At the surface, each of those cups was 90% air and 10% tiny polystyrene beads. After each cup is artistically adorned with deep-sea imagery, they take a plunge to the abyss. At the crushing pressures of the depths, the air is squeezed out, leaving only those tiny polystyrene beads, and each cup becomes a miniature of its former self. One of the most extreme environmental gradients is the increase of pressure with increasing depth, starting at 1 atmosphere at the surface and reaching well over 1,000 atmospheres in the deepest parts of the ocean. How do organisms survive this great pressure, and what happens to them when they are brought to the surface?

The highest known pressure in the deep oceans coincides with the maximum known depth at the southern end of the Mariana Trench, the Challenger Deep. The actual maximum depth of Challenger Deep is disputed. The deepest reported measurement was by a Russian research vessel at 11,034 meters. The International Hydrographic Organization adopted 10,924 meters in 1993, but a subsequent 2010 survey, the most accurate to date, places the depth at 10,984 meters—25 meters greater. With every 10 meters corresponding to 1 atmosphere of pressure, this places the maximum known pressures in the deep between 1092.4 and 1103.4 atmospheres (110.7–111.8 MPa). Notably, several other deep-sea trenches—Tonga, Philippines, Kuril-Kamchatka, and Kermadec—in the Pacific Ocean also reach depths greater than 10,000 meters. In the Atlantic Ocean, the two deepest trenches are the Puerto Rico Trench at 8,800 meters and the South Sandwich Trench at 8,428 meters.

Exploring the depths of the ocean reveals a fascinating array of life forms, showcasing the incredible adaptability of both prokaryotic and eukaryotic organisms to high-pressure environments. Even in the Challenger Deep, where pressures exceed 110 MPa, microbial life thrives. Interestingly, several large multicellular organisms have been discovered at these extreme depths. A striking 74% of species found below 7,000 meters are endemic to these very deep areas. Among these invertebrates are the sea cucumber Myriotrochus bruuni, which inhabits the Mariana Trench at 10,710 meters, and the amphipod Hirondellea gigas, one of the most abundant creatures in the Challenger Deep at 10,897 meters. The hadal snailfish Pseudoliparis swirei holds the record for the deepest known vertebrate, living at an astonishing 7,966 meters.

How do organisms survive this depth? In short, there is a host of remarkable physiological and biochemical strategies that allow organisms to survive and thrive under the immense pressures found in the ocean’s depths. These adaptations include unique cellular structures and molecular mechanisms that confer resilience to high-pressure environments, such as specialized cell membranes, pressure-resistant enzymes, and unique protein folding techniques.

As you may remember from high school or college biology, a cellular membrane consists of a lipid bilayer. The structure is maintained entirely by the interaction of charges (or lack thereof) between water and the phospholipids. This makes the membrane semipermeable, much like a layer of oil on water. Extreme pressure results in tighter packing of the phospholipids, which lowers the permeability of the membrane. One adaptation by deep-sea animals to increase cellular permeability is to increase the percentage of unsaturated fatty acids. In a saturated fatty acid, all the carbons in the chain are linked by single covalent bonds. As you recall, a carbon can form four chemical bonds. If all these bonds are covalent (single), then a carbon could potentially attach to four other atoms. The term “saturated” comes from the fact that the carbon chain is loaded with hydrogens. If a carbon forms a double bond with another atom, it would bond with one less hydrogen. Thus, an unsaturated fatty acid has double bonds and is not “saturated” with hydrogens. The double covalent bond between adjacent carbons in an unsaturated fatty acid leads to a kink in the tails of the molecule. Thus increasing their concentration in the membrane leads to looser packing.

Pressure also selects for different enzymes. Changes in protein structure can influence their cellular function. Selection for rigidity is needed to counteract pressure and the resulting warping of proteins. Proteins contain hydrogen and disulfide bonds between different subunits and parts of the amino acid chain that dictate structure. Selection for proteins with increased bonding minimizes changes in shape due to pressure. Pressure can even make molecules more (or less) toxic. Urea is a good example: it becomes far more toxic as pressure increases. Deep-sea sharks, which like all sharks have a lot of urea in their blood, also have more of the protective chemical TMAO to offset this effect than their shallow-water cousins.

Pressure also does not favor air-filled volumes and sacs. The deepest diving submersibles require titanium spheres to hold the air-filled volume for their human inhabitants. For deep-sea animals, titanium is not an option, so most avoid having air-filled sacs. For example, deep-sea fish lack swim bladders. Other deep-diving animals like whales and seals have collapsible lungs to deal with extreme pressure (not to mention a whole host of other adaptations)!”

