Nature News

Jellyfish Life Cycle

Did You Know…?

There is one species of jellyfish that is known to live forever? But before I tell you more about this extraordinary jellyfish, we first have to understand the life cycle of the jellyfish, since that cycle is nothing like our own.

You probably have seen a jellyfish sometime in your life in the waters around Bonaire. They come in a large variety of shapes and sizes: from harmless jellies that don’t sting to pretty harmful ones (luckily these species aren’t very abundant here). Although they all look different, most jellyfish undergo similar life stages.

A jellyfish is either a male or a female, and it reproduces sexually when it becomes an adult. After the eggs – held by the female jellyfish – are fertilized, they hatch, releasing tiny, swimming larvae. The larvae attach themselves to the sea floor and transform into plant-like structures called polyps. Each polyp grows and forms many segments which are identical to each other (clones). The topmost segment is released and swims off as an immature jellyfish. The ones below it follow soon after. So, jellyfish reproduce sexually (by mating) as well as asexually (by cloning).

Two weeks ago, thousands of Sea Thimble Jellyfish (Linuche unguiculata) were seen along the west coast of Bonaire. The Sea Thimble adult (medusa) is only a centimeter wide and the larvae are even smaller, less than 1 millimeter wide. Some people came out of the water with a skin rash. This rash, also called ‘sea bather’s eruption’, is caused by the larvae of the Sea Thimble, which fire off their tiny stinging cells when they get trapped under swimsuits (or underarms). The larvae will eventually settle on the bottom, grow into polyps and release young jellyfish. These will mature, reproduce and eventually die from predation, sickness, or old age. But, as you read in the beginning of this article, there is one species of jelly that may not die, but rather, has been observed doing something extraordinary.

The Immortal Jellyfish (Turritopsis dohrnii) adult has the ability to transform itself back into a polyp when it is exposed to environmental stress, sickness, or old age. It does this by settling back onto the bottom and converting its old cells into new, young cells and then does what polyps do – clones itself and therefore goes on living! As you may imagine, scientists are very interested in this species. Imagine us having the ability to transform ourselves into babies when we get old or sick. Who would have thought that the fountain of youth could be coming from a jellyfish?