Wednesday

The Mysterious Life of Eels

Eels are one of the least understood groups of fish in the world. They are so cryptic that scientists classified their life stages as multiple species. Their life cycle spans oceans an rivers and can take years to complete. It all begins when fully grown freshwater eels lay their eggs in the ocean. These eggs hatch into what is known as a leptocephali (singular leptocephalus). These little creatures are almost totally transparent and have no red blood cells. They feed on marine snow and can grow up to 12 inches. These things make them unlike most other fish larvae. After a period of 3-12 months the leptocephali grow into glass eels, also known as elvers. At this point they swim toward estuaries and begin to gain coloration as well as the common eel body shape. Elvers are frequently caught and sold for food with the price for a pound reaching $2,000 this year. Because of this, they are becoming a heavily fished animal and their numbers are dropping. The elvers grow larger in the rivers and streams growing into yellow eels, the juvenile stage before sexual maturity is reached. The yellow eels mature into adults which go on to produce more eggs starting the whole process over again.
Another cool fact...
Some species, such as the Moray, have a second set of jaws, known as pharyngeal jaws, that come forward when the mouth is open. These jaws allow the eel to bring prey into its mouth as their jaw is too narrow to create the negative pressure to suck in prey (the common feeding method in fish).

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