Testing My Thalassophobia Diving in the Open Ocean (at Night)

I'm in the middle of the ocean and there's 500 meters of water below me. And in this video, I'm going to be testing my thalassophobia. Diving in the day and at night to see what crazy creatures are swimming around in the blue. Whoa, what is that thing? Thalassophobia is an extreme fear of deep water. If you've got it, good luck watching this video. Home to only 10% of all marine life, the open ocean is like a desert. Vast, empty and almost lifeless. Whoa, what is that? So this here is a sea butterfly and it's a type of shellless mollusk or snail. However, whilst these sea butterflies are harmless, other creatures that drift in the blue are armed with tentacles covered in stinging nematocysts. So this Siphonophore is a colonial organism. And as you can see, we've got some kind of brain up here and then all of these things are covered in stinging cells. So we definitely need to stay away from this guy. And it actually looks like this one's using them as a lure. It's trying to lure fish in, sting them and then probably eat them. Ah, I think it's attached to me. If you think this Siphonophore is weird, wait until you see what we filmed at night when trillions of planktonic species rise up from the deep ocean to feed. Out in the vast blue, all life is instinctively drawn to structure, seeking safety, food and community. And as such, anything that floats on the surface is a magnet for life. So this thing here is a fad, otherwise known as a fish aggregating device. And you can see where it gets its name from. Now fads work because they play on something called figmataxis, which is when fish and other animals are drawn towards structure. And they do this because it provides shelter. And it's also a place where they can find food. And this one here is covered in all sorts of critters. These schooling fish are large-scaled pteropods. They find comfort in large numbers close to structure. And they're not picky. Whoa, look, they're attracted to my 360 camera. These pteropods spend most of their lives balled up underneath the fads, only venturing out to feed. The large ropes that anchor the structures to the ocean floor are likely their favourite feeding spots. But they also won't turn down other food items that drift past in the blue. Oh, and these pteropods are now feeding on the algae on this plastic cup. Many other species also hide in and amongst the floating structures. Although for a lot of them, they're not here by choice. Juvenile batfishes, drummers and schooling sergeant majors prefer coastal habitats and were perhaps pulled here by strong ocean currents. Luckily, these structures offer a lifeline. However, they make sure to not venture too far from cover, as the fads are also prime hunting grounds for ocean predators. Whoa, el macko jack. Look at this guy go with his black stripe across his eyeball. And this guy is a jack or a trevally. And these fish are pure muscle. They're super powerful. When he's a bit bigger though, he'll definitely be coming back here to eat all these small fish. Fish that spend most of their time in open water are said to be pelagic, swimming endlessly in search of food. They use their eyes and inner ears to pick out an easy meal in the sea of blue and it's possible to lure them in. So we've just attached this flasher line to the fad and as you can see, it's covered in all these flashing lures which will hopefully draw in some big pelagic fish. Although at the moment, it's just blue everywhere. Guys, if you've got thalassophobia, look away now because there's the surface and there's the bottom or lack of it. But the large schools of pelagic hunters are never far away. Whoa, big school of rainbow runners. Oh, they've been brought in by the flasher. You can see where they get their name from. Look, they've got this lovely blue stripe along the side. Whoa, sometimes when you rub your fingers together like this, it draws the predators in because it sounds like a struggling fish. Rainbow runners are true open water predators, hunting in groups to confuse their prey. They can reach speeds of up to 40 miles an hour and could travel thousands of miles in search of food. Whilst the fads are the favoured spots for rainbow runners, as well as for barred filefish and schools of juvenile golden trevallies, in the open ocean, any structure is irresistible. And it's not just the big bamboo structures that things are attracted to in the blue because these ropes are absolutely covered in life. The ropes and streamers that drop down to the ocean floor are covered in algaes, bivalves and sponges. This process is called biofouling and these colonising animals and photosynthesising organisms make use of the ample light and constant supply of drifting food. But they also provide a habitat for an abundance of marine creatures, although to see them, you've got to