Bottlenose Dolphins

Alex Re (00:00): 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. This week we'll be discussing one of the smartest animals in the world. They're also one of the most beloved animals in the ocean, and it's easy to see why that is. When you go to the beach, you might see their fins popping up out of the water, so make sure you bring your binoculars because we're going to be talking about bottle nose dolphins.

(00:53): There are around 40 dolphin species, but today we're talking about the bottle nose dolphin, which is probably the species that most people are thinking of. Some people have recognized two types of bottle nose dolphins, onshore and offshore, where the offshore dolphin is typically larger and darker bottle noses. Dolphins can be found in oceans all over the world, but they usually like to live in warmer waters in the summers. They're most commonly found in the Chesapeake Bay and the Atlantic Coast. Their scientific name is TSI Ops Tatas, and they're called bottlenose dolphins due to their short bottle like snouts. The term dolphin comes from the ancient Greek word delphis, which means womb, and this is because even though dolphins live in the ocean, they're mammals, so the embryo grows inside of the mother's womb instead of an egg being laid. Some of the dolphins closest relatives include whales, porpoises, and hippopotamuses, and they're not closely related to sharks or other types of fish at all.

(01:57): All bottle noses. Dolphins are a sleek gray color with a light white or pink underbelly, and their skin is extremely smooth. It almost feels like a wet rubber mat. They need to keep their skin smooth because it increases their swimming speed and efficiency by reducing water resistance. Olympic swimmers shave their body hair in order to do the same thing, but the way dolphins keep their skin nice and smooth is by shedding their outer skin layer every two hours and it pays off because they can swim at speeds of over 20 miles per hour. If you look closely at their skin, you'll also see that they have ridges all around their body. These are called cutaneous ridges. They're thought to be another way to increase their swimming efficiency, but the other features that really help them swim through the water with ease are their fins. They have a curved dorsal fin on their back, which really helps to cut through the water and increase the dolphin's hydrodynamics.

(02:56): Their dorsal fin doesn't have any bone or cartilage helping to hold it up. Instead, it's made of connective tissue that's densely packed together, and they also have two flippers, one on each side of their body that helps them to control their movement. Bottle nose dolphins usually grow to be around 10 to 14 feet long and they can weigh over 1400 pounds. That's eight times the weight of the average human. Because they don't have gills and need to breathe air, they have a blowhole located on the top of their head. They can hold their breath underwater for about 12 minutes. This is the reason that you'll see dolphins frequently popping their heads out of the water when they swim, and something that makes them unique from other dolphin species is that they evolved to have five of their seven vertebrae unfused, which gives them more flexibility and neck movement than other dolphins. This helps them move, swim and hunt better, and the average lifespan of a bottle nosed dolphin is about 45 to 50 years. Let's take our first break, but hang on because we've got a lot more cool stuff to talk about. The science word that I want to talk to you about today is apoptosis. This word refers to when cells self-destruct on purpose. Sometimes this happens when your d n a is damaged in order to protect you. The cell that has the D n A that's damaged will self-destruct. It also happens when we're developing. We develop with webbing in between our fingers, but apoptosis occurs before we're born that destroys the cells that make up that webbing. Pretty amazing.

(04:55): Okay, welcome back. Bottle nose dolphins are carnivores and they're near the top of the food chain. Their diet consists of fish, squid, shrimp, and small crustaceans, but it really varies depending on where they live. They consume around 15 pounds of food every day, and they have between 86 and a hundred cone shaped sharp teeth which are able to hold onto slippery fish. They have a lot of really amazing hunting strategies to help them catch their prey. Some dolphins will use their tails to make a mud ring around a school of fish to decrease their visibility. The fish then get scared so they leap out of the water, but the dolphins are waiting for them with their heads out of the water and their mouths open, ready to catch them. Some dolphins search on the sea floor using echo location to find prey that's hiding underneath the sand.

(05:48): We've talked about echolocation a few times on the podcast, but basically how it works is the dolphins send out high frequency sounds through the water. Those sound waves bounce off of an object that they're aiming at and then bounce back at the dolphin. This gives them an image of their surroundings without even having to see. They've also learned that following boats is a good strategy because fishing boats can offer lots of free fish, but bottle nose dolphins also have one of the coolest hunting strategies in the animal kingdom. These dolphins will force the fish that they're hunting towards the shore. Then they'll swim quickly towards the shore and beach their prey and themselves. They're basically lying down out of the water eating the fish that they beached. Then they'll be pulled back into the water by the waves and then do this again until they're full.

