Here are some discoveries from a recent study of eels:
They migrate, leaving European rivers and shores on dark autumn nights.
At night, they swim up near the relatively warm surface of the sea, and then dive deep - several hundred meters - into very cold waters early each morning. The scientists speculate the cold delays reproductive development which would be inconvenient during the journey.
'Dr Kim Aarestrup, who is a Senior scientist at the Technical University of Denmark, National Institute of Aquatic Resources (DTU Aqua), and leader of the tagging work in the EU EELIAD project says: "This is a brilliant result in many different ways. Eels are difficult to follow once they leave European shores, so their behaviour as they migrate to their spawning grounds is almost a complete mystery."'
They learned the eels take an indirect route to the Sargasso Sea that takes advantage of ocean currents that improve their speed and arrival time.
[Technical University of Denmark (DTU) (2009, September 29). Unlocking The Mystery Of European Eel Migrations. ScienceDaily. Retrieved September 29, 2009, from http://www.sciencedaily.com /releases/2009/09/090929100652.htm]
From another article I learned the cusk eel and many species of fish make noises to attract mates and during competetive or antagonistic situations. Also read that fishes that live in the dark have more sensitive hearing than other fish.
1 comment:
Another hypothesis - my own - about why the eels swim deep below the surface during the day is that maybe they are designed for the dark. Maybe their eyes work better in low light conditions, and are easily damaged by sunlight.
There are many species of eel. True eels are actually fish.
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