24 SHARK FACTS – Things You Didn't Know About Sharks

24 SHARK FACTS – Things You Didn’t Know About Sharks

Everyone knows a thing or two about sharks, but what if I surprise you with facts you probably didn’t know about these creatures?

Of course, most people have seen the 1975 American thriller film “Jaws” based on a novel by Peter Benchley with the same name. With this film portraying the great white shark as a voracious man-eater, many people dread the common mention of “sharks”.

I found out on many interactions with people that the mention of sharks creates a mental image of jagged teeth, a robust body, dangerous predator. But, in reality, this is not the case. There are more to sharks than what you imagine them to be.

Now, let’s take a look at 24 shark facts that will amaze you!

1. There are Over 500 Known Species of Sharks

In case you were imagining shark to be just one sea creature, know there are many sharks! The different species of sharks differ in appearance and behavior. They have different sizes, the body builds, feeding habits, and found in different habitats.

These sharks are classified into different families and genera. Each with a unique trait for proper identification. So, when next you hear shark, let your mind go over the particular mentioned.

2. Sharks Have No Bones

Sharks are Elasmobranchs which include cartilaginous fishes, skates, and rays. This means that their skeletal system is made of cartilaginous tissues instead of bones. Cartilage is a flexible, translucent tissue that is somewhat elastic.

If you want to understand what cartilage is better, touch your ears and the tip of your nose. Of course, those parts of the human body are made of cartilage. In sharks the whole skeletal system consists of cartilage, however, they still fossilize.

As this shark gets older, most of them deposit calcium salts in their cartilaginous tissues strengthening it. This calcium mineral helps the skeletal system of sharks to fossilize. The jaws when dried looks solid just like bones. More so, because the teeth have enamels, they too fossilize.

3. There are Very Small Sharks and Very Large Sharks

The sizes of different shark species range from the small ones that can fit in a home aquarium to the very large one that can swallow a full-grown human. The dwarf lantern shark is likely the smallest shark with a maximum length of 7.9 inches (20 cm), while the largest shark the Whale shark grows to a length of about 60 feet (18 m).

4. Sharks Swim in All Water Levels

From the surface of the sea to depths close to 10,000 feet (3,048 m) you will find different species of sharks. Some sharks do not swim up to the water surface where anyone can see them.

The Greenland shark for example lives in great depths just above the freezing environment. Except you go down to a depth of 6,000 feet (1,828 m), you won’t likely encounter a Greenland shark.

5. Most Sharks Have Well-developed Eyesight

Most species of sharks see well in areas with poor light. Their night vision is exceptional and they can identify colors. There is a reflective layer behind the eyes of these sharks known tapetum. This tissue helps the sharks a lot with sight when they swim to dark environments.

6. Sharks Have Been Around for Millions of Years

The oldest existing shark today is the goblin shark (Mitsukurina owstoni). Scientists hypothesize that this deep-ocean species of Lamniform dates back to about 125 million years ago.

The first appearance of sharks in the ocean goes way back to around 455 million years ago. Scientists were able to suggest through the carbon dating of fossil scales of sharks found in Australia and the United States.

7. Sharks Experience “Tonic Immobility”

When you flip a shark over with the underside facing up, it tends to go into a half-conscious state. The shark appears more like hypnotized and does not respond to external stimuli. This state in sharks is known as tonic immobility. Researchers who work on sharks turn them upside down to conduct their research.

8. Sharks Live in All Oceanic Waters

Sharks occur in the open sea, shallow waters, and brackish estuaries. They inhabit coral reefs, rocky reefs, and sandy flats. Their geographical distribution extends throughout the oceans of the world. Some shark species can even migrate to freshwaters.

9. While Some Sharks are very Weak at Swimming, Others are Strong and Active

Some sharks such as the nurse shark and the wobbegongs are lazy and lethargic. They rarely migrate and maintain a favored resting spot for a very long time. These sharks maintain the home zone within a defined radius.

However, on the other hand, sharks such as the great white shark (Carcharodon carcharias) travel very great distances. These sharks need to continuously swim to breathe. The great white shark has been observed to swim from one end of the ocean to the other end.

10. The Skin of Sharks are not Smooth

Looking at sharks from far or from a photo, you might think that these creatures have smooth skin. Far from that, the skin of sharks is covered with dermal denticles or otherwise called placoid scales. These tooth-like structures pointing toward the tail help sharks reduce drag as they swim. They are more like sandpaper.

11. Not all Sharks are Cold-blooded

While many shark species are cold-blooded, some species are still warm-blooded. One among the warm-blooded shark species is the great white shark.

12. Sharks Exhibit Social Behavior

Species of shark relate to each other differently. Some are more complex than others. Social grouping among sharks mostly associates with feeding or mating. However, some shark species hang out with another simply they enjoy each other’s company.

For example, the lemon shark keep friends. This shark species after years of observation proved to make friends among their species. Friends hunt together and communicate with one another. This relationship associates with no survival or hunting advantage, thus showing the complexity of their social life.

There are many other shark species with various complex social behaviors.