look pretty closely. This is a species of sea hare, a marine mollusk that grazes on algae. Sea hares are usually found in coastal waters, so finding one attached to a rope drifting in the open ocean is pretty strange. This one was likely pulled off the bottom by strong currents and carried out to sea, although for other sea hares that suffer the same fate, most won't be lucky enough to find a food-covered rope to survive on. Other small critters like juvenile blennies and filefishes also hide close to the ropes, using advanced camouflage to remain undetected. Larger fangtooth blennies are less conspicuous, however, traversing the ropes in search of food. They may look harmless, but fangtooth blennies are so named because they regularly latch onto the mouths and skin of larger fish to parasitically feed. Larger fish like these unicorn leather jackets also hide amongst the streamers that trail behind the anchor ropes. These horned filefish are a true pelagic species, opting for a very different lifestyle to most other filefish species that spend their entire lives close to shore. This pair certainly don't have thalassophobia. Oh, it's so creepy just looking at this rope disappear down into absolute nothingness. I can see a few fish swimming around down there, but I've got absolutely no idea what's at the bottom of it. Now, you might think that most critters wouldn't dream of leaving the safety of these anchor ropes. The open ocean is vast and full of dangers, but some critters seem to love an adventure. Whoa, guys, look, this is a proper pelagic swimming crab. He's just out swimming in the blue. He'll probably come and say hello to me. Oh, there you go. Look, look at that. I'll be nice to him and take him back over to the rope. How cool is that? Oh, no, don't go that way. I'm not entirely sure where he's gone now. Is he out swimming in the blue? Oh, well, I'm sure he made it. Either that or I'll find him when I'm washing my hair this evening. Ow! Oh, look, there's the crab. He's on my fin. No, no, where are you going? No, come here. Oh, ****. Where has it gone? Where is it? Oh. Oh, my word. It shouldn't be on there, mate. Get away from me. Oh, right, where has he gone? No, come on, that's the end of this now. Ouch! So, I've got him. He's being taken back to the rope now, though. No more messing around. I tell you, if this thing swims back at me, I'm not going to be happy. Right, stay there. Whoa, look at this. Oh, that's a massive jellyfish. Oh, and the rainbow runners are feeding on it, it seems. And that's because inside of it, there's loads of small little fish. So, again, this is a great example of figmotaxis, where these small fish are hiding inside this jellyfish because it provides safety. Down it goes, look. Down into the depths. However, whilst this jellyfish was heading back to the deep, as the sun sets every evening, trillions of planktonic species start their journey up towards the surface. And at night, the open ocean is alive with some of the strangest creatures you've probably ever seen. So, every night in this ocean, the biggest migration on planet Earth happens, and it's called the dial vertical migration. And it's where trillions of small plankton come up from the deep ocean to the surface to feed. Now, there's loads of different species that we're looking for, but one of the main ones are these jellyfish right here, characterised by their pulsing lobe and long stinging tentacles. These jellyfish are part of the planktonic community, meaning they're not strong swimmers and instead drift with ocean currents. Their transparent bodies, made up of 95% water, make them nearly invisible to predators as they rise up from the deep. Although, the small fish that seek shelter within some of the jellyfish's bells don't do much for their camouflage. And these jellyfish are covered in stinging nematocysts that line these tentacles. Whilst most close encounters with jellyfish don't result in a painful sting, many different species drift around in these seas, trailing their long tentacles. And if you don't know which ones are the dangerous ones, it's best to keep your distance. The craziest thing about the dial vertical migration is that not only is it the biggest migration on Earth, but it happens every single night. So once these jellyfish and all the other plankton finish up feeding on the surface, they'll head back down into the deep ocean. And I wonder what's all the way down there, several hundred metres down. Oh, that's spooky. But the jellyfishes aren't the only gelatinous creatures that drift around in the darkness. And this thing here is a comb jelly. And unlike the true jellies, these guys don't sting. And you can see it's got these rows of shimmering cilia that it uses to move around. And these aren't actually creating light, but they're refracting the light from my torch. And we're seeing it as this rainbow