Snakes! A little creepy, but very cool!

Wow!  We dissected snakes!  Most were pretty long, around 2-3.5 feet or so.  There was one that was very small, and my guess was that we ordered so many they didn't have enough large ones so they took a younger, smaller one.  We were disappointed about not being able to see any animals inside the stomachs of our snakes.  I guess they didn't feed them before sacrificing them.  But we did learn a lot!

The snake is in class Reptilia, which is a group of animals well adapted to live on land.  We noticed the differences between the scales on the bottom of the snake compared to those on top, and saw that the eyes are covered with scale, not a thin membrane like the frog's eyes.  We thought it was cool that each scute, which is a scale on the ventral side of the snake, corresponds to a rib in the snake!

It took us a while to find the tongue of the snake, it is tiny and black and forked.  It is a sense organ for smell, and it tastes things in the air, then puts them on the roof of its mouth where Jacobson's organ sends information about the molecules to the brain.  The snake does not have ears, but detects vibrations in the ground through ossicles, which are ear bones.

Snakes have two nares (basically like nostrils) on their snouts, and two inside their mouth, and that's how they breathe.  It turns out they generally have one big long lung going along their bodies, and also a second very small one that doesn't function.  Of course all the organs of the snake need to be long and thin to fit in their bodies, so the hear, liver, and kidneys are also like that.  There is a lot of fatty tissue in the snake, we figured to keep their bodies warm when it gets cold.

Like the frog, the snake's heart has three chambers and the blood mixes in the ventricle.  This is different from how our heart works.  We'll see with the next dissection how a mammalian heart is organized.

Research article:  This week's research article was about how snake venom does what it does.  We discussed that snake venom is not a poison because eating it is not dangerous.  But when it gets in an animal's bloodstream, it does several things.  For one thing, it has specific proteins in the venom that prevent the blood from clotting, so that the other proteins in the venom can attack the entire animal.    The other proteins often do things like block the signal from the nerves to the muscles, but they can also attack and kill red blood cells.  The article I discussed was "The collagen-binding integrin a2b1 is a novel interaction partner of the T. flavoviridis venom protein flavocetin-A".  They found that a specific venom protein called flavocetin-A sticks very tightly to a protein called integrin a2b1 as a way of blocking blood clotting, and this could be a helpful piece of information for developing new drug treatments for medical purposes.

Review from last week:  We didn't have time to discuss frog research last week, so I shared this article about tadpoles and how they respond to parasites and predators.  I also mentioned this article which explored how tadpoles start to get bulgy and fat after coming in contact with predatory salamanders.  Weird!  This image shows a regular tadpole on the left, and the bulgy morph on the right.