The post How Life Thrives Under the Ocean’s Crushing Pressure first appeared on Deep Sea News.

As I watched the monitor as we descend a 75-foot-tall chimney. Charcoal black to grey fluid is violently erupting from the top and several cracks along the chimney’s surface. You could see the shimmering sheen in the water, indicating that the temperatures were far above those of the surrounding, freezing abyss. Hydrothermal vents are home to the highest recorded temperatures on Earth. At oceanic ridges, where rocks are often brittle and fractured, cold seawater percolates down through Earth’s crust, gets superheated by magma, and rises back to the surface. Currently, the “Two Boats” vent in the Turtle Pits field along the Mid-Atlantic Ridge holds the record for the hottest hydrothermal vent, with fluid temperatures reaching up to 867.2˚F (464°C), nearly four times greater than the boiling point of water at 212˚F (100˚C). The extreme pressure prevents this boiling from actually happening.

At some vents lives the curious little worm, Alvinella pompejana. Discovered in the early 1980s by French scientists, the Pompeii worm is about 4 inches long with tentacle-like, scarlet gills on its head. Its name hints at its high-temperature habitat, being derived from the ill-fated Roman city of Pompeii, destroyed abruptly during an eruption of Mount Vesuvius in 79 A.D. The scarlet worm is found on the sides of hydrothermal vents, with its tube often reaching across the chimney to access some of the hottest vent fluids. The worms can be briefly exposed to 212˚F (100˚C) waters, although temperatures adjacent to the worm’s tubes more often range between near freezing and 113˚F (45˚C). In fact, the rear end of the species likely experiences extreme heat while the front end experiences extreme cold, making it the most eurythermal (capable of surviving a wide range of temperatures) species on earth.

How Alvinella pompejana survives in this boiling hot environment is still somewhat of a mystery. One theory is that the worm can keep itself cooler, between 68-83°F, by pulling cold water into its tube when it moves in and out, and with the help of bacteria that circulate the water around its body. This gray layer of bacteria covering the worm’s back, besides moving water, may also provide it with a sort of thermal blanket. The worm’s skin and connective tissue also have the most heat-resistant proteins known, thanks to their special structure. Additionally, the worm’s DNA has more triple bonds from guanine-cytosine (GC) pairs compared to other similar species, which helps it stay stable at temperatures up to 190˚F (88°C).

The post A Journey to the Hottest Place on Earth: Hydrothermal Vents and the Resilient Pompeii Worm first appeared on Deep Sea News.

We fly along the shoreline and notice dozens of dead urchins.  The brine’s high density, which prevents it from mixing with the ocean above, also means that oxygen is not mixed in, creating an anoxic deathtrap for unsuspecting respiring organisms.  As we continue to explore, a small, semi-submerged mound in the middle of the brine pool begins to pulse and vent.  As we maneuver the Global Explorer closer, we see hundreds of cavities all venting fluid.  We take a sample of mud around one of these pits, in hopes of capturing its invertebrate builder.  Later on board the vessel, we examine the sample and discover a type of worm, a sipunculid, half the size of hot-dog with the bright green, gold, and purple colors. Students in my research group begin almost immediately referring to it as the Mardi Gras Worm.  How can this worm survive in such a toxic place?

Both cold seeps and their chemical and geological relatives, hydrothermal vents, are rich in reduced chemicals, particularly hydrogen sulfide.  These chemicals are toxic.  Sulfide and oxygen don’t naturally coexist for long because they react spontaneously and rather aggressively. However, this sulfide also provides a unique energy source, by willingly donating electrons, to chemosynthetic microbial live. These microbes use this to fix carbon and produce food. This makes vents and seeps different than the rest of the deep in being largely independent of sunlight and the photic zone above.  Many organisms in these environments either feed on free-living bacteria or form symbiotic relationships with chemosynthetic bacteria to obtain their food. This makes life challenging for both microbes and the animals that depend on them, as they need both sulfide and oxygen.

Despite these harsh conditions, these unique ecosystems flourish, showcasing the remarkable adaptability of life in extreme environments.  The hydrothermal vent worms, the Alvinellids, build tubes projecting from chimney walls, giving their gills access to oxygen-rich water.  The other end of the tube can then access the vent fluids rich in hydrogen suflide.  Mobile predators like the crab, Bythograea thermydron can move between areas with and without oxygen. Ice worms, so names because they are found on methane ice in the cold seeps of the Gulf of Mexico, circulate oxygenated water around itself using its bristle-bearing appendages. The adaptations extend well into the biochemical level.  The massive vent worm, Riftia pachyptila and the Alvnellids contain hemoglobins, giving them bright red colors, which bind insistently to oxygen.

