Woodsy Perhaps, But Mangrove Forests are Essential Parts of the Reef

THREE THINGS TO KNOW ABOUT MANGROVE FORESTS: 1) They aren’t swamps. They grow in shallow ocean waters along tropical coasts, surviving tidal fluctuations and thriving on the edge between land and sea.  2) Mangrove trees generate the freshwater they need for survival by using a variety of mechanisms to filter the salt out of the ocean water.  3) They’re essential parts of reef systems, key to the reef life. ABOVE AND BELOW    Above water,

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Osteichthyes vs. Chondrichthyes, Bony vs. Cartilaginous

The terms Osteichthyes and Chondrichthyes may seem a trifle wonkish, as opposed to street talk like “bony fish,” “sharks” and “rays,” but you will encounter them from time to time and should at least be aware of them. •   Osteichthyes (os-tee-ik’-thee-eez, from the Greek for “bone” and “fish”) is the taxonomic class of bony fishes, those with hard, rigid skeletons based on calcium, phosphate and other minerals, smooth scales, covered gills and flexible fins. With

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Stony, Soft or Gorgonian, They’re All Coral Polyps

WHEN PEOPLE SEE THE WORD “CORAL,” it very likely brings to mind the great mounds of star and brain corals that stand out on the reefs. In fact, “corals” include many organisms beyond the familiar stony formations, all built on similar, tiny, coral polyps. “Coral” itself is a flexible word. It applies to the coral exoskeletons that we see as the visible shells of hard corals, to the polyp animals that live within those exoskeletons

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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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“Whale Falls” Have Large Impacts in the Deep Sea

WHEN A WHALE FALLS TO THE DEEP SEAFLOOR, A COMMUNITY FORMS AROUND ITS NUTRITIOUS CARCASS. Scavengers like sleeper sharks and hagfish arrive first to consume skin and muscle. Microbes convene to work on the scraps those fish scatter. Worms, snails and crabs show up to graze through its array of bones. Newly described worms called Osedax, which live only within the bones of fallen whales, appear. By one estimate, there may be hundreds of thousands

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 Fish Buoyancy – How Our Finny Friends Stay Neutral (Unless They Don’t)

ONE THING IS CLEAR – FISH HAVE BETTER BUOYANCY THAN YOU.  And, they don’t have to press any buttons. Many bony fishes have built-in versions of the buoyancy-compensators that divers use to control their position in the water versus changing ambient pressures. In these fishes’ case, it’s an internal gas-filled sac called a swim bladder that automatically works to counteract the ambient pressures applied by the waters surrounding it and keep the fish at neutral

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The Difference Between Jellyfish and Comb Jellies

WHAT’S THE DIFFERENCE BETWEEN JELLYFISH AND COMB JELLIES?  They both come in blobby shapes and gelatinous, transparent bodies. But comb jellies – ctenophores – are entirely different from their oceanic jellyfish neighbors. Most importantly: They don’t sting. And some of them put on fantastic light shows. Note that I said “neighbors,” not “cousins.” The difference between jellyfish and comb jellies runs far deeper than the absence of stinging.  Recent research suggests that combs evolved with

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How to Treat Stings: Jellyfish & Fire Coral

  LET’S TALK ABOUT HOW TO TREAT STINGS. My front page post, “Nematocysts and the Science of Sting,” discusses the way jellyfish, fire coral and other cnidarians bring about their painful stings. On dive boats, in dive shops and, of course, on the internet there are lots of theories about how to treat stings by cnidarians – most of it more urban legend than factual. Here are some facts, culled from medical resources. THINGS YOU SHOULDN’T

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 Nematocysts & the Science of Sting

NEMATOCYSTS ARE OCEAN STINGERS’ SECRET WEAPONS. In fact, they are the stingers. The way in which nematocysts sting is a story of the sneaky, harpoon-like ordnance of Phylum Cnidaria – jellyfish, coral and gorgonian polyps, sea anemones, fire corals and hydroids. If you happen to touch a sea anemone, a sea plume or coral tentacles (which you shouldn’t do), you’re likely to not feel their sting. Actually, you’ve probably been stung, ineffectively. Those animals’ stingers

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How Sharks Smell Blood – Superbly, But Not Miles Away

HOW SHARKS SMELL BLOOD IS FAR MORE INTERESTING than their mythical ability to detect the scent of “a drop of blood miles away.” Scientists disproved that legend long ago, although you may still find it in cheesy movies and on shark-week type reality shows. Sharks do have an amazing sense of smell, but their long-range detection capabilities are limited to several hundred yards rather than miles, many authoritative sources suggest. And one study suggests that

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