By Pauline Odhiambo
Sharks are some of the fish species with unique characteristics and behaviours. They are found around the world including in African countries such as South Africa and Somalia.
Over the years, thousands of tourists travel to South Africa’s Western Cape each year to catch a glimpse of the ocean’s top predator from underwater cages.
When you think of the dangers of the sea, sharks often top the list.
These resilient aquatic creatures have had a bad reputation for while now - often depicted in movies as extremely dangerous.
But many marine biologists believe that they are, in fact, more scared of humans than the other way around.
But some species have been declining at an alarming rate. The Great White Shark, which is often depicted as a ruthless killer, is among the most vulnerable species with only about 3,500 left worldwide, according to the World Wildlife Fund.
Often hunted for their teeth and fins, their numbers have decreased due to trophy hunting and other harmful fishing practices.
Shark Awareness Day is celebrated on July 14 to create more awareness on the need to protect shark species.
Sharks date so far back in history that many scientists refer to them as ‘living fossils.’
Some scientists believe sharks are older than trees and dinosaurs, with the latter having roamed the earth only 230 million years ago, according to World Wildlife Fund.
Sharks, on the other hand, have been on the planet for more than 420 million years now, the conservation organisation says.
Sharks are a type of fish known as elasmobranchs. This means that instead of bones, their skeleton is made up of cartilage – the same thing the human ear is made of.
Sharks, if flipped upside down, go into a trance-like state similar to that of being hypnotised. This is called tonic immobility.
Delicacy
A shark usually doesn't bite a person more than once. On the other hand, it is estimated that 100 million sharks are killed per year through human activity, according to the World Wildlife Fund.
Many species are classified as ‘Vulnerable’, ‘Endangered’ or ‘Critically Endangered’ by the International Union for Conservation of Nature (IUCN).
Sharks are a delicacy in different parts of the world and are often targeted for their alleged medicinal properties.
Sharks have electroreception – an ability to detect electrical currents. They use this to detect the movement of their prey.
Giant vs dwarf
They have sensors, known as ampullae of Lorenzini, which are small pores on the snout and other areas of the body.
Sharks can grow up to 9-12 metres or 40 feet, which is roughly the size of a school bus.
But they can be small as well. The dwarf lantern shark is thought to be the smallest species, growing up to approximately 6 inches or 20 centimetres in length.
Ecosystem
It can fit in the palm of an adult human and is found in 200-400m of water off the coasts of Colombia and Venezuela.
Cookie-cutter sharks feed by latching on to whales, seals and other large fish; scooping out a circular chunk of skin and blubber.
The result is a cookie-cutter shaped hole in the whale which eventually heals over time
Without sharks, the rest of the food chain and the ecosystem would be altered. Sharks prey on sea turtles which eat seagrass that is important for carbon storage.