(06:37): It's pretty amazing and it just shows how smart they are. These hunting strategies aren't innate. They have to be taught by other members in their pod and adult bottle. Nose dolphins don't have any known predators, but many dolphins have been targeted by humans over the years. This is something that we'll talk about later on as well. Some juvenile dolphins may be preyed upon by killer whales or sharks, but they're not exclusively targeted by them. As you've probably noticed by now, dolphins are able to problem solve and cooperate just like us. A bottle nose, dolphin's brain is over a pound heavier than a human brain, which means it's about 23% larger, but there are some differences between how our brains are built. For example, dolphins have a very underdeveloped prefrontal cortex while humans have one that's highly developed, this is the part of the brain that impacts our attention and also how we remember tasks that we plan out in the future, but dolphins have a larger cerebral cortex than us.

(07:40): It's about 40% larger than a human's. This is the part of the brain that influences motor function, touch sensation, and processing sensory information, meaning that dolphins have heightened senses of touch, sight and movement compared to humans. Humans also have a larger hippocampus and prefrontal cortex, and overall they just have a larger brain compared to their body size. But because dolphins have just a larger brain overall, they have an increased amount of folds and ridges in their brain, and it's generally thought that a higher amount of folds means a higher amount of intelligence. Dolphins are also one of only a few other animals on the planet that can recognize the reflections in mirrors besides us. Bottle nose dolphins reach maturity at different ages depending on their sex. Males mature at around 10 years old and females reach maturity between five and 10 years old. Females are known to give birth every three to six years and have a gestation period of an entire year.

(08:42): Dolphins reproduce through internal fertilization just like humans and female dolphins give live birth underwater from the moment they're born, juvenile dolphins are able to swim. They're also, which means that they have multiple mating partners, almost always with other members of their pod. Most dolphins mate in the spring, but they don't have a specified mating. A juvenile dolphin is called a calf, and calves are dependent on their mother's milk. For the first two years of their life, juvenile dolphins will stay with their mother and learn to hunt and live for the first three to six years of their life. Okay, let's take our last break, and when we get back, you'll hear more about how dolphins interact with each other. Time for today's trivia question, how fast do house flies flap their wings? House flies flap their wings 190 times per second.

(10:08): Okay, welcome back. A group of bottle nosed dolphins is called a pod. Dolphin pod numbers can vary greatly depending on where they live, but they don't have to be in a pod to survive like other social animals and are one of the few species that can live both solitarily and socially. And just like us, dolphins can have friendships, their friendships last decades where they hunt, forage and protect each other. Many scientists think that one of the best indicators that they're extremely intelligent is the close bonds that they form with other individuals. Social groups. For offshore bottle nosed dolphins are much larger than onshore dolphins, which makes sense because there's a lot more space out in the open ocean. Groups of offshore dolphins can reach hundreds in number while onshore usually range between five and 20 individuals in order to communicate with each other, dolphins use sound.

(11:04): They use a series of clicks and they pretty much have their own language. They make distinctive sounds when addressing other individuals, and this is actually them calling each other by names, but dolphins don't have vocal cords, so how do they make sound? The noises are made through airflow in their nasal passages, which are located underneath their blowhole, and they're able to pick up the sound because they have a really good sense of hearing. Sound travels through the dolphin's, lower jaw to its inner ear, and then it's transmitted to the brain. Some scientists think that if we ever want to communicate with another animal, our best chance to do that is with dolphins because of their complex communication system and their intelligence. Bottle nose dolphins play a key role in the food web of the ocean where they eat many different kinds of fish and other sea creatures that could overpopulate.

(11:57): In particular, the number of squid are on the rise due to the fact that most fish populations are decreasing with the absence of dolphins, the natural balance of the food web would be even more unbalanced, which could negatively affect the health of the ocean environment. While bottle noses, dolphins are not endangered, their populations are decreasing, and their biggest threat is humans. If you've been to aquariums and amusement parks, you may see bottle noses dolphins in captivity. This is particularly cruel because dolphins need a lot of space, mental stimulation and strong relationships with other dolphins to thrive, and for the most part, they're not getting this in captivity. That's why you can see behaviors that show that they're stressed and unhealthy. Some of those behaviors include banging their heads against walls and a loss of appetite. Humans have also hunted bottlenose dolphins for hundreds of years, and there are whole ceremonies centered around these hunts.

(12:56): In certain parts of the world, the most practiced strategy is called drive hunting, where people will use boats to force the dolphins to shore and lead them to be killed. But luckily, because of their high intelligence, many governments protect dolphins legally and conservation. Many countries have classified dolphins as non-human persons, which give them legally enforceable rights to life. Even though these laws are in place in many areas around the world, it's still really important to fight for their conservation and their freedom from captivity. If you want to help bottle nose dolphins, you should check out Rick o' Barry's Dolphin Project, Whalen Dolphin Conservation U Ss A and the Bottle Noses Dolphin Research Institute. Thank you so much for coming on this adventure with me as we explored the world of Bottle Nose Dolphins, 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 could follow us on Instagram at On Wildlife and on TikTok at Wildlife. Don't forget to tune in next Wednesday for another awesome episode, and that's on Wildlife

Jess Avellino (14:21): You Can 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.