Snake Anatomy and Biology - The Wildlife Center of Virginia

Wildlife Classroom Series: Snake Anatomy and Biology Page 1

Wildlife Classroom Series: Snake Anatomy and Biology

Wednesday, February 13, 2013 Raina Krasner, WCV: So everyone is ready to learn some really interesting snake facts? Comment: Got my lunch here and ready to learn! Comment: I'm late, I'm Late!! So sorry. We can start now~ Comment: Yes. Lets go Comment: Raina, hi and does Year of Snake include Rattlesnakes & poisonous ones? Raina Krasner, WCV: Of course it does! Venomous snakes are still snakes. Comment: Rats. I will heat my lunch too. Comment: Happy New Year! Even the hawk is joining in! :) Comment: Yes please enlighten me....I have never been a snake fan. Comment: ALL snakes ALL the times. Comment: Mrs. Price's class in Illinois is here. We adopted Severus and we want to learn more about snakes. Raina Krasner, WCV: Hello Mrs. Price and students!


Raina Krasner, WCV: You're in for a treat...we have some fun Severus photos coming up. Comment: Oh Hi Mrs Price and class. (Nice name!) Comment: Oh, I love Severus. He is big now. Raina Krasner, WCV: He is big! Comment: Shouts of Hooray!! Raina Krasner, WCV: Ok, so let's get started. Raina Krasner, WCV: We are kicking of our Wildlife Center Classroom Series with a discussion of snake biology and anatomy. This is also marks the start of our Year of the Snake celebration. Yay! For more information on the Year of the Snake visit our website. http://wildlifecenter.org/news_events/news/year-snake Raina Krasner, WCV: So let’s begin by answering a simple question: what is a snake?

Malcolm the Education Cornsnake


Raina Krasner, WCV: To answer it simply, a snake is a legless, carnivorous, reptile. Today we will discuss their biology more in-depth, but that is the [very] simple definition. Raina Krasner, WCV: That lovely snake specimen is one of our Education snakes...Malcolm the Cornsnake. Raina Krasner, WCV: Many people think that because snakes have no limbs, they are just one, long body part – not true! Raina Krasner, WCV: A snake’s skeleton can easily be divided into a head and neck portion, a torso, and a tail. Comment: He's beautiful! I've never seen on in the wild..what kind of habitat are cornsnakes found in? cornfields? Raina Krasner, WCV: Good guess! They can certainly be found in cornfields...but not because there is corn. As I just mentioned, snakes are carnivorous. Which means they only eat meat. Raina Krasner, WCV: So snake skeletons...Yes, I said skeleton! Snakes are vertebrates, which means they DO have a spine and a skull and ribs. They’re not like our invertebrate – earthworm friends, although many people mistakenly compare snakes to worms. They are quite different! Raina Krasner, WCV: In fact, snakes are kind of like super-vertebrates. They can have several hundred individual vertebrae in their spine, compared to just 33 in a human spine. The large number of vertebrae helps the snake bend more easily and at greater angles. Comment: do u have a xray for the snake Comment: Do you have a picture of the snake skeleton?

2013 Radiographs of Severus the Education Eastern Ratsnake


Raina Krasner, WCV: There you go! Here is a portion of Severus’s radiographs (one of our education snakes). You can see his spine and ribs here. Raina Krasner, WCV: And this is one of the 4 radiograph slides that were needed to get an image of Severus's full body...since he's over 65 inches long. Comment: Wow! That's a lot of ribs!! Cool! Comment: Good afternoon Raina. Is the snake skeleton made of bone or cartilage? Raina Krasner, WCV: Bone. Raina Krasner, WCV: All those ribs protect the organs that are spread along the snake’s body. Raina Krasner, WCV: Imagine we laid a snake out on a table... Here is what it would look like if that snake was cut open (as if we were doing a necropsy – an examination of a dead animal).

