Similarities and Differences of Sharks and Dolphins

The claim that I will be investigating is “Sharks and dolphins have evolved similar characteristics”.


The above claim represents how people believe that sharks and dolphins have evolved will impact on how much people know about sharks and dolphins. Sharks, which evolved several million years before dolphins, first adapted to the water with their hydrodynamic bodies. Dolphins, which evolved long after sharks from land mammals, adapted to the water with similar physical characteristics.

Research Question

In this investigation I will be investigating the different between sharks and dolphins.

Justified argument and evidence

The main evidence in relation to dolphins and sharks has been obtained from Dolphins adaptions. The ancestors of dolphins were animals that once lived on land. No one is quite sure why they turned to the sea, but they did so about 50 million years ago and never returned to land. When this happened, the dolphin’s ancestor had to slowly adapt to its new environment. Its front legs became flippers and its tail became flukes. Its back legs diminished till they were absorbed into the body. Even now, if a person looks at a dolphin’s skeleton the floating bone that is what is left of the leg, vestigial, floating pelvic bones can still be seen. Now and then there’s a baby dolphin or whale that’s born with tiny hind legs, but this is rare. Mammals also have fur or hair and dolphins are sometimes born with hair around their beaks, but they lose this hair not long after birth. The adaptive features of sharks have enabled the species to survive in waters all over the world for more than 400 million years. This image shows that sharks and dolphin had a common ancestor a long time ago, but they are only distantly related now.

Sharks and Dolphins also have very contrasting reputations with humans. Sharks are often associated with fear due to the attacks on people that have occurred throughout the years. While not a natural food source for sharks, humans, especially surfers and their boards, are often mistaken by sharks as large fish due to their poor vision. The blockbuster franchise Jaws has helped popularize the terror over shark attacks, and the decline in their numbers has been attributed to shark hunting and killing carried out by humans. Sharks are also solitary hunters and would even kill each other as prey. Meanwhile, dolphins are often regarded as helpers of humankind, even going as far back as Ancient Greece. Because of their friendly countenance, they don’t view humans as a threat and therefore won’t attack even when provoked. Some reports by victims include instances of a group of dolphins forming a protective ring around a human in order to prevent a shark from attacking, or else lifting a drowning human to help him/her breathe. The theory is that dolphins recognize humans as fellow mammals and therefore will come to our aid.

The similarities between sharks and dolphins are side fins, a dorsal fin, and a torpedo-shaped body. Another similarity is there shape of their teeth both of there teeth are serrated the reason why they are serrated is so that they can grab on to their pray. As there are similarities there are some different even though they these two creatures both in habit the same vast ecosystem of the ocean but what is the difference between sharks and dolphins such as Sharks are cold-blooded, and dolphins are warm-blooded. Another is that go to the surface and breathe atmospheric air in though their blowhole, but sharks use their gills to get oxygen from the water in which they swim. Another different is that dolphins nurse their young where sharks don’t nurse their young and another different is sharks don’t have hair where dolphins have hair around their nose. Another different is that sharks are made of cartilage where dolphins are made of bonds. The simplest way to put it is that sharks are fish and dolphins are aquatic mammals. Physically, their fins look quite similar from a distance, but a shark can have as many as four unpaired fins with a second dorsal fin set farther back from the more prominent first dorsal fin, while a dolphin only has one dorsal fin. So, if you see two fins sticking out of the water, you better swim as fast as you can! The shark’s fin shape is quite broad and sticks straight up, while a dolphin’s fin is curved backward to create a distinguishable arc. As for the movements in water, both are terrific swimmers with the shark using a side-to-side tail movement while dolphins propel themselves forward through the up-down motion of their flat tails.


The task that we were given was to research a claim and come up with a question to research. The research I came up with was what differenties and similarities between sharks and dolphins. So, then I had to explain how they were the differenties between sharks and dolphins. So, similarities that sharks and dolphins had was the side fins, a dorsal fin, and a torpedo-shaped body and some differenties were sharks do not nurse the young, but dolphins do nurse there young. The source that I used where reliable the reason they were reliable was because they where consistent with there information. However they did not have authors listed.

07 April 2022
Your Email

By clicking “Send”, you agree to our Terms of service and  Privacy statement. We will occasionally send you account related emails.

close thanks-icon

Your essay sample has been sent.

Order now
Still can’t find what you need?

Order custom paper and save your time
for priority classes!

Order paper now