's life cycle.

Learn more about Jellyfish, different Jellyfish Species, general Jellyfish Information, Jellyfish Pets and Jellyfish Safety




Written by and Sudarsana Sinha.

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