effect. So for contrast, we've got a regular jellyfish just here, and then a comb jelly here, and you can see it's shimmering. Whoa, what have we got here? This thing is pulsing, so it's possibly a salp. So these salps are gelatinous tunicates, and they're made up of something called tunicid, which is a cellulose-based substance. And this is incredibly unusual for animals. Salps are colonial organisms, more closely related to vertebrates like humans than jellyfish. They feed by filtering organic matter from the ocean, using rhythmic muscle contractions to pump water through their bodies. They use the same muscles for propulsion. Perhaps the weirdest fact about salps is that one of the fastest growing creatures in the animal kingdom, capable of doubling in size in a single day. These planktonic creatures play a really important part in nutrient cycles, including the carbon cycle, by sucking CO2 out of the atmosphere and pooping it in the deep ocean. But it's not just gelatinous creatures that take part in the dial-vertical migration. What is that thing? It's like a strange crustacean. It's like some kind of shrimp. Maybe it's a juvenile mantis shrimp, although I'm not entirely sure. Whoa, there's loads of them, look. Like many crustaceans, mantis shrimps exist as plankton before settling on the ocean floor to hunt. They make use of frilly appendages to swim around, and even at a young age are armed with some of the most complex eyes in the animal kingdom. Like their adult counterparts, many also have needle-sharp spears, so you've got to be a little bit careful they don't run into your fingers. Amongst the hordes of copepods and amphipods, other familiar crustaceans can also be found in the Blackwater. Whoa, what is that? It looks like a juvenile banded coral shrimp. Look at it go, full speed ahead. Oh, that's so strange, the way it tucks its limbs up and swims super quick. Like the mantis shrimps, these banded coral shrimps will also spend their early life in the open ocean, before finding a nice spot on the reef to hide in. There are some things in the Blackwater here that I've got no idea where to even start with. I mean, this thing here looks like a stick, but it's swimming. The sheer diversity of planktonic creatures you can encounter in the open ocean at night is truly remarkable, and given how no planktonic creature controls where they end up, it's possible that anything could emerge out of the darkness. Like these tentacled creatures. Believe it or not, this is actually a planktonic tube anemone, and it floats around in the Blackwater, feeding on the plankton that it catches with its long arms. As adults, they sink to the ocean floor, bury their bodies in the sand, and start building a tube to live in. And all this plankton you can see here, including this larval tube anemone, this is zooplankton, or animal plankton, as opposed to phytoplankton. And phytoplankton is the photosynthesising plankton that lives near the surface. And this is what all of this zooplankton has come up to feed on. You'll be pleased to know that worms also take part in the dial-vertical migration, and it's not uncommon for them to work their way down your wetsuit, or, if you're really unlucky, into your ears. But whilst dodging the fields of worms, stinging jellies, and paralysing siphonophores, I was most excited to try and spot different larval fish species floating around in the darkness. Like this planktonic shrimpfish, that was probably a little too big to still be drifting around so far from the ocean floor. This is another familiar-looking species, a juvenile lionfish that had started to develop a yellow colouration. Perhaps this is the offspring of the yellow shortfin, or dwarf lionfish, that hunt on the shallow reefs in this area. I'm sure this youngster was making the most of his lightning speed and cavernous mouth to gorge on the plankton that was attracted to our lights. And you might have noticed that a lot of the plankton is attracted to torchlight, and that's because they think it's the moon. Although, at the moment, the lights on our boat are acting as a much brighter second moon. But just as we were about to head back to the surface, I spotted a famous blackwater species kicking about in the darkness. Believe it or not, this is a flounder, that, like all flatfishes, has evolved to have both eyes on one side of its body to enable it to lay flat on the ocean floor. In its planktonic form, these flounders swim like normal fish. Although, we also found another species of flatfish that was a little further along in its development, that seemed to be a little bit confused as to what it was supposed to be doing with its body. No matter how many dives I do in the open ocean at night, there will always be something else to discover. Subscribe if you want to see what we find next, and if you loved this video, you'll probably like this one too.