• Jessica Evans

5 reasons why sharks are cool, not scary

Sharks have an unfairly bad reputation. Ever since Jaws debuted, beach trips have been accompanied by the silent question:"What if there's a shark in there?" The recent appearance of The Meg in cinemas hasn't made it any better. If you haven't seen those movies - don't watch them. All you're missing is a couple of hundred minutes of terror whilst some over-dramatised shark munches on a bunch of people. Sharks are actually incredible creatures! Soooo, to counter-act their negative image here are some reasons sharks are cool as heck! As always, I hope you learn, but more importantly - enjoy!

Meet Meg. She's a character I've (primitively) created to help demystify sharks, and to make them less frightening.

1. Yo-yo swimming

Some sharks, namely the shortfin mako shark (Isurus oxyrinchus), the great white shark (Carcharodon carcharias), and the blue shark (Prionace glauca) , all exhibit yo-yo swimming, or oscillatory swimming. This just means that while they swim around, going about their sharky lives, they move up and down, between the surface and lower down in the water column. Kind of a funny image, right? Scientists think they do this because the surface is warmer and the sharks like to be cosy and warm after swimming in the colder, deep waters where magnetic fields are more pronounced - which brings me to point 2.

2. Magnetoreception

This is something that's been under debate in the scientific community for some time. It's possible that sharks navigate the sea and map their migrations according to the geomagnetic field (the earth's magnetic field). They do this by using special sensors that detect changes in the field they experience based on where they are, with the magnetic field being stronger at the two poles than at the equator. A lot still needs to be discovered about the way sharks might do this.

3. Electrosensitivity

Sharks and rays can detect prey using electrical signals. When an animal moves, it gives off small electrical pulses called bioelectric pulses. Sharks are capable of detecting these pulses, without necessarily seeing their prey. The organs that allow them to do this sound a lot like pasta to me. They're called ampullae of Lorenzini. Together with smell, electrosensitivity is one of the primary senses sharks use when hunting.

4. Counter-shading

Sharks, like many other organisms, exhibit counter-shading. In other words, the surface most exposed to light (the top surface or dorsal side) is darker than the bottom or ventral side. Prey species use this to match the scenery above - the lighter bottom side matches the brightness of the sky, making them more difficult to see. The lighter bottom also reflects light, concealing an animal's silhouette. Predator species, like sharks, use counter-shading to match the blue below. The fact their dorsal side matches the background makes them harder to see from above, enabling them to surprise prey from below.

5. They really aren't interested in eating you

Sharks are just fish. They swim around and eat what they instinctively know - or think - they must. Sometimes that looks like a person. Keep in mind that sharks have poor eyesight. If they see something that looks similar to a seal or a turtle, like say, a human on a surf board, they'll want to munch it. It isn't an evil thing sharks do - they don't set out on their day with the aim of terrorising beach-goers and ruining holidays or surf days. They have an unjustly disproportionate reputation when you take into account the number of deaths they cause every year. You're more likely to be murdered by another fellow human, or even a hippo, than you are to be killed by a shark. Bill Gates made a handy infographic on this. Remember that when you enter the sea you're entering a different domain. It's not your home, so enter with respect, and try avoid being attacked by a hippo (or a human).

#shark #jaws #themeg #greatwhite #blue #sharkfacts #electricfield #magneticfield #magnetoreception #electrosensitivity

©2018 by Bite-sized Sci | Jessica Evans