Piranhas

Alex Re

Hello, welcome to on wildlife. I'm your host, Alex Re. On this podcast, we bring the wild to you, we take you on a journey into the life of a different animal every week. And I guarantee you, you're gonna come out of here knowing more about your favorite animal than you did before. The animal that I'm going to be talking about for this episode has been labeled as vicious, ruthless and dangerous. They can even be found in countless forms of media, which depict them as something from a horror story. And today, we're gonna find out if it's all true. So grab your fishing poles, because we're heading into the rivers and lakes of South America to talk about Puranas.

Around 60 different species of Parana and all of them are found in South America. They live in rivers and streams, and probably the most common place to find them is in the Amazon River. And they prefer areas where the water is murky, or there's a lot of vegetation because it provides good protection from predators. These fish are known for having extremely sharp teeth, but they're a little misunderstood, and we'll talk about that later in the podcast. Some of the larger species of Parana can get up to two feet long, but it's not their size that strikes fear into people, but the fact that they live in groups called shoals. In some species, they can have over 30 individuals in a shoal. They also have a flat body and are usually pretty colorful. For example, one of the most commonly known species of Parana is the red bellied Parana, which is bright red on its underside. And scientists believe that Puranas have been around for over 25 million years, which falls into what's called the Miocene epic. And the Miocene epic saw some pretty cool animals emerge, such as the saber tooth tiger, and the first species of bears. As I mentioned before, Puranas have a reputation of being vicious hunters that will eat anything in their path. But this is a common myth. Some species are carnivores, eating fish, worms and insects. And one thing's for sure, they definitely don't go out of their way looking for humans to eat. And they usually need to eat about 1/8 of their body weight every day. species such as the black banded Parana don't eat the whole fish, they eat their fins and scales. This is because they grow back and they're much easier to digest than bones. But other species are actually herbivores, so they would much rather eat plants than any type of meat. Nevertheless, they do have really sharp, deep and powerful jaws that help them rip apart their food. Their bite force is insane. They can bite with the power of over 70 pounds, which is the most powerful fish bite compared to its body size. One species of fish called the Arab ima lives in areas with Puranas and is actually evolved to have scales that are impenetrable to Parana teeth, and the teeth of Puranas are actually interlocking. So when they lose teeth, it doesn't happen one at a time, they lose an entire row of teeth on one side of their mouth. But luckily, the new set of teeth has usually already grown in waiting for the old ones to fall out so that they're never without a set of teeth. So Puranas are the automatic thought when killer fish come to mind. But are they really as dangerous as they seem? Not at all. If you swim in waters that are filled with Puranas chances are that they won't even want to come near you were most likely thought of as a huge predator in their eyes, not food. In fact, there are around 200 incidents of Parana attacks every year. And if you could see me I would be putting air quotes around the word attack, because they mostly involve someone's toe or foot getting bitten. And of those 200 attacks, a very small amount result in deaths because Puranas just don't go after humans. You have more than double the likelihood of falling out of your bed and dying then of ever getting bitten by a Parana they're still dangerous, so you don't want to go poking around in their habitat, but not as dangerous as you've been led to believe. And one of the reasons that people think of Puranas as these vicious creatures is because of Teddy Roosevelt. When he went on a hunting trip to Brazil, he saw a feeding frenzy of Puranas. But it was all planned, local starved a group of neurons for a long period of time, and then through a cow into the water which made the Puranas devour the cow. After seeing this, he wrote about how dangerous they were in one of his books. He called them the most ferocious fish in the world. Okay, we're gonna take our first break. And when we get back, I'm going to start talking about Parana behaviors the person that I want to recognize in this week's episode of notable figures in science is Dr. Rosalind Franklin, a chemist who was trying to figure out the structure of DNA in the 1940s. She was able to take extremely clear pictures showing that DNA was a double helix. But her two male co workers, Watson and Crick, took these images and use them to create their own model of the structure of DNA. At this time, they got all the credit for figuring out its structure, and they even won a Nobel Prize because of it. Franklin also did important work into the structure of different viruses. Although she passed away and only 37 years old, she's finally getting the recognition that she deserves for making such a groundbreaking discovery. If you want to learn more about Rosalind Franklin, or this series, you can check out on wildlife.org.