But once dealing with oxygen issue, how do these species survive the toxic sulfide and heavy metal soup of vents and seeps. One way means of survival for these organisms is prevent sulfide from even reaching sensitive tissues.  Creating sulfide barriers may mean creating thick tubes or cuticles to prevent the skin from encountering suflide. For example, the Pompeii worm, Alvinella pompejana, at hydrothermal vents secretes proteinaceous tube that it shares with bacteria. Animals that inhabit chemosynthetic habitats also often possess a specialized blood protein that binds to sulfide—forever—preventing it from mucking up the business of respiring oxygen.  At hydrothermal vents, metals reach such high concentrations they precipitate out of water.   These heavy metal solids form the impressive chimney structures of vents and even coat the tubeworm tubes and the shells of snails and clams.  Chemosynthetic organism have ways of dealing with this too.  Special metal-binding proteins, called metallothioneins, grab toxic metals and even grouping together to form little bodies or particles distinct from the rest of the cell. These consolidated and enclosed heavy metals then stay out of the way and do not gum of the cellular works.

Overall, the exploration of these deep-sea ecosystems reveals the astonishing resilience and adaptability of life in extreme conditions, offering valuable insights into the limits of biological diversity and the potential for life beyond Earth.

The post Surviving Toxic Havens first appeared on Deep Sea News.

“They got it!” echoed shouts down the hallways of the Research Vessel Atlantis in Fall 2018. The whole science crew knew what it meant: The elusive polychaete worm, seen numerous times during our deep-sea dives at the Pacific Costa Rica Margin, had finally been captured. Now, it’s been formally described in PLoS One.

The research cruise in question was one of three that surveyed the cold seeps off the coast of the Pacific Costa Rica Margin from 2017-2019. This region is a subduction zone – where one tectonic plate is subducting beneath another. This tectonic activity fuels cold seeps in the area, where chemicals are expelled from the ocean floor that can sustain chemosynthetic life. While seepage had been suspected in this region since 2002, these three cruises represented one of the most intensive sampling efforts in the area to date. One seep site in the region – “Mound 12” – is located about 1,000 m (3,280 ft) below the surface. While we had managed to collect a dizzying array of life here from snails, to tubeworms, to crabs, to mussels, one animal continued to evade our grasp: The Carpet Dragon.

            Okay, it’s not a dragon. It’s also not a flying carpet. But dive videos of individuals seen swimming just above the ocean floor sure looked a lot like both! As scientists aboard the ship didn’t know what it was and were fairly certain the species had never been seen before, the moniker stuck. At about 4-5 inches in length, it could be seen gliding past the cameras with undulating grace, its iridescent parapodia (paddle-like structures used for swimming) dazzling in the sub lights. First observed back in 2009, the Carpet Dragon had eluded capture for nearly a decade. This time, however, the operating team of the deep submergence vehicle (DSV) Alvin, vowed to change that.

            Several dives to Mound 12 yielded sightings, attempts at capture, but still no specimen. The science team was getting nervous. What if we had to finish our expedition with no dragon in tow? Then, on the day before Halloween in 2018, Alvin pilot Bruce Strickrott finally managed to capture a live specimen and bring it to the surface. The science team was buzzing with the news, anxiously awaiting Alvin’s ascent to the surface where we could finally see this specimen up close. We were not disappointed.

The Carpet Dragon, or Pectinereis strickrotti as it’s now officially called, is a polychaete annelid (“Annelida” = Broad animal phylum including all segmented worms; “Polychaete” = Broad class of marine annelids). Specifically, this worm sits within the family Nereididae de Blainville, 1818, which currently includes more than 700 species! While nereidids are found in both shallow and deep water, deep-sea and cave-dwelling nereidids share similar features of “darkness syndrome,” such as having reduced or no eyes and very long appendages. This species, however, is unique among all nereidids in having, among other things, parapodial projections near its head that are modified to function as gills, a hook-shaped acicula (= the strong internal bristle that adds structural support to the parapodia), and a fourth epitokal body region (most only have 3). These unique features not only mean that this is a new species, but also that it belongs in its very own genus, too! Its genus name combines the Latin word for comb (“pectinis”) with the name of the Family (“Nereis”) referencing its unique, comb-like gill structures. Its species name honors Mr. Strickrott, the Alvin pilot that finally captured the beast.

