The eel is a carnivore, feeding only on other animals. It is an excellent predator. It is a nocturnal hunter, just to add a little bit to the “creepy factor.” If you’re afraid of snakes, good luck sleeping thinking of these eels crawling out of your local river and going on the prowl. Don’t worry too much about it, however, unless you’re a crustacean such as a shrimp, small fish, or aquatic insect. These are all common prey items of the Japanese eel.

The eel has a complete digestive system, starting with a mouth and culminating in an anus. After digestion, nutrients are taken up via a closed circulatory system, albeit a simple one. The blood is pumped in only one circuit. Deoxygenated blood is pumped from the heart to the gills, where oxygen is taken up. This oxygenated blood is passed throughout the body and returned to the heart. Excess food not needed for energy is stored on the organism as fat. Remember, this fat storage is absolutely critical to the eel’s ability to reproduce. Without fat storage, the eel will die well before reaching the ocean!

Although the eel is an excellent predator, it also makes for pretty good prey. Carnivorous birds (such as the Bald Eagle, although not for this species) are the greatest problem it faces, like many fish. Luckily, the eel’s elongated shape, along with the same developed musculature that allows them to travel on land, give them an extra defense most fish don’t have. When attacked by a bird of prey, the eel will fight back, attempting to strangle the bird much like a snake. Check out the series of pictures depicting this below!