The Life That Lives Below The Abyss

Added: 2026-05-05

[00:00:00]Here's a fun little thought experiment.

[00:00:02]Imagine someone hands you a camera, shoves you in a submarine that hopefully was not designed by a billionaire, and tells you to film whatever lives at the very bottom of the ocean. Simple enough, right? Well, not really. Because as you start sinking, you quickly realize that the ocean is not some uniform blue wet thing that most people think it is.

[00:00:18]Instead, rather being a perfect replica of Subnotica. In other words, a place that gets progressively more alien the deeper you go, despite you technically getting closer to the Earth, which does kind of make you think that maybe it's the surface that's the weird part. But I digress. Now, near the surface, everything is fine. Fish are doing fish things. Kelp is swinging. Sunlight is plentiful. Life is good. But a few hundred meters down, the light starts fading, and by a kilometer deep, or 3,280 ft, your screen goes completely blank. And now, every additional meter of depth comes in more and more pressure pushing on the hole. And to put this into perspective, it would kind of be like walking down an endless staircase while someone keeps stacking SUVs on your back. One for every 10 meters or 33 feet to be specific. And by 4 km or 13,000 ft, the water becomes as cold as the inside of your fridge. Roughly 4° C or 39° F. And that around 6 km or 19,700 ft, the floor might suddenly drop away and you're left staring into a trench that goes deeper than Mount Everest is tall. And down in that fissure is permanently dark, obviously barely above freezing. and the pressure crusher submarine like a soda can. And yet animals still live there and not just a few random weirdos either, but rather entire communities just doing their thing. So again, what actually lives at the very bottom of the ocean? Well, buckle up friends, because the answer is equal parts bizarre, horrifying, and honestly kind of beautiful. But before we meet the residents, we need to understand the landlord because the environment down here dictates everything. No light means that vision is basically optional, and bioluminescence becomes a prized gift.

[00:01:48]Near freezing temperatures and low productivity lead to metabolism slowing way down. So animals that would normally zip around in shallow water instead glide through the dark like they've got nowhere to be. Which, to be fair, they don't. And then there's the pressure, the ultimate gatekeeper. You see, hydrostatic pressure literally squishes water molecules into your proteins and destabilizes them, which is just about as bad as it sounds. And so in order to combat this, many deep sea organisms stuff their cells with molecules called pasolytes, which are molecules that help stabilize proteins against high water pressure, such as trimethylamine and oxide, or TMAO for short. But here's the thing, that strategy only works up to a point. Past 8 km or 26,000 ft, you would need so much TMAO in your body that you'd essentially turn to a jar of pickled herring. And this is exactly why the deepest fish on Earth, the hallel snail fish, maxes out around 8 km, more or less. So, 26,000 ft. And speaking of the Hatal snail fish, if this little guy was a center of a sports documentary, we'd be exposing this guy for gene duplication like it was performance-enhancing doping on steroids. Pun intended. And why? Because this fish is absolutely loaded with extra copy of genes to protect against DNA damage and pump out those molecular protein bodyguards, i.e. TMAO. But what it gained to what is essentially water resistance, it lost in well, basically everything else. I mean, just look at it. It's in the name. A fish that's turned into a snail. Enough said. And what you can't see is that this guy also essentially cannot smell or see, having dished many genes for vision and olfaction. In addition, their skeleton is bone that's not fully bone, undergoing something called incomplete mineralization, which is actually pretty clever as it's a design to help with buoyancy control, but still allows for enough rigidity that it can anchor muscles. And speaking of those muscles, they are so dang watery that if you brought one to the surface, it would pretty much literally collapse into a puddle, which is both sad and kind of hilarious. And again, since the bottom of the ocean is all like, "Hello, darkness, my old friend." Their vision is, like I said, very bad. But what they did invest in besides just the water resistance is a stomach that has been described as inflated, playing a role in their feeding. And the reproduction is pretty much just as weird as the rest of their body. As females lay a small number of unusually massive legs, likely reflecting increased investment in more developed offspring. And it's a slow but sound strategy. Fewer babies, but bigger ones. So, they're definitely going for quality over quantity here. But hey, when you're the apex predator of the hedle zone, you can afford to be more picky with your babies. And yes, you heard that right. These gooey translucent little guys that look like they'd lose a fight with the strong current are actually the top dogs or top fish of the deepest part of the ocean.

