Sharks- friend or foe

Jeremy Reaves Nov 19, 2020

Sometimes scary things aren’t so scary once you know more about them. Knowing more about them takes away the mystery and makes it easier to understand and process. While sharks can appear scary mostly due to Hollywood movies like Jaws, they are not predisposed to attack you. Here at 20K Scuba, sharks are among our favorite marine animals. While these creatures may appear scary on the outside, hopefully knowing more about them will help to alleviate some of your fears.

Sharks are completely made of cartilage – which is the same as in your nose and ears. They do not have any bones in their bodies! They use their gills on the side of their frontal bodies to filter oxygen out of the water. They have night vision and can see well in poorly lit areas. This is due to a reflective layer of tissue called the tapetum. They can also see in color.

Sharks can sense their surroundings just like bats, but they use electroreceptors to sense electromagnetic fields and temperature shifts. Most of these electroreceptors are in the snout and are very sensitive. These ampullae of Lorenzini are primarily sensitive to electrical fields (they can help a shark sense prey by detecting these electrical fields).

Some shark handlers will actually “pet” sharks and flip them on their bellies like oversized puppies who crave interaction. This is called tonic immobility and it is a trance like state which is a thought to disorientate them from being turned on the back. They feel like sandpaper due to the scale like texture of their skin. If you find the nerve to pet a shark, it is a really cool feeling, make sure to pet snout to tail as that is the direction of their scales. Sharks are 455 million years old and are older than dinosaurs! The Goblin Shark is 120 million years old and is classified as a living fossil. You can tell how old they are by counting the rings on their vertebrate similar to how a tree is aged! There are over 500 different species of sharks. Whale sharks, which are a shark not a whale, each have a unique pattern like a fingerprint and that is used to identify them. The oldest known shark on earth is a Greenland Shark believed to be 512 years old by scientists.

Whale sharks are the biggest fish in the ocean, and they are called gentle giants. These sharks eat plankton and ingest them like a vacuum. While their mouths are huge, and they can grow up to the size of a bus they have no interest in you – after all their throat is the size of a quarter! Their skin is 6 inches thick and is basically bullet proof. The dwarf lantern shark is the smallest shark and it grows to about the size of your hand.

Sharks are remarkably diverse in their reproductive method. Some sharks are born by eggs (oviparity) and some are born by live birth (viviparity) and some are even born by eggs hatching inside the mother before being born (ovoviviparity). The sharks that lay eggs have more babies then those that give live birth. It can take a long time to boost populations as some sharks do not reach maturity until 20 years old! Most sharks only breed once a year, usually at the place they were born, and give birth after a couple months. Some sharks that deliver live births have up to two-year gestation periods. All baby sharks are born with teeth and a ready to survive on their own. As a result, parents generally do not care for their young after they are born.

Most shark attacks occur in warmer water during warmer months and more often than not it is a case of mistaken identity. Humans are not in sharks’ food chain; however, surfers look like seals or turtles when they are paddling out and splashing everywhere. You are more likely to be fatally injured by a coconut falling or by falling downstairs. Cows, deer, rhinos, hippos and even our beloved dogs are far more likely to kill humans then sharks!

Hopefully, you learned something new about sharks and they may even seem less scary. We hope you enjoyed our informative article of sharks and if you have any questions or have an animal you would like to learn more about reach out to us! If you have the interest, we also offer a course called Aware Shark Conservation if you are interested in helping to preserve the shark populations and learn more about their behavior and importance in the reef ecosystem.

https://www.fisheries.noaa.gov/feature-story/12-shark-facts-may-surprise-you