Snake Anatomy Diagram


Raina Krasner, WCV: The first portion of the snake’s body – think of it like the first quarter of the snake – contains the head, the esophagus (for swallowing food), the trachea (for breathing), and the heart. Raina Krasner, WCV: And the head contains the brain, the eyes, the nostrils and the mouth (later, we’ll learn more about the structure of a snake’s mouth). Comment: no heart??? pretty cool Raina Krasner, WCV: The heart is there, too! Comment: have to look for it then Raina Krasner, WCV: See where it says "right atrium" and "left atrium"? That's in reference to the heart. Raina Krasner, WCV: The second quarter of the snake’s body contains part of the lungs, the liver, and the stomach. Comment: Sorry to ask this dumb question but do snakes breath with lungs like other animals I have never seen one breath but to be honest have never stayed long enough to see it. Raina Krasner, WCV: They do breathe with lungs, but they breathe a bit differently than we do. Raina Krasner, WCV: They lack a diaphragm, the muscle that we have that helps us breath. Instead, muscles connected to the snakes’ ribs are expanded and contracted to push air in and out of the lung(s). Raina Krasner, WCV: Some species of snakes have two lungs, while some only have one (usually along with a small left lung). Raina Krasner, WCV: In those species, the left lung would be found in the third quarter of the snakes' body. Raina Krasner, WCV: The third quarter also contains the gall bladder, the spleen, and the pancreas. Comment: The spleen is pretty small compared to other animals! Is that common in reptiles in general? Raina Krasner, WCV: I'm not sure if that's common throughout all reptiles. But in some species of snake, the spleen and pancreas are combined as a splenopancreas.


Comment: Neat! Raina Krasner, WCV: Below that cluster of organs are the gonads – the testes in male snakes and the ovaries in female snakes. Raina Krasner, WCV: And the small intestines. Raina Krasner, WCV: The last, and final, quarter of the snake’s body, contains the junction between the small and large intestines, the kidneys, and the cloaca. Raina Krasner, WCV: The cloaca serves several purposes. Raina Krasner, WCV: Merriam Webster dictionary defines the cloaca as “a chamber into which the intestinal, urinary, and reproductive canals empty”. Basically, it’s the opening through which snakes defecate, urinate and give birth (by laying eggs or live birth). Comment: Wow! snakes have a lot of the same organs that we have!! Comment: Very interesting. I have been around snakes but didn't consider how their organs were spaced Comment: This is so amazing......they have the same organs we do! Don't know what I thought was inside of them. :-) Raina Krasner, WCV: Right! They really aren't so different. Raina Krasner, WCV: Well, they are different from us in one pretty big way. Raina Krasner, WCV: They don't have limbs! And since they don’t have limbs they move a lot differently than we do. They use their very strong muscles along the length of their body to help them move. They also rely on special scales called “scutes” on the underside of their body to help move them along the ground. Comment: arms?? cold blooded?? Comment: they shed their entire skin??? Raina Krasner, WCV: Ok…so there is more than one way they are different from us. :) Comment: wehave the same basic internal body plan?


Raina Krasner, WCV: We have many of the same organs, but snakes have everything spread out. Because they're like a big tube. Comment: Birds also have cloacas, don't they? is that because of evolutionary relationship between reptiles and birds? Raina Krasner, WCV: They do. I'm not sure about the evolutionary significance, but they have cloacas that act in the same way as birds. Raina Krasner, WCV: So, what protects all of these bones and muscles and other organs? Comment: snakeskin! Comment: Skin! Comment: Thick skin?? Comment: well, for us, the skin protects everything - so their skin? Raina Krasner, WCV: Ding ding ding! Raina Krasner, WCV: The biggest organ of all – skin! Raina Krasner, WCV: There is a pretty big misconception about snake skin. Snakes are NOT slimy. In fact, their skin is quite smooth and dry. Comment: Interesting that the skin is called and organ - but I guess that it lives, breathes and grows. Comment: Well, an organ is a collection of tissues. :) Raina Krasner, WCV: Snakes are covered in scales made from keratin (the same stuff that makes our fingernails). The scales on the top portion of the snake’s body are smaller and are somewhat of a diamond shape. The scales underneath – the scutes – are like vertical bars.


Eastern Ratsnake snake skin shed

Comment: Those tissues work together for a 'common goal' and thus form our bodies' first line of defense! Raina Krasner, WCV: Right! Raina Krasner, WCV: These scales are connected by soft skin that can stretch and expand. The scales are hard and not stretchy, so the skin between the scales plays an important role in allowing the snake’s body to expand and contract (like after they have a big meal!) Comment: I shed my skin....a little at a time! Doesn't every mammal? Not as dramatic as the snake, though! lol Comment: I'm glad humans don't shed their skins! Yuck! Raina Krasner, WCV: We do! Everyone sheds skin. But snakes do it...in a more dramatic way. I think that's a great way to put it, egghead. Raina Krasner, WCV: But remember, snakes aren't mammals like us. They are reptiles.