[00:04:21]They slurp up crustaceans like it's nothing and nothing down there messes with them. So, got to give respect where it's due. But that being said, since they are the apex predator, that obviously means that the snailish isn't the only thing or fish brave or crazy enough to live down here, though it is one of the deepest. In the upper reaches of the hallel zone, you can find certain grenaders cruising just above the sediment. These are also called rat tail fish. And honestly, one look at them tells you why. They've got this enormous head, oversized eyes, and a body that tapers into long whip-like tails. But this all said, rat tails is actually not a specific genus, but rather a family, the macro day. And it includes over 350 species and is one of the most abundant fish groups in the entire deep sea. And fun fact, they're actually relatives of cod. But unlike cod, they look hecking weird and at least some taste of their name suggests, apparently being considered completely unpalatable. But I guess that kind of makes sense seeing how deep in the ocean these guys can live with one species the corphenoidis yini having been spotted at 7,259 m or 23,815 ft in the Japan trench making it the deepest sighting of any fish with a swim bladder. And going back again to palletability, the way these guys find food is pretty impressive. They've got a very well-developed lateral line system which helps with detecting prey through motion. And they carry chemosensory barbles under their chins that work like a pair of twitchy sensing whiskers, helping find worms and hidden nurstations in the sediment. And like I alluded to, grenaders have swim bladders. And in many of them, they use the muscles attached to them to produce sound, likely playing a role in their courtship. But what that also means is that when you're in the complete darkness of the bottom of the ocean, you might suddenly just start hearing this drumming, rumbling sound coming from somewhere in the black, which is not exactly a comforting thought. And if they could, they probably would eat you with them being the opposite of picky eaters, eating poly keed worms, crustaceian, squid, fish, echinoderms, and pretty much anything that's already dead. So whatever the trench provides, they'll take it. And at least one species, coripinoidis armatus, is thought to be selperus, which is a fancy way of saying that the adults die after a single spawning event. So, they pretty much spend their whole lives growing, eating, and surviving in one of the most extreme environments on Earth, and then they reproduce once and die, which sounds like that's kind of a skill issue. Now, on the flip side, other grenadier species are the opposite, living for decades and not even reproducing until the 20-year mark. And then there are other fish that look like them kind of, which actually push even deeper than the rat tails, the cusk eels. Now, despite the name, these are not eels at all. They're instead members of the family ofiday being completely unrelated to true eels of the order and guilforms but they look eish so close enough. And what's interesting is that one species the abyss of Bratula Galath holds a disputed but widely cited record as the deepest fish ever captured having been trolled from approximately 8,370 m or 27,460 ft in the Puerto Rico trench back in 1970. And I say disputed because the net they used wasn't a closing net, which means the specimen could have theoretically been scooped up on the way back to the surface rather than being captured at the actual bottom. So at least personally, I still consider our snailfish friend as the true winner here. But whether or not the record stands, kuskills are absolutely confirmed inhabitants of the Hadel zone.

