Basic Shark Facts For Scuba Divers – By Monique Mancilla and Daniel Ponce-Taylor


For many people, the word “shark” conjures the image of a dangerous animal, a killing machine out to attack humans.
This could not be further from the truth. In fact, a person is more likely to be struck and killed by lightening than attacked by a shark.
Worldwide, sharks only kill 4 – 5 people a year.
Instead of fearing sharks, divers should realize that sharks are fascinating animals that play an essential role in maintaining balance within marine ecosystems.
Here are some interesting facts that divers should know about sharks.

Are Sharks Fish?:
Although sharks, skates, and rays do not have scales, they are still classified as fish.
These creatures are all members the cartilaginous fish group; instead of bones, their bodies are supported by cartilage (like a person’s nose).
Cartilage is more flexible than bone, giving shark fins an almost rubbery appearance.
As migratory fish, sharks spend most of their time in open water.
With more than 400 types of sharks on the planet, shark species demonstrate great diversity in size, appearance, habitat, and behavior.

Sharks Frequently Lose Teeth:
One of a shark’s most recognized characteristics is a mouth of sharp, scary teeth.
As an apex predator (meaning that sharks are at the top of the food chain),
a shark’s teeth need to meet the challenge of eating the wide variety of animals below it on the food chain.
Without teeth, a shark would be unable to survive, so sharks have an interesting way of dealing with broken or lost teeth.
Shark teeth are embedded in the animal’s gums and can come out of a shark’s mouth relatively easily.
Rows of replacement teeth grow along the jaw and move forward when a tooth needs to be replaced.

Do Sharks Really Eat Humans?:
With a keen sense of smell, sharks can detect blood in the water in quantities as little as one part per million.
Sharks have very specific food preferences and humans are not at the top of their menu.
A shark will either vomit out an unfavorable food item or its stomach will turn inside out to eject it.
Of over 400 shark species, great white, tiger and bull sharks are responsible for the majority of (the very few) attacks on humans.

Sharks Have a Sixth Sense:
Sharks have a network of jelly-filled pores which are used to detect electromagnetic fields produced by other animals.
This can be though of as a sixth, “electromagnetic sense”.
A shark’s electromagnetic sensing cells are known as the ampullae of Lorenzini, and can help a shark to find its next meal.
Sharks are the most electrically sensitive animals on the planet, and are even capable of finding prey hidden in sand by honing in on the prey’s electric field.
Sharks can also sense the electric fields generated by ocean currents, aiding them in navigating the ocean.

Fun Sharks Facts and Trivia:

  • A shark on land would be crushed by its own weight. Sharks lack a ribcage to maintain body structure.
  • Most sharks have eight fins. Despite this, they cannot back up. Their fins do not allow them to move tail-first, which means they eventually drift over objects directly in front of them.
  • Despite its numerous teeth, a shark’s digestion is very slow.
  • Many shark species must maintain constant motion to keep water flowing over their gills. If they stop swimming, they do not receive sufficient amounts of oxygen to survive.

Reduce the Risk of a Shark Attack While Diving:
If you are worried that you are going to be attacked by a shark, here are a few tips to decrease the already tiny chance of being attacked by a shark.

  • Avoid diving in waters with poor visibility as it increases the chance of a shark mistaking you for something it normally eats.
  • Avoid diving at dawn and dusk, as this is when many species of sharks are most active.
  • If a shark is spotted, find your dive buddy and stay together. Sharks are more likely to attack solitary individuals than members of a group. Seals use the same defensive strategy with white sharks in South Africa.
  • If you are lucky enough to see a shark while diving, stay calm and keep an eye on it.
  • If you do not feel safe with the shark then slowly swim to the dive boat or shore to exit the water

The Take-Home Message About Diving With Sharks:
They are a beautiful but threatened group of species.
Instead of fearing sharks, divers should cherish swimming in presence of these amazing and increasingly rare animals.
Each year, up to 100 million sharks are killed for their fins, jaws, teeth, meat, or by accident .
On average, for every human killed by sharks up to 20 million sharks are killed by people.
Divers, and people in general, should stop fearing sharks and start protecting them.