Comment: That snakeskin photo is awesome! Such detail Raina Krasner, WCV: (I took it with my iPhone, believe it or not!) Raina Krasner, WCV: It's a detail of this snake skin:

Tiny Dr. Dana next to Severus's shed!

Raina Krasner, WCV: That's our vet intern Dr. Dana Tedesco holding the shed of Severus, our largest education snake. He measures in at least 65 inches. Comment: Oh WOW! He is big. Comment: Servus is a BIG boy!! Comment: cool picture of the skin shed


Comment: I guess I should rephrase my comment, I'm glad humans don't shed their entire skin all at once! Jeez what would you do with it afterward? LOL Raina Krasner, WCV: It would be...weird. Especially because of what happens when snakes shed their skin. Raina Krasner, WCV: As snakes prepare to shed their skin (officially called ecdysis), a milky-blue fluid helps to separate the dead layer of skin from the skin underneath. This gives the snake a milky-blue, dull appearance. Raina Krasner, WCV: The snakes eyes also turn a bluish color. Snakes do not have eyelids, but instead have “spectacles” – a layer of skin that covers the eyes. The spectacles on each eye are shed along with the rest of the skin.

Severus with milky spectacles

Raina Krasner, WCV: He looks like he's blind, but really he's just getting ready to shed! Comment: That so cool about the scutes being connected by flexible skin...i've looked at the shed skin of my resident blacksnake, but i guess never examined it that carefully...or didn't really know what i was looking at! Comment: that snake is big...wow Comment: Is the snake skin ever broken during the shedding, or does it come off in one complete piece?


Raina Krasner, WCV: Sometimes it comes off in pieces, but if the snake is shedding in good conditions (the right amount of moisture and something rough to rub against) then it can come off in one big piece, like that big one did! Comment: So, they look like that picture when they are beginning to shed their skin?? Raina Krasner, WCV: Yes. Comment: Help my confusion, is it just the "skin" that is shed, like top layer when we have sunburn, or scales as well? How does that work? Raina Krasner, WCV: It's the top layer of skin. So the skin organ remains intact. But its the scales AND the skin that connects the scales. Comment: How long would it take a snake the size of Severus to shed its complete skin? from start to finish? Raina Krasner, WCV: Funny story actually... Raina Krasner, WCV: I took Severus out for a program, and he was acting very grumpy (they can get a little aggitated as they are about the shed) and I couldn't figure out why. I went to take him OUT of the box later, and there was that giant shed! Raina Krasner, WCV: So, that was just a few hours. Raina Krasner, WCV: They start by breaking the skin on their face at the nose and peeling it off by rubbing against things. Comment: Raina, what determines when it sheds. Raina Krasner, WCV: Snakes shed a lot more when they are younger, as they are gorwing quickly. But, they will keep growing throughout their lives and will shed several times a year. Some more than others. Comment: The milky eye looks like cataracts! Raina Krasner, WCV: They do! But he's not blind. His eye is just covered by the milky fluid that's helping to separate the old skin layer. Raina Krasner, WCV: But speaking of eyesight...


Raina Krasner, WCV: Snakes have fairly poor eyesight. At the very least, they are not believed to see color and shapes are likely not well-defined. Raina Krasner, WCV: They also have relatively poor hearing. They can detect low frequency sounds but have a very limited range of what they can hear. Raina Krasner, WCV: They lack an outer ear (like the ear lobe in humans), but their inner ear allows them to detect motion and sound waves that travel through the ground. Raina Krasner, WCV: And because they have relatively poor vision and poor hearing, most snakes primarily rely more on their sense of smell. Raina Krasner, WCV: They do have nostrils, but their nostrils are used for breathing, not smelling. Raina Krasner, WCV: Snakes use something else to smell...

Cornelius the Education Cornsnake.

Raina Krasner, WCV: Any guesses? Comment: tongue Comment: tongue Comment: Tongue!


