WEBVTT - Do Fish Sleep?

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<v Speaker 1>Welcome to brain Stuff, a production of iHeart Radio, Hey

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<v Speaker 1>brain Stuff Lauren Bogle bomb here goldfish of the animals,

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<v Speaker 1>not the crackers, are beautiful and inexpensive pets, and they're

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<v Speaker 1>known for being pretty hardy, which is why many of

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<v Speaker 1>us received one as an early pet, perhaps with less

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<v Speaker 1>preparation and equipment than is actually required, which is why

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<v Speaker 1>blacking an appropriate tank with a filter and water pump.

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<v Speaker 1>Many of us checked in on our fish a few

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<v Speaker 1>days later to find it floating upside down, motionless. In

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<v Speaker 1>our youthful innocence and curiosity, we might have wondered, is

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<v Speaker 1>that how fish sleep? It's hard to tell when a

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<v Speaker 1>fish is sleeping because they don't have eyelids, at least

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<v Speaker 1>not ones that close completely over their eyes, obscuring their

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<v Speaker 1>vision like ours do. But scientists know that fish do rest,

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<v Speaker 1>and some have very interesting ways of doing it. A

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<v Speaker 1>fish don't sleep the same way that you, or your dog,

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<v Speaker 1>or any other mammal does. Most don't seem to experience

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<v Speaker 1>cycles of rapid eye movement or r e M, though,

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<v Speaker 1>to be fair, we might just not know how to

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<v Speaker 1>recognize dream stayed activity in these animals. For example, research

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<v Speaker 1>on zebra fish suggests that they experienced similar brain activity

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<v Speaker 1>to R. E. M sleep, and other researchers have observed

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<v Speaker 1>an octopus changing colors while sleeping, which may suggest that

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<v Speaker 1>it was dreaming. Still, scientists have observed that many species

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<v Speaker 1>of fish rest. This is a period of restoration when

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<v Speaker 1>their metabolic functions slow and they're less active. A sufish,

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<v Speaker 1>like reef sharks, lay still at the bottom of the

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<v Speaker 1>ocean or inside caves when they sleep. These sharks have

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<v Speaker 1>a unique anatomical feature called a spiricle that forces water

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<v Speaker 1>out of the sharks skills so that they can continue

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<v Speaker 1>to breathe while they're resting, they're not as responsive to

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<v Speaker 1>their surroundings, but some species of sharks and tuna must

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<v Speaker 1>keep swimming to breathe because they don't have spircles to

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<v Speaker 1>keep water flowing over their gills. In their cases, scientists

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<v Speaker 1>hypothesized that they shut off half of their brains, which

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<v Speaker 1>is what dolphins do. They slow their breathing and move

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<v Speaker 1>more slowly, but are still somewhat responsive to their environment.

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<v Speaker 1>But some fish species, like the Spanish hog fish, are

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<v Speaker 1>known to sleep very soundly, so soundly in fact, that

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<v Speaker 1>divers can touch them and even move them to the

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<v Speaker 1>surface without disturbing their slumber. Some relatively deep sleepers create

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<v Speaker 1>their own protection. A parent fish, for instance, create enough

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<v Speaker 1>mucus to form a cocoon around themselves at night when

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<v Speaker 1>they stop moving. This mucus blanket is likely used to

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<v Speaker 1>keep blood sucking parasites from clinging to them while they sleep,

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<v Speaker 1>and clownfish bury themselves in sea enemies to protect themselves

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<v Speaker 1>from predators while they sleep. Like humans, fish have biological

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<v Speaker 1>clocks that tell them when to be alert and awake

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<v Speaker 1>and when to rest, and some sleep during the day

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<v Speaker 1>and some sleep at night. These tendencies primarily evolved based

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<v Speaker 1>on when they're more or less likely to be attacked

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<v Speaker 1>by predators or what the best times are to find

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<v Speaker 1>a meal. One of the more bizarre sleeping habits of

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<v Speaker 1>the ocean is experienced by loaches, which float to the

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<v Speaker 1>top of the water and remain completely still when they

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<v Speaker 1>sleep for short periods. So if your pet fish is

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<v Speaker 1>a loach and it's motionless at the top of the tank,

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<v Speaker 1>it could very well be sleeping. Unfortunately, the same cannot

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<v Speaker 1>be said about that pet goldfish, which tend to rest

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<v Speaker 1>towards the bottom of their habitat, not upside down near

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<v Speaker 1>the surface. Today's episode is based on the article do

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<v Speaker 1>fish Sleep on how stuff works dot Com, written appropriately

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<v Speaker 1>by Allison Troutner. Brain Stuff is production of I Heart

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<v Speaker 1>Radio in partnership with how stuff works dot com, and

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<v Speaker 1>it's produced by Tyler Klang. For more podcasts my heart Radio,

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<v Speaker 1>visit the heart Radio app, Apple Podcasts, or wherever you

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<v Speaker 1>listen to your favorite shows. M