Dr Craig R McClain
@drcraigmc
Deep-sea biologist. Two obsessions: the biodiversity of Earth's largest habitat, and why body size varies across all of life. Science communicator, ocean's weirdest animals daily.
And it is full of life. The cave runs its own food web with no sunlight at all, fueled by bat guano and debris washed in from above. Blind salamanders, eyeless isopods and amphipods, and other animals live their whole lives in the dark. Our guide put the count around 140 species.
And it is full of life. The cave runs its own food web with no sunlight at all, fueled by bat guano and debris washed in from above. Blind salamanders, eyeless isopods and amphipods, and other animals live their whole lives in the dark. Our guide put the count around 140 species.
Deep inside, the water and air hold a constant 58°F year-round, and an underground stream runs through total darkness, still carving the cave deeper. A world with no light and no seasons. Not so different from the deep sea I usually think about.
It’s what geologists call a living cave. The stalactites, columns, and flowstones are still slowly growing, fed by mineral-rich water dripping through that ancient limestone. Most show caves are geologically dead. This one is still being built, one drop at a time.
Went to Blanchard Springs Caverns in Arkansas yesterday. The whole cave is built from limestone, built from the shells and skeletons of sea creatures that lived here over 350 million years ago, when Arkansas sat under a shallow sea. Even in an Ozark cave, I cannot escape the ocean.
#Arkansas water, familiar to me for a long time. Reenergizing on the White River in Arkansas. Bull Shoals Dam pulls water from 120 feet down in the reservoir, so what comes out stays 48 to 54°F all year. That cold, deep water turned a warm bass river into 100 miles of world-class trout water.
The appropriately named piglet squid floats mostly upright in the deep, full of ammonia for buoyancy, with a little tuft of tentacles on top and a light organ under each eye. It looks less like a predator and more like something that lost a bet. #MolluscMonday #marinelife
Bonellia viridis is a spoon worm where the female is a fat green blob and the male is microscopic and lives inside her. Sex is decided by luck: larvae that land on a female become male, larvae that land on bare mud become female. Mud determines your sex. #WormWednesday #marinelife
Carinaria is a sea snail that swims upside down in the open ocean with a tiny shell perched on its back like a party hat several sizes too small. It's a mostly transparent predator in a party hat, and there is no party. There was never going to be a party. #MolluscMonday #marinelife
Xenoturbella is a deep-sea animal that is essentially a flat, sock-shaped blob with no brain, no gut ends, no eyes, and no discernible opinions. Scientists have spent years arguing about where it even belongs on the tree of life. It, meanwhile, is a sock. #marinelife
Happy early July 4th from the Christmas tree worm, which comes in red, white, and blue, among many other colors. It fans these feathery spirals out to breathe and feed, then yanks them into the coral the instant anything comes near. All the colors, none of the risk-taking. #marinelife
The largest arthropod that ever lived was a sea scorpion (Eurypterids). Jaekelopterus reached about 2.5 meters, longer than a person is tall, hunting the seas 400 million years ago before fish took over as top predators. #FossilFriday #marinelife
A decade of watching Arctic deep-sea life found the deepest communities, past 4,000 m, are the most fragile. They run on so little food that a single warm-water anomaly reshapes them. Depth and food set the rules down there, same as always. #marinelife www.sciencedirect.com/science/arti...
New Arctic work finds the edges of a methane seep are up to ten times more species-rich than the seep center. The rich zone gets the chemosynthetic food without the harsh chemistry of the seep itself. An ecotone doing what ecotones do. #marinelife link.springer.com/article/10.1...
Couldn't find a good photo for a sea mouse, but I got some photos from worms in our lab.
The sea mouse is not a mouse. It's a chunky marine worm covered in felt-like hair that diffracts light into shifting reds, blues, and golds, some of the best natural photonics we know of. A brown lump on the seafloor that turns into a rainbow when the light hits right. #WormWednesday #marinelife
A new survey of the Japan and Izu-Ogasawara trenches filmed a slow-gliding animal at 9,137 m that taxonomists still can’t place in any known phylum. It vaguely seems a sea slug or a sea cucumber. For now it’s logged simply as “animal, position uncertain.” #marinelife doi.org/10.3897/BDJ....
Spent today staring at 300+ deep-sea family lineages and how their body size shifts with depth. Some shrink. Some balloon. Most do... nothing dramatic. Turns out the chaos lives almost entirely at the family level, order and phylum barely matter. Science is messy and I love it. #science
I also like this one by I believe Sean McMahon at Yale University
Tullimonstrum gregarium. The Tully Monster. A 300-million-year-old animal from Illinois so strange that scientists still can't agree what it even is. Eyes on stalks like a hammerhead, a long claw-tipped proboscis where a mouth should be. Decades of debate, no consensus. #FossilFriday #marinelife
None of this happens without a great team. Lucky to be out here with grad students and postdocs who show up at 4am, haul the mud, and still keep the boat laughing. The future of marine science is in good hands.
Storms building on the horizon, but we’re keeping a close eye on it and staying safe out here. Fieldwork is half science, half weather app.
Ramisyllis multicaudata has one head and up to a thousand rear ends. It lives inside a sponge, and every time its body branches into a new channel, all the organs branch too. One worm, shaped like a tree, threaded through its host. #WormWednesday Image from onlinelibrary.wiley.com/doi/10.1002/...
The squidworm (Teuthidodrilus samae) isn't a squid. It's a swimming polychaete from ~3,000 m down in the Celebes Sea. The ten "tentacles" off its head are sensory appendages as long as its body, used to smell and feel through the dark. #WormWednesday #marinelife Images from doi.org/10.1098/rsbl...
At my parents’ grave this morning. My dad served in the Army; my mom taught in public schools for years. One protected the country, the other shaped it, classroom by classroom. They’re buried side by side, and I visited them both today. Love you, miss you.
This scale worm, Macellicephaloides grandicirra, lives almost entirely below 7,000 metres in deep ocean trenches and unlike most of its relatives at that depth, it never gave up the hunt to hide in a burrow. #marinelife