Reader Question – Laura, Maringá, PR
In fact, they don’t sleep. At least not like us. For fish, there is no long period of rest dedicated to sleep. Instead, they slow down for a few seconds several times throughout the day. This happens because sleeping is a phenomenon linked to the level of metabolism of the animal. We humans have high metabolism and much greater energy wear. Therefore, a long and deep rest is essential for us, but not for them. Furthermore, for fish, sleeping could mean death, as they are always surrounded by predators.
With wide open eyes
Not all fish rest the same way.
SLEEPING WITH THE ENEMY
The clownfish resorts to protecting enemies when it’s time to relax. This is because the mucus produced by it does not chemically react with the poisonous tentacles of anemones. Thus, he goes unnoticed and protects himself among these predators in moments of less activity.
PROTECTED REST
The parrotfish secretes, at dusk, a layer of mucus so thick that it makes it unappetizing to predators. Thus, he spends the night more protected and can decrease activity for longer periods of time.
SWIMMING IS A MUST
Some species of tuna and shark cannot stop swimming. Never! Otherwise, they would drown. For them, swimming is not just a way of getting around, but also part of the natural breathing movement, causing water to circulate through their gills.
Consultancy: Francisco Manoel de S. Braga, doctor in fisheries biology from USP, and Roberto Goitein, doctor in biological oceanography from USP (both are professors in the Department of Zoology at Unesp)
Source: New school
See too:
+ 5 animals that will make you want to cry… they are so ugly
+ How do fish swim in schools without bumping into each other?