[00:07:31]Now, interestingly, they're are solitary animals, but that only really applies to their own kind, with them instead being noted to sometimes associate with tubeworms. So if you think you're the type of person to shun other people's company, imagine disliking your kind so much that you choose to associate with worms instead of other people. Yeah. Now physically, unlike the snail fish, their skeletons are still well oified, meaning actual hard bone instead of somewhat non-mineralized bone. They eat poly cage worms, amphipods, and isopods. And their strategy is basically just to hide when they're not looking for food. often being found in crevices, caves, and invertebrate communities, as I just mentioned, with some observations of kusky even showing they live inside in different invertebrates such as oysters and sea cucumbers, which by the way, I've seen a diver put one in their mouth. And uh I would not recommend that. Now, below the snail fish's depth limit, which again is around 8 km or 26,000 ft, fish pretty much cannot exist anymore. But don't get it twisted. That does not mean that life just stops. Oh no. Below that line, skeletons give way to well, not skeletons, instead being exoskeletons, kitan, shells, and just soft stuff. And one of the rulers of these depths are amphipods, which fill a niche somewhere between garbage man and wood chipper, which sounds weird. So, let me explain. Takeia gigas for example. It's modest in length, being neither small nor particularly giant.

[00:08:52]But it strangely wields enzymes that can digest cellulose, manin, and xylin, which in plain English means it can eat wood or plant material, which doesn't really make sense considering it lives in the bottom of the ocean. But here's how it works. Sometimes a log will eventually over probably a very long period of time tumble into a trench and then that's when these amphopods descend on it and carve it up, converting the cellulose directly into glucose. And what's really crazy when you think about it is the fact that wood from the surface supposedly ends at the bottom of the ocean so often that animals have literally evolved to take advantage of it. Pretty nutty. But this guy is not the only freak in the bottom of the ocean as then there is Alyssella Gigantia which evidently takes the concept of deep sea gigantism very seriously as this amphipod can reach lengths up to 34 cm or 13 in which might not sound like much until you remember that other amphipods are sometimes only 1 mm long. So in other words, over 300 times smaller. And unsurprisingly, its size has somewhat made it the top dog, or at least not the bottom dog. Seeing that unlike other amphopods in this depth, who are generally red or orange, which is an adaptation that basically works to camouflage at this depth, they are white, meaning they lack camouflage and is likely a reflection of a lack of predators. And speaking of eating, or rather not getting eaten, when food arrives, i.e. dead stuff. These things swarm like piranhas to blood, which is kind of creepy when you see a video of them, not going to lie. But as I alluded to, amphipods are not the only crustaceians in the trenches. And this next animal actually changed our understanding of, well, stuff. Now, before 2009, scientists believe that decapod crustaceans, which is the group that includes shrimp, crab, and lobsters, were completely absent from the Hadel zone. Like zero representatives. It was essentially considered subtle science, a fact, a universal truth, if you will. But then someone dropped a baited camera in a couple of trenches like the Japan and Mariana's trench. And um well that quote unquote truth quickly changed as what the cameras revealed was the bentimid prawn bentimus crenatus casually patrolling the depths well below they were supposed to. And on top of that they were filmed doing something rather unexpected. Instead of going for the bait themselves they were instead actively praying on the smaller scavenging amphopods that had swarmed in for a meal. just plucking them off a carcass like someone picking shrimp off of a buffet, which is funny because, well, they're shrimp. And since these guys, more families, species, and genus, have been discovered. And here's a cool detail. Some deep sea decapods are suspected of producing bioluminescent secretions from their mouth. In other words, basically vomiting up glowing clouds, which is likely done to startle predators. Kind of like opening the windows on a vampire and being like, "Back, foul beast. Back." So, yes, life down here is odd as odd can be. But if you thought it couldn't get any weirder, allow me to introduce you to the xenophores, which are, and I need to set you down for this, single cells. Yep, you heard that right. This thing is one single cell, despite seemingly being way too big for that to be true, with some species like sirina, fragilema, reaching up to 20 cm or 8 in in diameter. And what they do is that they essentially create exoskeletons called tests out of literally whatever is in their surroundings. sand grains, shells of dead organisms, etc. Just whatever is left around in the neighborhood with different species preferring different things. And speaking of neighborhoods, on the rocky walls of the trenches where the substrate is hard enough to grip, you'll find something that looks like it belongs in someone's garden, not at the bottom of the ocean. And that is stocked kryinoids, also known as sea lillies.

[00:12:19]And these guys anchor themselves to the rock and just wait for food to drift by.

