“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

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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

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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 this luminescent tapestry, sea cucumbers emerge as unexpected stars. While we might not associate these echinoderms with bioluminescence, they contribute significantly to the underwater light show. Interestingly, in shallow waters, only a mere 1% of species can emit light, whereas the seafloor teems with bioluminescent activity, showcasing the radiant abilities of over 50% of its inhabitants. Venture to the depths of one kilometer, and you’ll find that luminous sea cucumbers constitute an astonishing 99% of all sea cucumbers.

Research by Manabu Bessho-Uehara, Jerrome Mallefet, and Steven Haddock have cast light on the bioluminescent secrets of sea cucumbers. Documenting not only 42 known species of glowing sea cucumbers but also six independent evolutions of bioluminescence within the sea cucumber lineage. The earliest illuminated sea cucumber may have been nearly 400 million years to the Devonian era, coinciding with the establishment of the first land animals.

While the precise details of how sea cucumbers produce their blue to greenish bioluminescence remain a mystery, the process involves a small organic compound known as luciferin. This compound is catalyzed to oxidize by an enzyme fittingly named luciferase.

The question of why sea cucumbers, or holothurians, need bioluminescence remains unanswered. Like other organisms that exhibit this phenomenon, the glow may serve various purposes. From communication to startling, misdirecting, and warning predators, to attracting, stunning, or illuminating prey, and even facilitating mate recognition—the role of bioluminescence in sea cucumbers raises intriguing hypotheses. One such theory suggests that it functions as a burglar alarm, attracting larger predators to deter potential threats—a fascinating manifestation of the age-old adage, “the enemy of my friend is my friend.”

Photos from : Bessho-Uehara, Manabu, Jérôme Mallefet, and Steven HD Haddock. “Glowing sea cucumbers: Bioluminescence in the Holothuroidea.” The world of sea cucumbers. Academic Press, 2024. 361-375

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Describing another family is literally another level.  Above the species in the taxonomic pecking order, we have the genus and then the family level.  Introducing a new family requires something truly unique. A case in point is a new creature from the remote depths of the Hikurangi Plateau, off the eastern coast of New Zealand.

The new family called, Basoniscidae for “basal” position in evolution of isopods and because the common word for isopods, wood lice, or sow pugs is “oniscus”. The species is Basoniscus hikurangi and displays features from two distinct families—the shallow water Joeropsididae and the deep-sea Haploniscidae—giving it is basal position.  For as enigmatic deep-sea species, it is rather amorphous.  Unlike its more common counterparts, this broad-bodied, eyeless isopod reveals an intriguing fusion of features typically associated with two different families. The distinctive features of the broad body, thin flat marginal flanges, and minute curved robust “bristles”, coupled with the presence of robust claws on the walking legs – particularly the ventral claw – hint at a fascinating adaptation in these isopods. It is conceivable that these unique characteristics equip them with the ability to tightly cling to surfaces. This behavior is particularly suggestive of an affinity for hard volcanic surfaces, mirroring the conditions from which the specimens were originally collected.

Beyond its taxonomic significance, this discovery sheds light on the underexplored realm of rocky hard substrates in the deep sea. The limited sampling of such substrates highlights a significant and the continued  gap in our understanding of all deep-sea ecosystems.

The post A New Deep-Sea Family of Roly Polies first appeared on Deep Sea News.

The fossil record hints at a trend of shallow origins diversifying into the depths for certain marine organisms. However, conflicting results arise from approaches based on genetics, some supporting an onshore-offshore evolutionary pattern while others propose the opposite.

Enter the world of scleractinian corals, the stony or hard corals, a perfect testing ground for studying biodiversity across massive depth gradients. These corals span a wide depth range, from the ocean’s surface to depths surpassing 6,000 meters. How these creatures spread and settle in different areas, influenced by changes in their physical traits, help us understand the complex ways they’ve evolved over time and in response to the deep sea Take Micrabaciidae, a family of scleractinian corals. They have a slender, porous skeleton covered entirely by tissue—a probable adjustment for survival in the deep sea, where crafting a larger, sturdier skeleton becomes challenging due to lower aragonite, a form of calcium carbonate needed to build shells and skeletons, levels.

Half of the scleractinian corals form vibrant shallow reefs, while the other half, independent of the photic zone, thrives in cold waters across diverse regions and depths. This diversity not only paints a vivid picture of the coral world but also holds keys to understanding the origins of deep-sea life and diversity.