The individuals seen swimming around Mound 12 were found to be male epitokes – Free-swimming, sexually mature forms of polychaetes. Epitokes may form in two ways: (1) An sexually immature polychaete (an “atoke”) stays burrowed in the sand and buds off numerous reproductive epitokes to go and do its sexual bidding (think of it as going on dozens of one-night-stands without ever having to leave your couch), or (2) atokes go through the transformation themselves into a sexually mature epitoke. In both strategies, the epitoke dies once its gametes are released.

            Pectinereis strickrotti is just one example of the myriad of unknown species in the deep ocean, and it is believed that there are numerous undiscovered species of nereidids in the deep ocean just waiting to be described. The energetic hunt for the Carpet Dragon may seem silly, but was ultimately a testament to the enthusiasm, perseverance, and teamwork needed to propel scientific exploration forward. What might scientists find next?

Villalobos-Guerrero, Tulio F., et al. “A remarkable new deep-sea nereidid (Annelida: Nereididae) with gills.” Plos one 19.3 (2024): e0297961

The post The Carpet Dragon Takes Flight first appeared on Deep Sea News.

When whales die and sink to their watery graves, they bring to the seafloor bones rich in those fatty lipids. Thousands of bone-eating females, each just few millimeters high, will infest a whale carcass. So many will accumulate, the whale bones will appear to be covered in a circa 1970’s red shag rug-a rug that eats bones, has harems, and secretes acids, but otherwise a normal shag rug.  Originally, and with good reason, it was thought that Osedax was clearly a whale-fall specialist. The core of whale bones consists of a matrix rich in lipids – up to 60 percent.

But what about something wholly different?  Before the age of large marine mammals, large marine reptiles dominated the oceans. During the Mesozoic Era, rising to dominance in the Triassic and Jurassic periods, ichthyosaurs, plesiosaurs, and nothosaurs represented a diverse group of large marine predators terrorizing smaller creatures in the dark depths. The ichthyosaur Shonisaurus may have reached lengths of up to 21 meters in the Late Jurassic and Plesiosaurus may been 12–15 meters in length. The ancient sunken carcasses of these massive marine reptiles may have hosted ancient Osedax. We do know that prehistoric ichthyosaur falls are known to support communities similar to modern whale falls. 

Not to be outdone by other scientists in throwing random things on the seafloor to see what will eat it, in early 2019 I placed not one but three dead alligators on the seafloor in the deep Gulf of Mexico.  Alligators are nice modern analogues of the giant reptiles that once lurked in paleo-oceans and in my current state of Louisiana…well…readily available. And because we could, we place a packet of cow bones down there as well. 53 days later, my team and I visit the alligator carcass to find nothing but bones.  The reddish hue of fuzziness on them indicates Osedax are present.  On May 3, 2019, we overnight some of the collected bones out to California so Greg Rouse can inspect them in his lab and confirm their presence.  We wait patiently for an email from Greg.  On May 23, we get an email from him with the subject “Two new species :-)”. We are elated! Indeed, he finds females with well-developed ovaries and eggs.  Using genetics, he determines that the Osedax on the alligator and cow bones are both new species, previously unknown to science.

Fast forward to today when I get an email with the subject “Your species”. That Osedax from the alligator is named after me.

Osedax craigmcclaini n. sp. is named for Dr. Craig McClain, an esteemed deep-sea biologist and colleague who led the experimental alligator fall project (McClain et al., 2019) and provided the Osedax specimens for this study.

New Species of Osedax (Siboglinidae: Annelida) from New Zealand and the Gulf of Mexico

The post Introducing a New Species: My Namesake, a New Bone-Eating Worm first appeared on Deep Sea News.

A team of scientists recently wrapped up a 40-day research voyage (jealous!) from the Salas y Gómez Ridge to Rapa Nui, commonly known as Easter Island. Situated off the coast of Chile, this ridge is teeming with biodiversity and is being considered for designation as a high-seas marine protected area. Led by Drs. Erin E. Easton from the University of Texas Rio Grande Valley and Javier Sellanes from the Universidad Católica del Norte, the team meticulously studied 10 seamounts and two islands along the 2900-kilometer-long underwater mountain range. Their findings reveal distinct ecosystems on each seamount, including glass sponge gardens and deep coral reefs.

The post Hump Day Happiness: Dive into Deep-Sea Delights first appeared on Deep Sea News.

Xiao, Yunlu, and Haibin Zhang. ” Three new species and one new record of Deimatidae (Echinodermata, Holothuroidea, Synallactida) discovered in the South China Sea and the Mariana fore-arc area using integrative taxonomic methods.” ZooKeys 1195 (2024): 309.

The post New Deep-Sea Cucumber Has 100 Feet first appeared on Deep Sea News.

