Watch this 2-meter deep-sea fish feed 100+ babies with its own body

As the biggest river in the world, the Amazon is renowned for its unique wildlife. There's the infamously carnivorous piranha, the elusive pink dolphin and blind electric eels. But perhaps stranger than almost any other fish is the Ara Pyma, the largest freshwater fish in the world. They generally grow to be 3 meters long and weigh up to 200 kilograms. For comparison, that's how big Bottlenose Dolphins usually get, and the size of the arapima is hardly the most unusual thing about them. The closer you look, the weirder they get. From Bony tongues to ceramic scales, they've proven themselves to be among the fittest of survivors. And if you were to observe them shortly after their eggs hatch and their offspring start swimming, you would see something that appears to break the rules of biology, Adult Arapima feeding their young with their own milk. But scientists have struggled to understand the strange adaptations and behavior of the Arapima because the fish have become increasingly endangered due to overfishing. Luckily, protecting the Arapima might also lead to greater protections for the Amazon rainforest as well, making them not only a worthy subject of research, but potentially the lynchpin for the conservation of the entire ecosystem. The earliest ancestors of the Arapima were the first members of the Osteoglossomorpha Super Order, who appeared about 100 and 87,000,000 years ago in the Early Jurassic. The name of this group literally means Bony tongues, indicating that unique adaptation. At this point, the fish weren't Amazon dwellers since the river didn't start forming until 11:00 million years ago. Around 23,000,000 years ago, the Arapima assumed the form that it has today, making it among the oldest living freshwater fish on the planet. And by this point, it had a number of adaptations that made it perfectly suited for the low oxygen freshwater river. Unlike most fish, Arapima get 90% of their oxygen needs from the air. Instead of the water, they have a modified swim bladder, which functions almost like lungs, allowing them to suck oxygen from above the water. They can even survive out of the water for up to 24 hours. To understand just how remarkable this organ is in Erapima, it's worth diving a little deeper into swim bladders more generally. For most fish, the swim bladder is filled with air to help them maintain buoyancy at different depths. Some fish have swim bladders, which are connected to their gastrointestinal system. In this kind of fish, like goldfish and carp, they gulp air to inflate the swim bladder, then burp air to deflate it. In other types of fish, swim bladders aren't connected to the digestive tract. They empty and fill their swim bladders by diffusing gas from their blood. For these fish, the swim bladders have nothing to do with breathing. They're more like flotation devices. These fish have gills that filter oxygen from the water and then pass it into the bloodstream. Arapima, on the other hand, have a very large swim bladder that essentially runs the length of their bellies. The organ is characterized by small wrinkles, which increases the surface area to allow for better absorption of oxygen. And when scientists studied the tissue that lines the Arapima swim bladder, they found it was very similar to the tissue seen in the gills of fish that don't breathe air. This swim bladder isn't a true lung like you'd see in a mammal, but it serves a very similar purpose. Despite having gills, Arapima drown within 10 to 15 minutes if they stay completely underwater. This might seem like a weird adaptation for a fish considering they live in the water, but it's actually a good survival strategy if you live in branches of a river like the Amazon that regularly floods its banks. When the river infiltrates the forest during the annual wet season, the water is filled with decaying vegetation. This creates highly anaerobic conditions, in other words, a very low oxygen content. This would be a big problem for most fish, but it doesn't bother the Aeropima. In fact, being able to breathe air in low oxygen environments actually gives them a competitive advantage in hunting. While other fish are moving more slowly to deal with less oxygen in the water, the Arapyma can still shoot forward at full speed to capture prey. Arapyma are a formidable predator in the waters of the Amazon. They trap prey by opening their mouths in a way that creates suction, sucking fish, crabs, and even birds and small mammals into their jaws. From there, the prey is crushed between their Bony tongues, sharp upper palate and teeth. Not the best way to go in the Amazon. Few animals sit higher on the food chain. The only predators of these giant creatures are Jaguars, Amazonian alligators, and as you would guess, human beings. And even though Arapima regularly swim in piranha infested waters, they have an amazing adaptation that protects them from being attacked by schools of these dangerous fish. Incredibly tough scales. Erapima skin makes up 10% of their body weight and is surprisingly useful for human products called leather. The incredibly durable material is used for clothing, purses and boots, and their scales are truly a marvel of natural engineering. Made up of 2 layers, the scales are both flexible and tough, meaning the fish can move without any trouble, but are also very well protected from puncture wounds. The top layer of the scales are actually mineralized, making it almost like a flexible ceramic. It's similar to our bones, but all of the hard material is collected at the surface and the lower level is collagen fibrils, which grow in the pattern of a spiral staircase. This structure means that even if the hard outer layer is punctured, the collagen will break at different angles and preserve the overall integrity. It might be deformed, but it won't shatter like a window. Scientists are studying the Aeropyma scales to see if they can use it to improve bulletproof armor, which works similarly by combining soft padding with a hard plastic. But the problem is that this type of armor requires a 3rd material, a sealant, to bind the 2 layers together. In Aeropyma, the binding happens on a molecular level. The 2 layers of the scale simply grow together, which has proven difficult to replicate in the lab. And on top of all of these impressive adaptations, there's one that's so strange it has perplexed both locals and scientists for years. Something that seems like it shouldn't come from a fish at