Biology Is Weird — The 1%
You know when you have a kid eating a cracker and suddenly they want to share with you, but it’s all wet and gross and you can’t actually eat it? Or when you catch the scent of a hot, tasty meal and your mouth can’t help but water. And we all licked an object or two so our siblings wouldn’t get it. What do these three scenarios have in common? Saliva.
But what is saliva? Clear like water, slimy like… well, slime and babies seem to have it in excess. Saliva is actually 99% water and 1% other stuff. Other stuff includes mucus, proteins, electrolytes, minerals, acids and antibodies. Yes, that is a lot to fit into 1%. But for a clear liquid we use to taunt our siblings, saliva is surprisingly versatile.
Saliva kicks off digestion in the mouth and it smoothens and moistens food so every bite doesn’t feel like sandpaper to your throat. It prevents tooth decay, mouth infection and contains calcium hydroxyapatite to prevent calcium loss from our teeth. It also serves as a mechanism to regulate our body water level. When water is low, our mouths and throats dry up and leave us feeling ‘thirsty’. And it helps us speak and taste food.
Saliva- what doesn't it do?
We have three major salivary glands, i.e. glands that produce and supply our mouths saliva. Ironically, only one of them is actually inside our mouths. The parotid glands are located just in front of our ears and secrete saliva through a small hidden passage-esque duct near our upper molars. The submandibular glands are below our jaws, and secrete saliva through a hatch-like duct beneath our tongues. And the smallest of them all are the sublingual glands, which are on either side of our tongues under the floor of our mouths, nothing special about them.
But like pretty much everything in our bodies, our saliva is controlled by our brains. That’s why your mouth dries up when you’re nervous or scared and just thinking about food can have your mouth preparing to digest it, but I won’t get into those details.
The thing about saliva is that almost every animal has it. From the mosquitoes to the snakes to the elephants to the birds and even to octopi. However, in a not so surprising twist, most fish, sharks and cetaceans (marine mammals) do not have salivary glands. I hesitate to say all marine animals because as previously mentioned, octopi have them. (I just realized I might need to tell you this, but octopi is the plural of octopus).
Anyways, variety is the spice of life and this proves itself if you observe all the ways different animals have adapted their saliva to suit them. Snakes turned a pair of salivary glands to venom glands for protection, vampire bats’ saliva contains an anticoagulant that prevents blood from clotting so they can feed (refer to previous article), the slow loris uses its saliva to activate a toxin secretion from a gland in its elbow and octopi saliva contains a substance that causes its prey’s muscles to relax so it can be eaten. Nature is terrifying.
That is it for today. I am out of things to say about saliva, which is a feat in and of itself. Please stay away from animals that you know nothing about, for your own safety. I hope you learned something or at least smiled once. Thank you for coming to my Ted talk.
