Have you ever seen Flipper? Maybe you’ve watched Dolphin Tale, a movie all about a dolphin (Winter) who loses her tail in a rope and is fitted with a prosthetic one. These movies and television shows are based on one of the smartest marine mammals on Earth, the dolphin.
Dolphins are some of the most fascinating marine animals, and many scientists have been studying them for years. There is still so much to learn about these creatures.
All About Dolphins
Many people believe the ancestors of dolphins lived with the dinosaurs or during the Jurassic Period, but this was not the case. The first aquatic ancestors of dolphins and whales did not live with the dinosaurs. Their ancestors first appeared in the Mesozoic Period. They were oceanic vertebrates and they were marine reptiles, not mammals.
Marine mammals in the cetacean family include whales, dolphins, and porpoises. This means that whales are actually related to dolphins! There are 49 dolphin and porpoise species. These species are divided into six families.
The oceanic dolphin family, which includes bottlenosed dolphins, is the largest, with 38 different members. The porpoise family has seven members and the river dolphin has four families.
Dolphins are one intelligent marine mammal specie and they have very complex and large brains which have been developing for thousands of years. There are 40 different species of dolphins. One of the most commonly known species of dolphin is the Tursiops truncatus or the common bottlenose dolphin. These are the species of dolphins featured in movies and often seen swimming in the ocean.
You will be able to find dolphins in all of the worlds oceans and seas. Some of them even live in rivers. Most dolphins live in open oceans and coastal areas. Coastal waters include bays, inlets, rivers, gulfs, and channels. These may even be shallow water.
Most dolphins live in saltwater. Others, like the River Dolphin, live in freshwater! Dolphins prefer tropical or warm climate waters like the Mediterranean Sea. You will also be able to find them in temperate waters too. You will even find orcas (often known as killer whales) in cold waters like the Arctic and Antarctic waters. The water temperature usually does not bother dolphins!
Dolphins will often swim toward the water’s surface because they need to be able to breathe. They often get confused with sharks because of their dorsal fin or the fin on the top of their backs will stick out of the water when coming up to breathe.
Dolphin’s skin is smooth and rubbery. It usually is black, white, and dark gray. They have two fins on their sides and a triangular fin called a dorsal fin. Dolphins have blowholes on the top of their heads, and they use their blowholes for breathing. They also have a layer of blubber or fat. Dolphins do not have jaw muscles, so they do not use their top or lower jaw to chew their food.
With the species of bottlenose dolphins, male bottlenose dolphins are slightly larger than female bottlenose dolphins. Dolphins usually are 8.2ft to 11.5 ft. Some may be smaller or larger. Dolphins weigh around 330 lb. and up to 1,500 lb.
Echolocation is seeing with sound. It is like sonar on a submarine. Dolphins use sound waves to locate their food and other things in the water. This fantastic process allows dolphins to “see” with sound.
Dolphin Social Structure
Dolphins are social mammals. They form friendships with dolphins of the same species and other species sometimes. They often show happiness, empathy, and cooperation. Isn’t that amazing?
Dolphins live in groups. These groups of dolphins are very complex. A group of dolphins is called a pod. A pod of dolphins can range from 2 to 30. If there is a lot of food in one area, dolphins may create large groups called superpods. These groups can have more than 1,000 members. Dolphins use their social groups for hunting, mating, and defending themselves.
Different group structures have been observed in bottlenose dolphins, such as nursery groups. A nursery group includes mothers and their most recent offspring, juveniles of both males and females, and adult males who are sometimes alone or in pairs. Female dolphins and adult males often only interact for short periods of time during mating season.
Dolphins are mammals. Being a mammal means baby dolphins drink milk from their mothers, and they are born alive (not from eggs). Humans are also mammals.
Adult females have babies about every 2 to 3 years. The gestation period is 10 to 18 months, depending on the species of dolphins. When calving a baby, the tail is typically born first. An “auntie” dolphin may stay with the calving mother during the birth to assist. However, this dolphin may be female or male. Within the first few days, baby dolphins can vocalize to communicate with other dolphins.
Atlantic bottlenose dolphins may nurse on their mother for 12 to 24 months. Calves nurse right below the surface to make it easier for them to breathe with the blowhole at the top of its head.
