how do fish sleep

How Fish Sleep: By Resting, Snoozing & Totally Zonking Out

HOW FISH SLEEP DEPENDS ON THE SPECIES. Nocturnal fishes, like cardinalfishes and those closely packed platoons of grunts and gray snappers you see just hanging around by coralheads and pier pilings during day dives, are likely resting rather than actually sleeping. Some species, like parrotfish, clearly sleep at night, although they seem like they can be awakened with minor disturbances (I base this on my own clumsiness around them on night dives). Some, like bluehead

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Wet & Great: Underwater Photographer of the Year, 2019

WINNERS FOR THE UNDERWATER PHOTOGRAPHER OF THE YEAR’S 2019 COMPETITION have been announced and as usual, the results are stunning. Drawing entries from around the world, the United- Kingdom-based group judges photos in eight categories – Wide-Angle, Macro, Portrait, Compact, Behavior, Black & White and Up and Coming – plus three British Waters categories, Wide Angle, Macro and Compact. Here are several samples from this year’s winners. SEE THEM ALL You can view the all

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Right Whale Calves, Deep-Diving Beaked Whales, Migrating by Memory

LINKS TO INTERESTING STUFF ON THE WEB – CETACEAN EDITION “Seven North Atlantic Right Whale Calves Spotted So Far This Year,” The Scientist    The number is still too low to be sustainable, but last year it was zero, so it’s promising. “Beaked Whales Are the Deepest Divers,” New York Times   Not that much is known about them, but they dive deeper and can stay longer than any other marine mammal.  “Migrating blue whales rely on

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Hunting Shark Teeth: After the Feeding Frenzy, the Shark Tooth Frenzy

SHARKS ARE KIND OF NOTORIOUS FOR HAVING TEETH – it is, after, all the principal reason we fear them. But they’re also famous for losing them. And some of us diving human beings are famous for hunting shark teeth. In fact, sharks drop teeth continuously. Inside their powerful jaws, they have multiple rows of choppers. When one falls out, one behind it moves forward to take its place, as if on a conveyor belt. Over

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Feather Duster Worms Speak with Quiet Grace

WHAT’S THE DIFFERENCE BETWEEN FEATHER DUSTER AND CHRISTMAS TREE WORMS? For one thing, the conical feathery crowns of Christmas tree worms shout out their presence with color and beguiling shapes. Feather dusters’ fan-shaped crowns often whisper with subtle elegance. If it’s simply about appreciating the beauty of the reef, that’s the main point – conical versus fan-shaped, bold versus muted. It’s the fan shape that gives feather dusters their other common name, fan worms.  

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A Great White Shark Swim, Octopus Farming, Faster Fish

INTERESTING STUFF FROM AROUND THE WEB A marine biologist snorkeled with a great white shark, even touching it. She called it “magic.” Others call it risky behavior and tell you to please not try it. Story and video, Washington Post. An anomaly in our age of global warming, a deep region of the Pacific Ocean is actually cooling. It’s because of the very slow churn of the Great Ocean Conveyor Belt; the water in question

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The Conch Republic Has Just Banned Coral-Toxic Sunscreens, and So Should You!

THE EVIDENCE IS CLEAR: THE MOST COMMON CHEMICALS FOUND IN SUNSCREENS, OXYBENZONE AND OCTINOXATE, are damaging to coral reefs and contribute to coral bleaching. The city of Key West in Florida has just joined the state of Hawaii in voting to ban the sale of coral-toxic sunscreens. At stake is the health of their fragile reefs and, obviously, their futures as destinations for millions of divers and other tourists. They’d like to see reef-safe sunscreen

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Some Sharks Have to Swim to Survive, But Most Don’t

DO SHARKS HAVE TO SWIM CONSTANTLY IN ORDER TO BREATHE? The answer is yes – for the relatively small number of shark species that excite us the most, like great whites and hammerheads. But it’s not the case with most of the 400-plus species of sharks in the oceans, like the familiar nurse shark and lesser-known species like bullhead, angel and carpet sharks. WATER, OXYGEN & GILLS Like all fish, sharks breathe by extracting oxygen

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Stomach-Everting, Arm-Regenerating Starfish Explained

BOTH LITTLE KIDS AND MARINE BIOLOGISTS KNOW STARFISH BY THEIR FIVE ARMS. The starfish anatomy that lurks underneath a starfish’s bumpy skin is another thing (To be clear, the biologists know sea star facts, the rest of us not so much). There are 1,500 to 2,000 species of starfish, or sea stars, found in oceans worldwide, in pretty much every depth and type of habitat. They’re all alike in general architecture but come in a myriad

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Watch How Starfish Walk…and Bounce

WITH FIVE ARMS STRETCHING IN FIVE DIRECTIONS, you’d think that starfish could move along the seafloor like Indiana Jones. In fact, usually they creep along on hundreds of little tube feet that line the undersides of those arms. But, researchers studying how starfish walk found something else: sometimes starfish bounce along for speed. As echinoderms in Class Asteroidea, starfish walk by operating their multitudes of little tiny feet through intricate networks of fluid-filled canals. With

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