Sharks and dolphins are both aquatic animals who will swim close to the surface of the water.
When they do this their fins will appear above the surface, if you happen to be close enough to make out the fin then you may immediately panic and believe a shark is close, only for it to turn out to be a dolphin.
So how is it possible to make out if that fin heading right for you is a shark or a dolphin.
The two fins share common characteristics but upon closer inspection there are some very distinctive differences.
Of the two species dolphins are considered to be the more playful and curious this in turn causes them to get closer to humans than sharks would.
Within this article we will teach you the differences so the next time you have an encounter with a fin you will know who it belongs to.
The Distinctive Differences
The biggest difference between the two is that shark fins are angled, the leading edge of the fin comes out at an angle whilst the trailing edge is straight.
The dorsal fins of a shark are broad and protrude straight from the back.
A shark fin has a triangular notch at the base of the back that separates the part of the fin from the back of the animal.
Depending on the species of shark they can have up to four unpaired fins on their body. The second dorsal fin will only be visible when the shark is under the surface.
This one is the smaller of the two so you will need to look at it much more closely to identify it.
Sharks have a higher vertical tail that will move from one side to the other. The distinctive differences between dolphins and sharks is in their dorsal fins.
Some dolphins have dorsal fins that are rounded in comparison to sharks who have a straighter edge at the end of their dorsal fins.
Shark fins will tend to be triangular in shape.
This leads to the edge of the dorsal fin having a small curve, this depends on the species and the back edge of the fin points in the direction of the shark’s tail which is either square or flat.
Certain shark species will have rounder fins such as the hammerhead shark however it is not easy to make out this difference from being in the water or on the beach.
When the dorsal fin breaks through the water’s surface it is followed by a smaller tail fin that sits a few meters above sea level.
If you see this then it is for certain a shark.
The ends of the hammerhead shark’s dorsal fin are more similar to that of the dolphin; they are more rounded as opposed to the bent or hooked shape fins typically associated with sharks.
The triangular dorsal fin should provide you with enough contrast to be a warning.
The tail fin should not be enough of an indicator to know if the animal is a shark.
This is due to the tail fin not being visible in smaller sharks who more commonly swim closer to beaches.
The larger the shark’s fins the more they differ from dolphins and take on the more commonly associated shark fin look.
Sharks are usually solitary animals and feed in surf zones, if there happens to be several sharks in an area they will not swim together like dolphins.
Sharks swim will tend to swim in one direction with a constant motion, this is a clear difference to a dolphin as a shark will not bob around and play in a wave like a dolphin will.
When dolphins are moving close to the surface it is an indication that they may need to break through the surface to breathe.
In contrast sharks will look solely for food to hunt and thus will not move up and down in the water.
Both dolphins and sharks have complete control over their fins but their methods of gliding through our oceans are very different.
Dolphins have a broad horizontal tail that allows them to fly through the water. The dolphins dorsal fins have a visible bow and a curved tip.
Unlike sharks, dolphins are social animals and are known to swim in pods, when you spot a dolphin you can be assured that there are likely more in the vicinity.
Dolphins are not only confused with sharks but have also been confused to be whales and even manta rays.
Manta Rays however, have two fins that will protrude from the water parallel to each other and have much smaller fins than dolphins.
The opposite is true for whales who have no protruding fins.
The first part of a whale you will see when it breaks the water is the body, the much larger nature of a whale in comparison to a dolphin should be an easy tell too.
Minor Similarities And Differences
Some other differences between sharks and dolphins are that sharks have gills that allow them to breathe underwater whereas dolphins have a blowhole that forces them to resurface to breathe.
Both sharks and dolphins have what is known as a counter shadow.
A counter shadow is the animals belly illuminates their back, this is helpful in the ocean as it allows them to easily blend in with the marine environment around them.
Dolphins are required to live close to the surface so they can breathe air, while sharks will spend their entire lives under the water in oceans, coastal waters, coral reefs or even rivers in some cases.
Dolphins are one of the most social animals on the planet and will actively seek to live in a pod.
Sharks are more lonely and do not communicate with other sharks like dolphins do by making noise.
Both dolphins and sharks are carnivores and are opportunistic hunters, eating anything that is available to them and easy to catch.
Their diet consists of fish, crustaceans, cuttlefish and shrimp.
Sharks however will also eat different types of shark, marine mammals and plankton in the case of the whale shark.
So next time you are sitting on the beach or swimming out into the ocean and you spot a gray fin on the surface of the water, you can hopefully see some indication whether the animal is a shark or a dolphin.
But, it is always best to just be safe than sorry so if you are not sure it’s best to leave it alone and not swim over and investigate the fin.
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