After migrating through thousands of miles all the way from freshwater rivers and streams, freshwater eels released their eggs within the Sargasso sea. According to Outfario, specialists think that this took place through external fertilization.
Nevertheless, eels' reproduction has been a mystery for quite some time. Specialists were left baffled by where and how the reproduction of these creatures took place. According to TED, the study of heels can be traced all the way back to ancient Greece. Up until this point in time, the species is still an object of study.
Freshwater eels can be spotted across the rivers of Japan, Europe, and other areas. However, nobody has ever witnessed their mating. Outdoria also notes how researchers were not able to spot any eggs or reproductive organs within dissections. How, then, do these creatures reproduce and multiply?
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External Fertilization
According to Facts, rather than mating with their sexual organs, the females release their eggs. The male's sperm, on the other hand, is also released into the water and then it comes into contact and fertilizes the egg.
Other fish species reproduce this way as well. The clownfish and salmon, for instance, also reproduce through external fertilization wherein the eggs get fertilized within the water.
From Saltwater to Freshwater
However, there is actually more to the species. Outforia notes that freshwater eels stand out among other marine life because certain periods of their life also get spent in saltwater. Though most of their lifespan is spent within fresh oceanic depths, these creatures get born in saltwater. They also die in these waters.
This is something quite unique to the species because several other fish cannot migrate from salt to freshwater because of their cells. Eels, however, are capable of handling such a drastic shift.
In order to adjust with the scarcity of salt, the kidneys of the species alter in order to carry higher levels of salt. When this happens, blood salinity levels get maintained.
When they reach a stage of maturity, the freshwater eels can be spotted within lakes and streams.
Freshwater Eel Breeding Site: Sargasso Sea
When the mating time arrives, these eels swim downwards as a group, moving deeper into the ocean or more specifically, the Sargasso Sea. This specific oceanic area, that has a span of up to two million square miles, is the breeding site for freshwater eels.
It can specifically be spotted in the West Indies, Bermuda, and Azores. Even if several eels are from faraway places, they do not hesitate to swim their way there.
Once the females spawn their eggs, these eggs will then float way up into the surface and hatch there.
Spawning: Eel's Last Life Event
When this spawning takes place, it is the last thing that an eel does. These creatures are incapable of living through this process. Hundreds of different eels meet together to release eggs. They, then, die altogether.
Upon arrival of the eels, females spawn eggs within the column of water. The males then expel their sperm. This, then, creates an egg that is fertilized.
RELATED ARTICLE: 'Epic' Eel Migration: Researchers Track the Creatures in Their Final Journey from European Rivers to the North Atlantic
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