all. When you think of the animals that care for their young, you probably think of animals like us, the primates, elephants, dogs or cats. In fact, all mammals care for their young because all mammals, by definition, provide milk for their babies, sometimes for months and months. Most fish in the world, by contrast, simply lay their eggs somewhere safe and then bounce. But for generations, indigenous people of the Amazon have observed something baffling. Aeropima producing what looks like milk and their babies swimming through it. The creamy white fluid comes out of cavities in the skull of both male and female Arapima during the reproductive. For a long time, people thought this was some kind of nursing strategy, but in 2017, researchers analyzed the chemical compounds of the milk and were surprised by what they found. Instead of being full of protein like milk would be, the cephalic fluid was a mixture of hormones and chemicals that are related to immunological processes. In other words, the milk wasn't nourishing the young, but it was clearly doing something because there was an increase in its production for both males and females when they were having offspring and the young fish seemed to be absorbing it. One of the hormones they found is called prolactin. This was perplexing. Prolactin is the hormone that mainly stimulates breast growth and production of milk in mammals, but the Arapima milk isn't really milk like ours is. Here, prolactin must be serving a different purpose. In mammals and birds. Prolactin is also known to enter the brain to affect neuronal function, inducing parental behavior. In one study, rodents were found to retrieve and groom their pups more often with more prolactin in their system. In birds, prolactin increases parental behavior like nesting, incubation, and feeding. Researchers think that in fish, prolactin could be increasing parental behavior, just as it does in the other vertebrates. And the Arapima are indeed caring parents. Not only do the parents build a nest to hold the eggs and then guard it from predators, the males also help the little fish for up to 3 months after they hatch, the male 's head turn a darker colour, perhaps to offer camouflage to their young, and they sometimes bring the fry into their mouths to move them to another location if predators get too close. Scientists also think the Arapima milk could work as a chemo attractant, keeping the offspring close to the head of the male, keeping them safer and causing them to follow as he searches for plankton rich water that they can feed in. Overall, Arapima babies who are exposed to the Arapima milk grow bigger and are more likely to survive compared to ones who are raised without the milk. But unfortunately, there's still a lot researchers are struggling to understand about the behavior and life cycle of this giant fish. And that's partially because in some parts of the Amazon, Arapima came very close to extinction. For millions of years, Arapima used their many adaptations to rule the Amazon River. But with the arrival of more and more humans, we eventually became their main hunters. And even though the giant fish are well adapted to withstand predation from almost any other creature, their need to rise to the surface for air makes them very appealing targets for humans with sharp sticks. For centuries, local indigenous people relied on arapima for sustenance without causing any strong negative impact to the populations. But the combination of outsiders coming in to catch the fish and locals catching an increasing number of Arapima to sell commercially, the populations around Brazil and Guyana plummeted. But there's strong evidence that protecting the fish and creating restrictions for when the fish can be harvested can be very effective in helping the Arapima populations rebound in communities in Brazil, protective measures like catch limits and a total fishing ban at certain times of the year allowed the populations to grow over 400% in 8 years. Lakes that had only 20 Arapima left ended up with more than 2000. But of course, Arapima live across a wide geographical range and conditions are different from one place to another. In some places, mining and deforestation are a big threat. In others, the commercial overharvesting of the Arapima is the main problem. Different communities respond with different solutions based on their needs. Take Riwa village in Gayana, for example. The Arapima were traditionally an important source of nutrition for the local indigenous people, but overfishing led to a huge decrease in their population. With help from scientists who established surveys to monitor the range and population size of the Arapima, the village was able to create regulations to protect the fish in their area. They also built an eco lodge and started a fishing business that offered catch and release programs to anglers visiting the region for tourism. Not only does this program prevent Arapima from being killed, it also provides income for the villagers who previously relied on over harvesting the fish for their income. And the scientists who work in Guyana have suggested taking Arapima conservation one step further. Because Arapima use the floodplains as part of their habitat, there's a strong need to protect the forests as well as the river. When it comes to policy makers deciding what parts of the forest to protect, ensuring the survival of Arapima requires extending protections beyond the dry season banks of the Amazon. And this kind of protection could help a number of other species who make their homes in the forests as well as the river. There's still a lot we don't know about the Arapima, but with any luck, helping protect the means, they'll continue to rain as the giants of the Amazon and give us plenty of chances to learn more about them. The Era Pyma and all of its strangeness is a product of its wild and unpredictable habitat. The extreme seasonal flooding of the Amazon has shaped its evolution for millions of years. It's a phenomenon that turns the forest floor into the riverbed, huge stretches of land underwater for 6 months of the year. These floods create thousands of river islands in an archipelago that stretches for thousands of kilometers. The largest collection of river islands in the world, the Aeropima, is not the only creature who has been forged from these watery circumstances. These river islands are home to some of the most unusual creatures. Everything living there during the floods is forced to adapt or die. Thanks for watching.