A new study by Campoy et al asks four key hypotheses about evolution of scleractinian corals

1. Origin of these corals might trace back to the upper bathyal zone (200–1000 meters). The steep and varied nature of this zone creates distinct environmental conditions, potentially fostering diverse adaptations across depths and serving as a catalyst for biodiversity
2. Lineages where symbiosis or coloniality emerged saw heightened rates of colonization. If these traits indeed bolstered the corals’ ability to spread, their emergence should align with faster colonization rates.
3. A prolonged evolutionary trend favoring faster colonization toward shallower waters. This hypothesis assumes that the common ancestor of these corals lacked symbiotic relationships and lived solitarily, suggesting that symbiosis inherently links to the sunlit zones, with colonial species generally occupying shallower depths compared to solitary ones.
4. Evolutionary forces predominantly shaping species’ depth ranges occur more significantly in shallower waters. As depth increases, environmental variability and interactions among species decrease, potentially slowing down the evolutionary pace through deeper zones.

The intricate dance of evolution (too much?) reveals itself through deep-water origins, surviving multiple geological changes and even global anoxic events. Specifically, the results show that the order Scleractinia originated 415.8 million years ago somewhere between 229–2287 meters depth. The emergence of the Scleractinia order in the deep sea aligns with a pattern of evolution from offshore to onshore and not providing strong support for upper bathyal zone origination as in hypothesis one. However, various coral lineages spread and settled at varying rates across different depths. Moreover, the pace of colonization slows at greater depths, underscoring the vulnerability of these ecosystems to further and current human exploitation.

Campoy, Ana N., et al. “Deep-sea origin and depth colonization associated with phenotypic innovations in scleractinian corals.” Nature Communications 14.1 (2023): 7458.

The post From Depths Unknown: Deciphering the Origins of Deep-Sea Biodiversity first appeared on Deep Sea News.

Connecting the oceans to land are numerous carbon highways.  These conduits bring food from land to the ocean, supporting an abundance of life.  Our group explores these carbon chains and explores some potential methods of carbon delivery to the deep.  Thus, alligators on the abyss.

At first it may seem fanciful that an alligator carcass might find its way to the deep.  However, dozens of species of alligators and crocodiles are found across the globe, in high numbers, and often in coastal areas.  Through either their normal migrating or foraging activities, or during flooding events, individuals may be found offshore in the ocean.  If one of those individuals meets an unfortunate end, it may fall to the seafloor.

In prehistoric times, the impact to the deep oceans could have been even larger, as large reptiles such as ichthyosaurs and plesiosaurs dominated the sea. Deploying a reptile in the deep sea today may reveal the animals that specialized on the carcasses of long-extinct ancient emperors of the sea.

Earlier this year, our research group placed three alligator carcasses 1.5 miles deep on the seafloor of the Gulf of Mexico in the first-ever alligator fall experiment.  Each of the three alligators met a different fate.

The first alligator had been on the bottom of the ocean for less than 24 hours. Despite the tough hide of the alligator, scavengers quickly got through and began to gorge themselves on the flesh of the alligator. Football-sized animals called giant isopods, relatives of rolly pollys or pillbugs, penetrated the hide in this short time-frame.  This demonstrates the speed and precision with which deep-sea scavengers can utilize any carbon source, even food from land and freshwater systems.

A little over 60 miles to the east of the first alligator, the second alligator had been sitting on the seafloor for a little over a month and a half.  All the soft tissue of the alligator had been removed by scavengers.  A small animal called an amphipod was still darting around looking for scraps, but the only thing that remained was a skeleton.  All of the soft tissue had been consumed. The spine curved just as it had been left.  A depression in the sediments indicated where the full body once laid.  The skull was turned over, likely by scavengers while picking at the flesh on the skull.

A fuzzy carpet covering the bones of the second alligator represented a brand-new species, previously unknown to science.  These zombie worms, or Osedax, colonize the bones of many types of vertebrates and consume the lipids within.  This was the first time zombie worms had ever been observed in the Gulf of Mexico or from an alligator fall.  They also demonstrate yet another pathway in which carbon from land makes its way into deep-sea food webs.

Another 60 miles east lay the third alligator.  It had only been eight days since it was laid on the seafloor.  As the camera panned to the marking device, a floating bucket lid attached to a rope like an underwater flag, it became clear that the alligator was missing.  All that remained where it had been dropped was an alligator-shaped depression in the sediments.  Drag marks in the sediment paved a path to what remained of the alligator fall.  An animal dragged this alligator 30 feet and left only the 45-pound weight and rope.  The rope had been bitten completely through. To consume an alligator, and create this disturbance, the animal must have been of great size.  We hypothesize that most likely a large shark, like a Greenland shark or sixgill shark, consumed this alligator whole.