Young dolphins often form groups and share the same water area with them. Usually, females spend time with females, and males spend time with males. Males and females act differently in groups. Males are seen resting and engaging in physical activities more often. Females spend more time foraging for fish.
Dolphins have tiny teeth and they are carnivores. This means they eat meat. Dolphins eat all types of fish, squid, shrimps, jellyfish, and octopuses. The types of fish or creatures depend on the species or types of dolphins. This is also affected by where they like and the wildlife that shares their ocean habitats. Some dolphins enjoy mackerel or herring, which are both small fish.
Pods of dolphins will often work together to help hunt schools of fish. Often if you see a school of fish swimming crazily from the shore, a pod of dolphins, or maybe a shark is chasing them.
Dolphins have some natural predators out in the ocean. The sharks and the killer whales are both predators of dolphins. Since dolphins are known as some of the smartest animals in the sea, predators often leave them alone. Dolphins are more work than they are tasty.
The smallest dolphin species, or Hector’s dolphin, is the prey of the bull shark, dusky sharks, tiger sharks, and large sharks like great white sharks. These sharks normally look for the dolphins who are vulnerable or easier to catch and eat. These may be very old dolphins (slower dolphins), young inexperienced dolphins, or calves.
Orcas or killer whales are more likely than sharks to try and eat dolphins. Since they are bigger than dolphins, they will sometimes snack on them. A weird fact about this habit is the orcas are also part of the dolphin family.
The biggest predator of the dolphin does not live in the ocean, and it lives on land. HUMANS! Humans do not eat dolphins. However, anglers often kill them because they eat the same fish fishers want to catch. The anglers want to get rid of the competition for the fish.
Dolphins can also get caught in the nets. This experience is called bycatch. Bycatch is when a large-scale fishing operation happens and dolphins or other cetaceans swim into nets following fish. They get caught and are unable to get to the surface to breathe.
Habitat destruction is another “predator” of dolphins. The construction of different structures within the ocean, coastal waters, and riverbanks is causing contamination of the water. Oil contamination is one big cause of habitat destruction.
The number of healthy habitats dolphins can survive in is diminishing or going down. The River dolphins are most at risk because of habitat destruction. Dams, boat traffic, and waterfront development are destroying their habitat very quickly!
Water pollution can affect dolphins as well. Scientists have seen many effects of pollution in dolphins such as immune system suppression meaning they can get sick easier. Reproductive issues or the inability to have babies, calf mortality, development abnormalities, cancer, and other issues has an affect on dolphins too.
Dolphins are often struck by boats that are not abiding or following the rules in no-wake zones or are going too fast where a speed limit is posted. This is often similar to what is happening to manatees.
Fun Dolphin Facts
Here are some interesting facts about dolphins you may not know. Some fun facts may really surprise you! Dolphins are fantastic creatures we are still learning so much about daily.
- Dolphins use body language to communicate with other dolphins. They use their tail and flipper to slap the water on. They leap out of the water, bump each other, and spy hop.
- There are two endangered species of river dolphins. The vaquita porpoise and the northern right whale are also endangered.
- Dolphins have two stomachs. One stomach is used for the digestion of food and the other is used for food storage.
- There are 40 different species of dolphins and they live worldwide. The smallest of their kind is 3-4 feet long and the largest is 30 feet!
- Dolphins sleep with just half their brain. While asleep, part of the dolphin’s brain stays awake and is alert and active. Since half of their brain is alert, it keeps them safe from predators and keeps them breathing while asleep. Many people think dolphins have two brains because of this.
- Some dolphins can swim as fast as 20 miles per hour. Wow!
Dolphins are some of the most intelligent creatures we have on our planet. They can swim in groups or pods for protection, hunting, and babysitting. They fish together and will even migrate or swim great distances to find food.
Dolphins develop their specific whistle. The whistle helps other dolphins identify them. This behavior is like each dolphin having its own name, like you and me!
There is so much to learn about dolphins. Try finding a specific species of dolphin and learning a little more about them. You can be the next marine biologist or scientist that studies the ocean and it’s fascinating creatures!