Manatees

Alex Re (00:01): 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 going to come out of here knowing more about your favorite animal than you did before. On this episode, we're talking about a huge herbivore that lives in the water. No, it's not a hippo. These animals are much less dangerous. They also have some seriously cool adaptations that help them survive in their environment, so make sure you apply sunscreen because we're heading to Florida as well as some other places to talk about manatees.

(00:57): Manatees are also known as sea cows, and there could be a few reasons for this, which we'll touch on throughout the episode. One thing they have in common with cows is that they're mammals, which means that they're more closely related to us than they are to fish even though they live in the water. Some of closest relatives are dugongs, which are very similar looking animals and also elephants. They have gray skin just like an elephant does, but they also have a tail shaped like a large paddle. Sometimes parts of their body can appear to be green because algae grows on their backs and in order to reduce the buildup of algae, their skin actually flakes off pretty frequently. Now, they may not be the cutest looking animals, but they're part of the reia family. That name comes from sirens, which are mythological creatures, kind of like mermaids.

(01:52): This is because manatees were probably the beginning of the legend of mermaids. Ancient sailors mistook manatees for women that were half human, half fish. There are three accepted species of manatee, the West Indian, African, and Amazonian manatee. There was a fourth species, which is now extinct, called Stellar's Sea Cow, and their names can give you a hint about where they can be found. You can find them along the southeastern coast of the United States, mainly around Florida, and they can be found off the western coast of Africa and in the Amazon River in South America. Manatees usually like to live in brackish water. This is like a mixture between salt water and fresh water. This type of water is found in estuaries. Some species do live in fresh water like the Amazonian manatee, but you definitely won't find them out in the open ocean. Just like many other marine mammals, manatees are massive in size, they can get up to 13 feet long and weigh over 3000 pounds.

(03:00): That's the weight of about 10 couches combined. They also sleep underwater for about half of their entire day. If you never saw a manatee before, you'd probably think it was kind of like a seal, but they're very different and even though seals are also marine mammals, they're not closely related at all. Manatees are much slower than seals and they also can't go on land. They're fully aquatic. While seals can live on land and in the water at full speed, manatees can move at around 19 miles per hour, which is pretty fast, but they can only maintain the speed for short amounts of time. Seals, on the other hand, can hit speeds at around 30 miles per hour in the water. Now there's a reason manatees didn't have to adapt. Blazing fast speeds. First of all, they don't have many natural predators at all. Their biggest threat is probably crocodiles, but they don't usually go after manatees due to their large size and because of where they live, they don't have to deal with the large predators of the open ocean like orcas or great white sharks. Another reason why manatees move relatively slowly is because of their diet, which is different from almost every other marine mammal out there. You'll hear about that right after the break.

(04:31): The science word that I want to tell you about today is chromatophore. This is a cell that contains a pigment, meaning it's what gives a lot of animals their color. Some animals are able to use chromatophores in order to change color like chameleons or octopuses instead of chromatophores, humans and other mammals have cells called melanocytes.

(05:06): Okay, we're back. Another characteristic that manatees have in common with cows and other close relatives is that their herbivores, meaning that they only eat plants. This is why they're able to move slowly. Their food isn't going to swim away from them. The largest part of their diet is grasses like shoal grasses and turtle grass. There's even a grass named after them called manatee grass and they like to snack on that as well. Aside from grass, they'll also eat mangrove leaves and algae. They're thought to eat almost 10% of their body weight every day. Now, even though they're mainly herbivores, they have been known to eat the occasional fish or clam manatees mouths are extremely well adapted to what they eat. All of their teeth are molars made for grinding up plants just like a cow's teeth, but they have a unique problem when it comes to eating sand.

(06:04): Now, if you've ever had sand in your food at the beach, you know it's not easy to bite down on. Well, because their food is located at the bottom of brackish waters, sand becomes a big problem. It gets in their food and wears down their teeth quickly to resolve this issue. Manatee teeth are constantly falling out and being replaced by new teeth. Manatees also have prehensile lips, meaning that they can use them to grab onto things. They use their upper lip just like an elephant would use its trunk. They grab grass with their lip and then bring it to their mouth. This comes in handy when you have flippers instead of hands. Their flippers are useful though. They help manatees steer while swimming, and they also use them to walk on the floor of estuaries while they're feeding. You'll probably see them swimming in more shallow waters because sunlight needs to be able to reach the bottom so that these brasses can grow Because they're mammals, manatees don't have gills and still need to hold their breath underwater.

(07:09): They can hold their breath for about 20 minutes before needing to come back to the surface. This is another reason why moving slowly is actually helpful for manatees. They're expending very little energy when they swim, which means they expend less oxygen so that they can hold their breath longer in order to use even less energy when they know they need to dive for longer periods of time. Manatees are able to slow their heart rate down from 60 beats per minute to 30 beats per minute, and they float in the water with their back towards the surface and their belly towards the ground. This means that their mouth is facing downward, so in order to breathe through their mouths, they would have to roll themselves over. Luckily for them, they don't need to do this, especially because they only have six neck vertebrae while pretty much all other mammals have seven.

