Glass or Masked, Gobies We Hardly See You

THESE LITTLE GUYS ARE SO SMALL AND TRANSLUCENT THAT YOU HARDLY NOTICE THEM, but they’re actually pretty common on reefs in the Caribbean. Tiny fishes that swim in swarms of a dozen or so just off the corals, they’re either glass gobies or masked gobies. Both an inch or so in length, the two species are so similar that one source suggests the only way to be sure is to hold them in your hand

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Snakes on the Reef! They Won’t Bother You. Probably.

IF THE IDEA OF MEETING UP WITH SEA SNAKES ON A DIVE UNSETTLES YOU, here are two important facts about sea snakes and sea kraits: 1) They’re armed with highly deadly venom, and 2) They’re remarkably unaggressive. That being said, here’s another important thing about these two groups of sea snakes: Don’t mess with them. All sea snakes are venomous snake-like reptiles, but in anatomy and lifestyle, there are two different kinds. So, what’s the

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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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Porcelain Crabs Drop a Little Leg When Necessary

IF IT LOOKS LIKE A CRAB AND IT WALKS LIKE A CRAB, THEN IT MIGHT BE A PORCELAIN CRAB, which is a different thing entirely. Which leaves the question: What’s the difference between true crabs and porcelain crabs? They’re both decapods – crustaceans that resemble each other with hard outer shells and 10 appendages, including walking legs extending on their sides and large claws out in front. They both walk sideways, or “crab-like.” But the

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Horseshoe Crabs: Weird, Wonderful & Amazing

WEIRD AND WONDERFUL CREATURES, HORSESHOE CRABS are survivors from life’s earliest times who almost certainly have saved your life. And, they’re almost spiders. For the record, they’re not crabs in any way. If all that sounds overblown, consider the following horseshoe crab facts: 1)   THEY’RE WEIRD & WONDERFUL Beneath their dome-like carapaces, horseshoe crabs walk around the seafloor on 10 legs and they view the world with 10 eyes spread around their bodies, some 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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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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