[1] The Shark Diary || Sharks - life, food, anatomy, threats, types and the like

I have always had a passion for sharks, and now that I am getting older, I am able to start cultivating that passion and begin figuring out ways to aid and help conserve sharks and in turn the ocean ecosystem. Recently, I have been watching loads of shark documentaries and my passion for sharks has just kept growing. So what are sharks? food, habitat, lifecycle. How do they swim? anatomy. What threats are sharks facing? Humans and environmental issues.

So what are sharks? Sharks are a type of fish that make up a part of the subclass Elasmobranchii which is a part of the class Chondrichthyes [2], making them a sister species to skates and rays [1]. Sharks are characterized as having 5 to 7 gills. They also have tough skin that is made up of small tooth like scales [2], these are called dermal denticles. Sharks also do not have a swim bladder, (the bladder used to keep fish in one place in the water), therefore they have to keep swimming in order to stop themselves from sinking to the bottom. Sharks are also apex predators, meaning they are at the top of their food chain and aid in keeping the ecosystem running smoothly. 

Sharks vary largely in size, ranging from the dwarf lantern shark, which is the size of a human hand, all the way up to the 12m long whale shark. In order to survive in varying temperatures, sharks are cold-blooded, or poikilothermic [5]. This means that their body temperature is the same as the water in which they live in, this stops them from losing any heat from their body core.

 It is thought that there are more than 500 known species of sharks, due to this they are grouped in accordance to the following table:

[3] (this is not all 500 species or sub species)

Sharks can be found in almost every part of the ocean, at various depths and depending on the species, they feed on anything from plankton, to fish, to other sharks, and any dead animals they find, they are opportunistic. For example, Basking sharks and Whale sharks have large sieve like mouths which they use to filter plankton. On the other hand, Thresher sharks and Mako sharks hunt schools of fish, tending to try and pick off the outside fish that swim in large bait balls. Sharks like Hammerheads, have been seen using their heads to pin stingrays to the seafloor to eat them. As well as the usual senses, sharks also have a sixth sense, this is called "amupllae of lorenzini'' [4]. These are found in the snouts of the shark and help them detect the electric field of their prey, helping them hone in during the final stages of their attack. 

Out of the 500 species, 143 of these are recognized as under threat by the IUCN. This ranges from endangered to critically endangered [4]. The biggest threat facing sharks to date is the increased demand for fins to make 'shark fin soup'. Shark finning is the process of catching sharks, cutting off all their fins while they are still alive, and then throwing them back into the ocean (still alive) where they suffocate or drown due to not being able to move from the seabed. Sometimes they get eaten alive by other sharks as they are unable to defend themselves. 

It is thought that approximately 100 million sharks are caught and finned annually and this practice affects all types of sharks. On average, shark fins sell for about $400USD however Basking sharks and Whale sharks are considered trophy items and therefore their fins sell for about $10,000USD to $20,000USD [6]. This in turn causes overfishing within shark populations and creates unstable ecosystems. Sharks are also sometimes caught as by catch and are affected by climate change and ocean acidification [7]. 

As you can see, sharks are very important species and are under a lot of threat from overfishing and climate change. I want to start these shark diaries in order teach and educate and even learn more myself about sharks so that we can all do our part in trying to protect these wonderful creatures. I will also address stigmas surrounding sharks and do some myth busting, because sharks are really great animals. 

I hope you enjoy this mini series and if you have any ideas for more ocean or environment posts, comment below and I can look into it :)

Lets change the world together, one step at a time. 

A Little House Plant 🌱

[1] https://en.wikipedia.org/wiki/Shark
[2] https://www.britannica.com/animal/shark
[3] https://www.sharks-world.com/types_of_sharks/
[4] https://www.wwf.org.uk/learn/fascinating-facts/sharks
[5] https://science.jrank.org/pages/6113/Sharks-Temperature-regulation.html
[6]https://en.wikipedia.org/wiki/Shark_finning#:~:text=Shark%20fins%20are%20among%20the,to%20%2420%2C000%20for%20a%20fin.
[7] https://www.worldwildlife.org/species/shark