13. Sharks Have Diverse Means of Reproduction

Different shark species have different means of reproduction. Some lay eggs (oviparous) examples are zebra sharks, horn sharks, the catsharks, and some species of epaulette sharks.

The cookiecutter sharks, thresher sharks, great white sharks, nurse sharks, and many others are ovoviviparous. This means that their eggs hatch within their body just before they give birth to the young one alive.

Other shark species such as the bull shark, whitetip reef shark, lemon shark, blue shark, hammerhead sharks, and so on are viviparous in nature. They give birth to their young ones alive with the developing embryos feeding from their mother.

14. Some Sharks Have Very Unique Coloration

If you have heard of blue sharks, you may wonder if these sharks are truly blue. Well, let me surprise you; blue sharks are truly blue. Their dorsal side shows a brilliant blue coloration. Though the underside (ventral side) has a bright white color which contrasts with the blue. These colors serve as camouflage for the shark.

Another shark on this table is the lemon shark which displays a bright yellow color on the upper side. While the underside is yellowish-white.

The coloration of these two sharks and others is unique compared to most sharks that have a brownish, olive, or gray color.

15. The Megalodon was Once the Largest shark

Before its extinction about 2.6 million years ago, the Carcharoles megalodon was the largest shark. This shark grows larger than the whale shark. The look and behavior of this shark are not certain, however, there is a wide belief among researchers that the megalodon looked like the great white shark.

It is regarded as one of the most powerful predators to have ever lived. All that is known of the megalodon comes from the discovered fragments of its remains. Even the maximum size is still under debate among researchers.

16. The Spot Pattern on the Body of Each Whale Shark is Specific to it

Whale sharks have spots on their body, but the pattern of these spots differ from each other. Just like the human fingerprints, the pattern is unique to a particular whale shark. The whale shark is the largest fish inhabiting the ocean.

17. Sharks Replace their Teeth Several Times in Their Lifetime

At some points, the sharks’ teeth tend to get blunt, these sharks shed them off and grow a new set of teeth. Most sharks replace their teeth individually as they lose them, while few others lose their whole teeth at once and then replace them.

Sharks keep shedding and replacing their teeth throughout their lifetime. Some Carcharhiniformes lose as much as 35,000 teeth in a lifetime.

18. Sharks Deposit Growth Bands on Their Vertebrae Which Helps in Determining Their Age

By counting the concentric pairs of growth bands on the vertebrae of a shark, scientists can determine their age. That is, if a shark has 5 pairs of bands, then it should be 5 years.

This method of age determination is not always correct. According to recent studies, there is a need to obtain “validation” to be sure of the actual age of the shark. Validation is the rate at which a particular shark deposit the pairs of growth band.

Sharks deposit growth bands at different rates, moreover, the rate of deposition may change over time. This is why researchers need to study each shark species to figure out this rate of deposition.

19. Sharks Have a Special Organ for Electroreception

The ampullae of Lorenzini is a special electroreceptor organ which helps sharks to pick weak electrical signals. This ability helps them, especially when hunting. They can track down hidden prey since the prey generates electric fields which this organ can detect.

This organ also helps sharks in detecting temperature changes in the ocean.

20. Sharks are Not as Dangerous to Humans as You Think

Most shark species would not attack humans for any reason. The few species assessed as potentially dangerous to humans rarely attack them. Humans are not favored prey for sharks. Even sharks can be more dangerous to themselves than humans.

Embryos of the Sand tiger shark cannibalize their siblings in the womb. And, many other sharks are a threat to the juveniles of vulnerable species. So, sharks attack themselves more than they attack humans.

Far from what “Jaws” portrayed sharks to be, these creatures mostly attack humans when they perceive a threat or are provoked.

21. Sharks Can Protect Their Eyes Through Ocular Rotation or Nictitating Membrane

Some shark species which include the great white shark uses ocular rotation to protect their eyes. This is a process where the eyes roll completely back exposing tough cartilage that shields the eyes. When this happens the eyes of the shark go white. They do this, especially when biting into prey.

Other species have a protective third eyelid called the nictitating membrane which helps to protect their eyes.

22. The Large Liver of Sharks Helps Them to Maintain Buoyancy

Sharks have very large livers which cover the most part of their underside. This liver amounts to about 25% of the shark’s body weight. The liver contains oil and helps sharks with buoyancy.

In bony fish is the air-filled swim bladder enabling them to maintain. However, this is lacking in sharks and the liver takes up the function.

23. Humans are More of Threat to Sharks Than They are to Humans

The massive decline in the population of sharks is largely a result of human activities. Each year, about 100 million sharks are killed by fishermen who cut their fins for sale. The fin of sharks is the main material for shark-fin soup.

After finning these sharks, they throw them back into the ocean to die. This practice is being discouraged as conservation actions are put in place to save sharks.

24. All Sharks Have Multiple Gill Slits and Jawbones

This feature is common with all sharks. The gill slits are visible from outside and mostly located close to the head. The jawbones are also present in all sharks containing their teeth. These are what makes a shark!