Let’s be real. I’m obviously going to talk about SHARKS. Because I love them and they are super cool. And everyone should learn about them so they understand my love instead of thinking that I’m some weird, crazy person because my favorite animal is the shark. No specific shark, just sharks in general. Okay, let's get started, because I'm really excited!
First, there are currently about 400 described species of sharks. However, new species are being found all the time!
Sharks have eyes that have the same basic parts as a human eye. A shark’s eye has a retina, an iris, a cornea, and a lens like a human. They can open and close the pupil in different lighting, just like humans. And they have rods and cones so they can see in color! A shark’s eye has a mirror-like layer of tissue in the back of the eye (like a cat's eye) that increases the intensity of incoming light, making sharks more than 10x more sensitive to light than humans are. This also helps them to see in the deeper, murkier waters. Due to the structure of their eyes, scientists believe that sharks are far-sighted, able to see better at a distance than close up, which is partially why humans get attacked by sharks. They are mistaken for a seal or other food.
|Not all shark eyes look like this, but it demonstrates that they can dilate their pupils.|
Sharks are darker on the top half of their body so that they are harder to see from above against the dark ocean water. And lighter on the underside so it blends well with the lighter water closer to the surface of the ocean. It’s referred to as “countershading”, and it makes sharks extra stealthy. Like ninja’s of the ocean!
The skin of a shark feels like sandpaper when rubbed from tail to head, but silky smooth when rubbed from head to tail. Sharks skin is made up of tiny little teethy things called placoid scales, or dermal denticles. They help to reduce friction while a shark is swimming. As a shark grows, the scales don’t decrease in size, rather, the shark just grows more scales.
|This is what it looks like! Cool, right?|
Sharks do not have bones, but rather their skeleton is made up of cartilage. So, it gives support but is softer than true bone with marrow and all that jazz. Due to cartilage being softer than bone, it’s rare to find complete fossil remains of sharks.
A sharks teeth are embedded in their gums, rather than attached to the jaw, like a human. Their teeth are constantly being replaced and they grow multiple rows of teeth so as they lose a tooth, it’s immediately replaced by the one behind it, like a conveyor belt. Some sharks lose up to 30,000 teeth or more in their lifetime! The rate of tooth replacement can vary, sometimes as short as 8-10 days or as long as a few months.
|Sorry, this one is a little intense, but it was the best example I could find that showed the rows of teeth!|
It’s hard to say what the longevity of most sharks are, but it can range from 16 years (smooth dogfish shark) to over 100 years (Whale shark). Sharks have been around since before the dinosaurs (over 400 million years!) and have changed very little over the course of those millions of years.
Whew! As much fun as this is for me, I don’t know that you guys really care a whole slew. So, I’ll end here. But seriously, sharks are freaking cool. Fall in love with them, okay? Just do it.
I'll leave this clip here for you... I was obsessed with it in... I want to say it was 7th grade? when I found it. And I watched it over and over and over again. This is a prehistoric shark that they found off the coast of Japan. It's literally a living fossil! It has frilled gills, you guys. Sadly, she died when they were trying to transport her. But, this is what spurned my love of sharks. After I watched this, I read countless articles and research blogs and things about sharks. I LOVE SHARKS.
I hope you enjoyed and learned something new! Have a lovely day!
Also, here are the links and whatnot to where I got my pictures and brushed up on a few things. Just in case, and because that's the right thing to do, dontcha know?