Three alligator falls in the abyss met three very different ends, from being consumed by football-sized cousins of rolly polys, to zombie worms eating their bones, to a large shark dragging it away and consuming it whole.  This research has given us a glimpse into what impact large reptiles had in past oceans, as well as the role they play today.  It is clear that deep-ocean scavengers have no qualms about successfully and quickly consuming food that originated on land or freshwater.

Read more about this research in our group’s recent publication in PLOS One: “Alligators in the abyss: The first experimental reptilian food fall in the deep ocean.”

The post Alligators in the Abyss: Part 2 first appeared on Deep Sea News.

From the darkness emerges a boot. An old leather, steel-toed, work boot. It shouldn’t be there resting on the seafloor nearly two kilometers deep. I’m speachless. Even knowin this was going to be one of the toughest dives of my career, I’m still not prepared.

Seven years prior in 2010, Marla Valentine and Mark Benfield were the first scientist to visit the deep-sea floor after the Deepwater Horizon accident. On 20 April 2010, and continuing for 87 days, approximately 4 million barrels spilled from the Macondo Wellhead making it the largest accidental marine oil spill in history. Just months after the oil spill, Valentine and Benfield conducted video observations with a remotely operated vehicle (ROV) of the deep-sea impact. Overall, they found a deep-sea floor ravaged by the spill. Much of the diversity was lost and the seafloor littered with the carcasses of pyrosomes, salps, sea cucumbers, sea pens, and glass sponges.

Researchers continued to find severe impacts on deep-sea life. The numerical declines were staggering within the first few months; forams (↓80–93%), copepods (↓64%), meiofauna (↓38%), macrofauna (↓54%) and megafauna (↓40%). One year later, the impacts on diversity were still evident and correlated with increases in total petroleum hydrocarbons (TPH), polycyclic aromatic hydrocarbons (PAH), and barium in deep-sea sediments. In 2014, PAH was still 15.5 and TPH 11.4 times higher in the impact zone versus the non-impact zone, and the impact zones still exhibited depressed diversity. Continued research on corals found the majority of colonies still had not recovered by 2017. However, studies examining the impacts of the DWH oil spill on most deep-sea life ended in 2014.

This gap in knowledge on the lingering impacts of one of the largest oil spills of all time is why I sit here in this cold, dark, ROV control room staring at a work boot in the abyss. A year prior, I had reached out to Mark Benfield about replicating his ROV methods and locations. I am here seven years after his study beginning to replicate his first video transect.

Within minutes of reaching the seafloor with the ROV, every scientist on the vessel staring at monitors showing live video from remote seafloor knew something was wrong. As Mark Benfield, Clif Nunnally, and I report in a new open-access article, the deep sea was not recovering at the impact site.  The seafloor was unrecognizable from the healthy habitats in the deep Gulf of Mexico, marred by wreckage, physical upheaval and sediments covered in black, oily marine snow.

Near the wreckage and wellhead, many of the animals characteristic of other areas of the deep Gulf of Mexico, including sea cucumbers, Giant Isopods, glass sponges, and whip corals, were absent.  What we observed was a homogenous wasteland, in great contrast to the rich heterogeneity of life seen in a healthy deep sea.

Conspicuously absent were the sessile animals that typically cling to any type of hard structure in an otherwise soft, muddy habitat.  Hard substrate in the deep sea is a valuable commodity but at the Deepwater Horizon site metal and other hard substrates were devoid of typically deep-sea colonizers.

The seafloor at impact site was characterized by high numbers of shrimps and crabs.  Crabs showed clearly visible physical abnormalities and sluggish behavior compared to the healthy crabs we had observed elsewhere.  We believe these crustaceans are drawn to the site because degrading hydrocarbons serve as luring sexual hormone mimics. Once these crustaceans reach the site they may become too unhealthy to leave much like those prehistoric mammals and the Le Brea tarpits.

The ROV dive began with a boot belonging to one of the workers on the Deepwater Horizon rig. The dive ended at the wellhead, now capped with a memorial to those workers who lost their lives. A dive bookended with reminders of the human tragedy of the oil spill. The narrative that unfolded between these was an environmental catastrophe. In an ecosystem that measures longevity in centuries and millennia the impact of 4 million barrels of oil continues to constitutes a crisis of epic proportions.

Valentine, Marla M., and Mark C. Benfield. “Characterization of epibenthic and demersal megafauna at Mississippi Canyon 252 shortly after the Deepwater Horizon Oil Spill.” Marine Pollution Bulletin 77.1-2 (2013): 196-209.

McClain, Craig R., Clifton Nunnally, and Mark C. Benfield. “Persistent and substantial impacts of the Deepwater Horizon oil spill on deep-sea megafauna.” Royal Society Open Science 6.8 (2019): 191164.

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