Okay, we're back. So we just finished talking about the Parana diet. And one of the most common ideas about Puranas is how they participate in feeding frenzies, which are basically really aggressive group attacks on their prey. You may think that they swim around in groups so that they can hunt their prey together. But this actually isn't the case. While some species of Puranas participate in feeding frenzies. Most Puranas stay in groups for different reason. Puranas are definitely not the top of the food chain where they live. Common animals that eat them are Caymans, and otters, so they stay in large groups as protection from predators, you have a much smaller chance of being eaten if you're in a large group. One study found that when Puranas were in larger groups, and were faced with a predator, they had a much lower response, meaning that they were less likely to flee than in smaller groups. So Puranas in small groups were a lot more on edge than in the larger groups. There are a lot of benefits of being in a larger group as well, like how Puranas in large groups may use up less oxygen, because they're not constantly on edge. Even though fish live underwater, they still need oxygen just like us. We get it from breathing through our lungs, while fish use their gills to take in oxygen through the water. The amount of available oxygen may not seem like a problem for those of us who breathe through the air. But in some bodies of water, especially where Puranas like to live, oxygen levels can be extremely low. So that being said, a lower oxygen intake could be the difference between life and death. Puranas have also been found to have different personalities based on their life stage, and their position within the shoal can be an indicator of their personality. For example, the younger fish are a little bit more adventurous, so they usually stay towards the outer part of the show, while older individuals like to stay towards the middle of the show, because they don't like to take as many risks. Because Puranas are both predator and prey species, they need to have acute senses to detect other organisms in the water. First is their sense of smell. Because some Puranas are carnivores, they can use this strong sense of smell in order to find a bleeding animal, they can smell one drop of blood in over 50 gallons of water. They also have really large eyes, which gives them pretty good eyesight, they can see in color, and they actually don't have any eyelids, so they can't blink. But they do have a really important layer in their eye. That helps reflect light so that they can see in murky water. Hearing may not be something that you think about when you're underwater. But Puranas have a really good sense of hearing too. They mainly use hearing as a way to sense predators, but it could be used to sense its next meal. For example, they can hear splashing water as a sign of either an animal that's drowning, or fruit that's falling from a tree into the water. And not many people know this. But Puranas can actually bark like a dog. They use these vocalizations to warn other members in the group that there may be a predator, or to scare away another animal coming into its living area. But by far, the coolest sense that they have is their motion sensing. They have this structure called a lateral line that runs across the middle of their body. And it can pick up on vibrations that are made by other organisms in the water. Pretty cool stuff. Okay, we're going to take our last break. And when we get back, I'm going to talk about why Puranas are important to their ecosystems. It's trivia time. What element makes up most of the Earth's atmosphere? A oxygen, B nitrogen, C helium, or D hydrogen? The answer is B. Almost 80% of our atmosphere is made up of nitrogen. Even though it's really important for us to survive, we can't breathe it in. We get it from eating plants and animals.

Okay, we're back. Let's talk about why we should care about Puranas. though they're one of the most feared fish in the world, they're actually critical to the ecosystems that they live in. First of all, they're a food source for larger predators that live in or near the rivers that they swim in, like Caymans, otters, Amazon river dolphins, and other species of fish. This is especially important in the areas where they live like rain forests, because a large amount of those animals are on the decline due to deforestation and climate change. They also help control other populations of fish from getting too numerous in the river by eating them. Some products are also scavengers, which means that they could play a part in cleaning up dead and decaying organisms in the bodies of water where they live. Unfortunately, many fish are declining in these areas, but Parana populations are staying the same or even increasing. But why are these fish populations declining? This is due to a few reasons but mainly overfishing. Many fish in the South American rivers and lakes are fished unsustainably, which means that they aren't given enough time to recover their populations before they're getting taken out of the water again. Another issue that you may not think could have an impact on bodies of water is forest fires. The Amazon rain forest is currently facing some serious forest fire issues, which is affecting areas like flood plains. The flood plains are forested areas that get flooded with water from rivers at certain times of the year. And they're the home to 1000s of different species including Puranas. When the trees in the floodplains burned down, that destroys a lot of the food that the fish need to survive, and can also wipe out their shelter. But this doesn't explain why Puranas aren't decreasing. Well, it has to do with the fact that many of their predators are dying out. otters, river dolphins and other large fish that prey on Puranas are all seeing a decrease in their populations, meaning more Puranas are able to thrive. This could be throwing off the balance of the ecosystem, because Puranas need to eat a lot of food. And if they go unregulated, they can wipe out all the other fish in the ecosystem. Puranas are also popular pets for a lot of people. But the problem is that they need a lot of room, so a normal fish tank isn't sufficient enough for them to live in. This becomes a major problem for pet owners, especially as the fish starts to grow. If they become too big, the owners will oftentimes release the Puranas into bodies of water near them, which is extremely dangerous. First of all, the Parana will most likely die because the conditions of that habitat will probably not resemble the type of habitat that they need. Second, if they do survive, it can cause them to become an invasive species. This could eliminate other organisms from their own habitat. Because Puranas need to take in a lot of food. We see a good amount of invasive species popping up in America, some of which are due to irresponsible pet owners. For instance, the Burmese python, which is indigenous to the forests of Asia, is currently an invasive species in Florida. They're causing problems for a lot of different species, especially alligators, because they eat their eggs and a lot of the animals that the alligators would normally eat. So Puranas are important, but they belong in their natural habitat, not in some pond in Florida, which could have some serious consequences if we're not careful. Many fish that live in the same ecosystems as Puranas are facing declines in their populations. But fortunately, there are some great organizations that are working to help them right now. For example, there's Amazon watch, international rivers, and the forest foundation us. Thank you so much for coming on this adventure with me as we explored the world of Puranas. You can find the sources that we used for this podcast and links to organizations that we referenced at on wildlife.org. You can also email us at on wildlife dot podcast@gmail.com Don't forget to tune in next Wednesday for another awesome episode. And that's on wildlife.

Jess Avellino

You've been listening to on wildlife with Alex re brought to you every Wednesday.

Transcribed by https://otter.ai