(08:04): Because of this, they aren't able to turn their necks. They don't have blow holes like whales, but they use their two nostrils for the same purpose. Their nostrils face upwards towards the surface and they mainly use them to breathe. Their nostrils are also really cool because they can close to be watertight when they dive. Manatees eyes are also really well adapted to life in the water. They don't have eyelids, but they do have a structure called a tating membrane. It's like a clear cover that can go over the eye so that it doesn't get damaged, but also still allows them to see underwater, kind of like a pair of built-in goggles and manatees also have really good eyesight. They can see around 10 meters in the distance while they're underwater. Using your eyes in the water isn't always reliable though because it could be dark or murky. That's why they also rely on their sense of touch. The genus name of all manatees species is trite. This comes from the Greek word trico, which means hair manatees have hairs on their face that look like a beard. The hairs give manatees the ability to feel around in their environment. Smaller hairs can also be found all over their bodies and they can help manatees detect changes in water pressure and water currents. They also have a really good sense of hearing and are known to make all kinds of sounds under the water.

(09:43): They usually make these sounds when they're interacting with other individuals. Sometimes even for mating purposes. Manatees have a slow reproductive cycle. They mature at around five years old and females have offspring around every three years. During the mating season, a female manatee is followed around by a group of males that all want to mate with her. The females are pregnant for about a year and the babies are reliant on their mothers for about two years feeding off of their milk. Meanwhile, the father has no part in caring for the offspring. An hour after being born, the baby is already able to swim by itself, which is pretty amazing, and manatees have been known to live for about 40 years. They also tell an interesting story about evolution. Their ancestors, along with all other marine mammals at one point lived on land and they still have remnants of what used to be. For example, all except the Amazon species still have toenails on their flippers. This is because their land living ancestors used to have claws. A structure that was passed down from ancestors that no longer has a use is called a vestigial structure. An example of this in humans is our appendix. Unfortunately, manatee populations aren't doing great right now, and we'll talk about why right after the break

(11:24): Time for today's trivia question, what is the percent chance of you ever being attacked by a shark? The answer is .000026%, which is about one in 3 billion, so sharks are not really something to worry about at the beach.

(12:02): Manatees are extremely important to the ecosystems that they live in. They eat a lot of sea grass, and by keeping the grasses short, they're actually improving the health of these plants. This keeps the entire ecosystem thriving because it helps animals that rely on the grasses, which then helps animals that rely on those animals. There's also evidence to suggest that manatees are very intelligent. They've been known to have a good long-term memory. They migrate long distances year after year, usually returning to the same spot they were before, and manatees that are in captivity have also been able to follow commands from their trainers. As I mentioned earlier, manatee populations are really struggling right now. They're marked as endangered by the I U C N red list, and there are only about 13,000 total manatees in the wild today. One of their biggest threats is actually boats because they swim in shallow waters so close to the surface, they often get hit by the propellers on the back of boats.

(13:09): In 2021, around 1000 manatee deaths were reported of the deaths caused by humans. 90% of them were caused by boats. Another large issue for manatees is a lack of food. Their food is dying off because of algal blooms in the water. This is basically when too much algae starts growing in the water, which kills off other plants and animals. Algal blooms are caused by an excess amount of nutrients in the water, which is usually due to the overuse of fertilizers by us. The manatees are starving because all of their food is disappearing. Lastly, temperature changes also cause a significant amount of harm to manatees because more and more developments are being built near manatee habitats. They have less access to natural hot springs. They use these hot springs to keep themselves warm because if the water gets too cold for them, they'll die. Instead, they've been resorting to gathering around power plants, which heat up the water around them.

(14:17): This isn't safe or healthy for the manatees and they could also be in big trouble because of it. Luckily, there are some organizations that are working to help manatee populations. You should take a look at Ecology Save the Manatee Club and the Florida Fish and Wildlife Conservation Commission. Thank you so much for coming on this adventure with me. As we explore the world of manatees, you can find the sources that we use for this podcast and links to organizations that we reference at onwildlife.org. You can also email us with any questions at On Wildlife.podcast@gmail.com, and you can follow us on Instagram at On Wildlife or on TikTok at Wildlife. Don't forget to tune in next month for another awesome episode, and that's On Wildlife

Jess Avellino (15:16): You've been listening to On Wildlife with Alex Re. On Wildlife provides general educational information on various topics as a public service, which should not be construed as professional financial, real estate, tax, or legal advice. These are our personal opinions only. Please refer to our full disclaimer policy on our website for full details.