[00:12:23]Each one is a slender stock crowned with feathery arms that fan out in the current. And they look pretty much exactly like flowers, which is kind of unsettling when you realize that they're in fact animals. And their lineage stretches back all the way to the Ordishian period. In other words, over 400 million years ago, being living fossils in all senses of the term. Now, you might have seen these guys before, and most people usually associate kryoids with shallow reefs. But the species in the family back have been photographed alive at over 9,000 m or 29,500 ft deep in the izo trench off of Japan. And the deepest known species, Bathocrinus Kurilli, was collected around 9,715 meters or roughly 31,900 ft. And that is obviously deeper than any fish can go. Meaning that a creature, nay, an animal that looks like a freaking flower, is living in places that would kill literally every single fish on Earth. And paradoxically, these deepest kryoid populations actually appear to be denser than their shallower relatives. possibly because the trench funnels organic material into a narrow channel where filter feeders can intercept it more efficiently. And so that also means the deepest, darkest, most hostile parts of the ocean has more living flowers per square meter than the quote unquote nicer neighborhoods, which I say to that up yours HOAs. Now, with all of this said, despite these neighborhoods being incredibly isolated from yours truly, us, the deep sea is not immune to what we do at the surface.

[00:13:46]And when researchers have mapped debris in deep trenches, they found plastic bags, fishing lines, and nets deeper than 10 km or 33,000 ft. And microplastics have been found in Mariana Trench sediment at more than 2,000 plastic particles per kilogram of sediment, which is absolutely insane when you realize that these are comparable to levels measured in heavily polluted beaches and coastal habitats.

[00:14:07]And uh I don't think I need to tell you, but that's very, very bad. And then there's deep sea mining, which has been proposed as a way to harvest metals used in batteries and electronics by stripping kilometers of seabed. And ignoring the actual damage to the places where this occurs, it would also kick up enormous sediment plumes that would devastate marine ecosystems simply because of all the material that's being kicked up. with one study that simulated four weeks of mining in coral communities, finding that as the weeks progressed, the coral, which are animals mind you, experienced progressive loss in tissue when necrosis occurring and then with death of all coral by the end of the experiment. And let me just reiterate that experiment was for 4 weeks, just four. And what's truly disturbing is that one study in 2025 found that a mining experiment that occurred over 40 years ago still had visibly negative impacts on the environment four freaking decades later.

[00:14:58]meaning disturbances could take centuries to recover from if they recover at all. So in other words, just like most of our planet, our ocean, our waters, that beautiful blue which is a hallmark of our planet is in trouble.

[00:15:10]But there are people trying to make a difference. One of those being Oceanana, an organization founded because one study found that only 0.5% of all resources spent by environmental nonprofit groups in the United States went to ocean conservation. And from what I can tell, they're one of the only large organizations focused exclusively on ocean policy advocacy at an international scale, which is important as policy persists beyond just one fishing cycle. And thus far, they campaign in countries controlling one quarter of the world's wild fish catch and aim to expand to 50% within a decade. So yeah, I'm going to be dropping a link to the pinned comment.

[00:15:42]But despite all these problems, the thing that keeps me going is that every single expedition to what is basically the bottom of the planet still comes back with something nobody expected. In 2022, robotic lander recorded snail fish from nearly transparent bodies swimming at record depths. In 2025, scientists identified certain enzymes and microbes that function at pressures that would crush a submarine, thus allowing them to survive in this cold, high pressure environment. They watched octopuses brood and protect eggs for years, meaning the same clutch that is, etc., etc. So, at the trench bottom, where we finally stop, what's revealed is an ecosystem that looks nothing like the barren wasteland that people imagine.

[00:16:17]And we've barely scratched the surface here. Well, technically opposite of the surface, but you know what I mean. So, the question isn't really what lives at the bottom of the ocean. The question is what else is down there that we have not found yet? And given what we've seen already, I'd say the answer is probably going to be even stranger than we think.

[00:16:33]Thanks for watching and until next time.