Enter Simoniteuthis michaelyi, a newfound taxon that has captured the attention of researchers worldwide. This remarkable creature, based on a nearly complete pen accompanied by a head-arm complex, is a brilliantly preserved fossil.

What makes Simoniteuthis truly intriguing is its unusual arm crown, boasting only four arm pairs instead of the expected five. This anomaly challenges our understanding of vampyromorph anatomy.

But the surprises don’t end there. Examination of the specimen’s mouth region reveals evidence of predation on two bony fishes. The two animals died in the act of predation, i.e. one had caught the other and had begun to nibble on it, when they possibly sank into hypoxic waters and suffocated.

Unlike its modern descendant, Vampyroteuthis infernalis, Simoniteuthis inhabited shallower waters, reminiscent of Mesozoic vampyromorphs. This divergence in habitat and hunting behavior offers valuable insights into the evolutionary trajectory of these captivating creatures.

Through meticulous analysis of the fossil record, researchers speculate that vampyromorphs began a vertical migration into deeper waters, possibly driven by shifts in feeding behavior, as early as the Oligocene epoch.

Fuchs, Dirk, Robert Weis, and Ben Thuy. “Simoniteuthis, a new vampyromorph coleoid with prey in its arms from the Early Jurassic of Luxembourg.” Swiss Journal of Palaeontology 143.1 (2024): 1-10.

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In the profound darkness of the ocean’s depths, organisms face a choice concerning their visual capabilities. Some species evolve specialized eyes that grow to astonishing sizes, as seen in creatures like the giant squid or owl fish. Alternatively, there’s the option to abandon the concept of eyes altogether. It’s the latter scenario that introduces us to an intriguing case: the “blind lobsters,” a peculiar group of 38 lobster-like crustaceans known as Polychelidae. These creatures exclusively inhabit the deep sea, dwelling at depths exceeding 5,000 meters (16,000 feet). Members of this group typically exhibit either absent or vestigial eyes, along with reduced or entirely absent eye stalks.

However, their lack of eyesight isn’t the most remarkable aspect of these creatures. Unlike typical lobsters, which possess two claws, Polychelids boast up to 5 pairs of claws. They feature two larger claws, followed by four smaller yet equally intimidating ones. The name of the group, “Polycheles,” derives from the Greek words meaning “many-clawed.”

While one might assume scientists are primarily intrigued by the blind, multi-clawed nature of these creatures. But they are complex. Scientists and Poychelids alike.  Polychelid bodies provide evidence of a transition from shrimp-like to lobster-like forms. Despite their lobster-like appearance, they lack certain primitive characteristics, such as a pointed telson (back-end) instead of the rounded telson found in typical lobsters. This appearance is similar to another group of unusual crustaceans, Eryon, dating back to the Jurassic and thus making Polychelids somewhat of a living fossil similar to the Coelacanths.  Yet intriguingly Eryon dwelled in the warm shallow seas of the Jurrassic.  The question of why they migrated to the deep sea remained unanswered—did they seek refuge in these depths, as suggested for other deep-sea taxa? Recent fossil and genetic evidence suggests that they have always inhabited these depths since their evolutionary origins in the middle Jurassic period.

Chang, Su-Ching, Shane T. Ahyong, and Ling-Ming Tsang. “Molecular phylogeny of deep-sea blind lobsters of the family Polychelidae (Decapoda: Polychelida), with implications for the origin and evolution of these “living fossils”.” Molecular Phylogenetics and Evolution 192 (2024): 107998.

Bezerra, Luis Ernesto Arruda, and Felipe Bezerra Ribeiro. “Primitive decapods from the deep sea: first record of blind lobsters (Crustacea: Decapoda: Polychelidae) in northeastern Brazil.” Nauplius 23 (2015): 125-131.

The post The Many Clawed, Blind Lobsters of the Deep first appeared on Deep Sea News.

Jack and squat is known about free-living flatworms form the deep sea. Their fragile bodies are unlikely to be collected successfully in dredges and trawls. This means that outside of ‘potential platyhelminth’ from a wood fall and deep record of another species little else is known.

A new study adds to our limited knowledge of these beasties. Flatworm egg capsules were retrieved from rocks found approximately 6200 meters deep in a trench in the northwestern Pacific. Despite each capsule being a diminutive 3mm in size, they housed anywhere from 3 to 7 individuals. Through the application of genetic tools, the researchers identified a new species within a group previously only observed in shallow waters.

Kakui, Keiichi, and Aoi Tsuyuki. “Flatworm cocoons in the abyss: same plan under pressure.” Biology Letters 20.1 (2024): 20230506.

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