American eels can reach five feet in length during the fourth stage, which lasts up to 40 years. In this phase, they are nocturnal bottom predators that rely on their keen sense of smell.
“American eels are opportunistic hunters,” explained Reuben Goforth, lecturer in aquatic ecosystems. “Their flexibility gives them plenty of options when looking for their prey. They mainly eat invertebrates like aquatic insects and crayfish, but if they come across a small fish it will also be on the menu.
Towards the end of their lives, the eels’ bodies adapt one last time to prepare for their return to the Sargasso Sea. Their digestive tract degenerates and their fat stores increase. Their pectoral fins widen and their eyes double in size.
When they reach the sea, female eels lay millions of floating eggs and die.
While eels travel well, Goforth describes them as secret creatures.
“I suspect they are more common than we think because the opportunities to see them are so small. American eels like to hide. They are nocturnal and their elongated bodies allow them to easily enter complex habitats. such as tree roots, aquatic vegetation and rock crevices, they can even burrow in mud or sand.
Although it’s rare to encounter an eel in Indiana, Goforth thinks their characteristic adaptability could increase their numbers in the state. “American eels are threatened by hydroelectric dams. The Mississippi River basin (which includes the Wabash River) may become more important for American eels in the future because there is less handling. We might see changes as habitats are lost. It’s speculative, but it’s a possibility that will be very interesting to watch.