Sharks have been around for more than 400 million years, making them one of the oldest yet most fascinating living creatures here on planet Earth. They come in various sizes and can be found in almost all of the world’s oceans. They have even adapted to various habitats, from shallow coastal waters to the open ocean and deep sea trenches.
Despite being incredibly powerful predators, with some reaching speeds of up to 50 kilometers per hour, their species remain threatened by human activities such as overfishing and shark finning.
Even with their reputation as ruthless and relentless creatures, however, sharks are actually incredibly important to the ocean’s food chain and are vital to keeping the ecosystem in balance.
Here are some more facts surrounding these fearsome predators:
Surprising Shark Facts
Photo by David Clode
- Sharks are the oldest living jawed vertebrates and they share this trait with humans, too.
- Sharks belong to a class of fish called elasmobranchs; that is, their body is made up of cartilaginous tissues instead of bones.
- Shark teeth have enamel, too.
- Sharks can still fossilize, even if they have no bones. This is because they deposit calcium salts in their skeletal cartilage, as they age.
- The smallest shark species can be about the size of a hand. This is known as the dwarf lantern shark.
- The Helicoprion is an extinct shark genus that had jaws that were similar to a circular saw.
Photo by Chase Baker
- A shark’s tapetum lucidum (a reflective tissue layer in its eyeballs) gives it an incredible vision, especially in the dark.
- Sharks can live in diverse habitats, even in the Arctic.
- A shark’s placoid scales or dermal denticles in its skin are responsible for its texture is similar to sandpaper.
- Greenland sharks go partially blind because of parasites that often attach to their eyes.
- Some of the largest living sharks are Great White Sharks, and they, unlike most cold-blooded sharks, are partially warm-blooded.
Photo by Zander Janzen van Rensburg
- Megalodons gave birth to live young who were, at birth, about the size of an average basketball player.
- Whale sharks reach maturity at about 30 years of age and are about 9 meters long.
- Scientists use the rings on a shark’s vertebrae to determine their age.
- Most sharks have colors that vary between gray, brown, or olive, with the exception of the blue shark, which is really actually blue in color.
- Like human fingerprints, whale shark spot patterns distinguish each species from the other.
- The rare and deep-water living Megamouth sharks did not hunt on larger prey. Instead, they ate plankton and tiny shrimp-like crustaceans.
- Despite its warm conditions, you cannot find a whale shark that lives in the Mediterranean Sea.
- Basking sharks feed only on a particular type of diet: zooplankton.
- Whale sharks do not have spiracles, which is a common body part found in most sharks that allow them to breathe while they feed or rest at the bottom part of the ocean.
- Shark teeth differ but are mostly classified into four types, namely: dense-flattened, needle-like, pointed lower teeth with triangular upper teeth, and non-functional.
- Some sharks reproduce by giving birth to live young, while others lay eggs that hatch outside their mother’s body. Some species even reproduce asexually.
- The thickened skin of female sharks is an adaptation they have developed as male sharks bite into their skin during mating to assume the proper position.
- Scientists turn sharks gently on their backs to help them enter a state of relaxation, allowing them to better study and understand these species.
Frequently Asked Questions about Sharks
What are sharks afraid of?
They may often be seen as apex predators, but that does not mean that sharks are not afraid of anything. In fact, there are a few things that can actually scare a shark away.
For one, sharks are usually sensitive to noise, with a few select species noted to be more sensitive to underwater sound than others. This is because sharks are one of the few creatures with impressive senses, including the sense of hearing.
Like other food chain species, sharks also tend to be wary of larger predators, such as killer whales, dolphins, and other large fish.
Surprisingly also, some sharks have been observed to be fearful of human contact, so be sure to maintain a safe distance if you’re ever lucky enough to encounter one.
Can sharks sleep?
Sharks are a fascinating species that have been around for millions of years, and their behavior is still relatively mysterious.
One known thing is that sharks can indeed sleep, but not in the traditional sense. Sharks need to rest, just like any other animal, and they do so by slowing down and becoming less active or by staying motionless on the seafloor.
Sharks can enter a type of light sleep where they can still be aware of their surroundings. This type of sleep helps sharks conserve energy while they rest, as they may not have access to food sources while they sleep.
However, sharks have to be careful, as they are vulnerable to predators while they are in this state. Therefore, they may not sleep for extended periods of time but instead opt for short, light naps to stay safe and conserve energy.
What is unique about a shark?
Sharks have an impressive ability to detect the weak electrical fields of their prey. This is due to their ampullae of Lorenzini which are specialized jelly-filled pores that connect to the nerves around their snout.
This sensing organ also gives them the ability to detect even the smallest electrical impulses generated by their prey, allowing them to hone in on the source.
This remarkable ability is also used to detect changes in water pressure that could indicate the presence of prey, or even the presence of predators. Sharks can also sense changes in temperature, allowing them to pursue prey in deeper and colder waters. This combination of senses makes sharks one of the most efficient predators in the sea.