Comment: tongue Comment: tongue! Comment: Their tounge. Raina Krasner, WCV: Correct! Such snake savvy people we have today. Raina Krasner, WCV: Snakes have forked tongues. Two pronged. The two prongs allow them to better detect from which direction a scent is coming. Raina Krasner, WCV: You can see the forked tongue in that picture of Cornelius. Comment: Geez, finally something I remembered from my school years! Comment: oh yes! their tongues! and do they have a Jacobson's organ like cats? Raina Krasner, WCV: Yes! Raina Krasner, WCV: A snake sticks out its tongue into the air and flicks it around, catching scent particles in the air. It then retracts its tongue into its mouth against ducts that lead to the sensory structure known as the vomeronasal organ or the Jacobson’s organ. The organ processes the scents and transmits the information to the brain. Comment: what's that? Raina Krasner, WCV: The Jacobson's Organ? Well, here is a helpful photo.

Reptiles Alive! shows us where the Jacobson's Organ is located.


Comment: I had no idea Comment: Hummmm, I had forgotten that. Good info. Raina Krasner, WCV: For most snakes, their sense of smell in primarily how they find their food. As we mentioned earlier, snakes are carnivorous reptiles – they only eat meat. Comment: Is that like taste buds. Raina Krasner, WCV: No, they don't taste with their tongue. Just smell. Comment: What kind of snake is this? Very bright. Raina Krasner, WCV: I believe that's a non-native boa of some sort. I got this picture from Reptiles Alive! Comment: They are amazing creatures. The more I learn, the more amazed I am. Raina Krasner, WCV: Another fun fact: Raina Krasner, WCV: Some snakes [such as rattlesnakes, copperheads and Cottonmouths] have a heat sensing pit that allows them to “see” heat. This sensitive infrared-sensing organ is located between the eyes and the nostrils, and it allows them see heat emitted by potential prey. It’s an additional tool these species of snakes have for hunting.

Copperhead snake


Raina Krasner, WCV: If you expand this photo of a Copperhead, I've circled the "pit". Comment: Is that why they are called pit vipers? Comment: What pretty skin he has! Raina Krasner, WCV: Yes, they have really interesting patterns. Comment: Cool! Er...maybe hot! Raina Krasner, WCV: Speaking of heat... Raina Krasner, WCV: Snakes are not hot. Raina Krasner, WCV: Well, they're "cold-blooded". Raina Krasner, WCV: Which is a not-so-technical name for "ectothermic" Comment: Need the sun to warm them up. Raina Krasner, WCV: Right! Raina Krasner, WCV: This doesn’t mean that their blood is cold. It means that snakes cannot regulate their own body temperature and rely on their environment to cool them off or warm them up. Raina Krasner, WCV: Which is why you might sometimes find a snake basking in the sun to warm himself up. Or hiding under log, out of the sun, on a particularly warm day. Comment: heat lamp Raina Krasner, WCV: Correct. And that's why we use heat lamps for our captive snakes. Comment: They love my asphalt driveway as a warming spot.


Raina Krasner, WCV: Great place for snakes! As long as they don't get run over. Comment: They have heat lamps and their pens get misted to provide humidity at WCV. Comment: But not asphalt in Texas TOO Hot!! Raina Krasner, WCV: That could be bad! Comment: LOL! I learned about that infrared heat "sensor" capability of certain snakes due to Trivia ? posters questions. I had to look it up to try to answer! Raina Krasner, WCV: It's a neat snake fact! Comment: Climbing the Blue Hills in my part of Mass, I surprised a snake "basking" in the sun, and made record time down the hill!! Comment: Are some or all snakes protected by law here in Virginia? I have friends who think that when they find a snake basking on their driveway, the thing to do is beat it to death with a shovel, which always drives me nuts. Raina Krasner, WCV: Yes. Snakes are protected by law in Virginia. Raina Krasner, WCV: You cannot kill them unless they are an IMMEDIATE threat. Comment: That's good to know, thanks! Raina Krasner, WCV: Under Virginia law, snakes are classified as a non-game species and are afforded protection under non-game regulations. While killing snakes is not a permitted activity, they can be taken (along with certain other species of wildlife) when classified as a "Nuisance species" (29.1-100); when found committing or about to commit depredation upon agricultural or property damage, or when concentrated in numbers and manners to constitute a health hazard or other nuisance. Raina Krasner, WCV: From the Virginia DGIF. Raina Krasner, WCV: So those snakes should be able to rest easy on your neighbor's driveway. Raina Krasner, WCV: Although, you likely won't see too many snakes out at this time of year.


Raina Krasner, WCV: Because snakes are so easily affected by the temperature of their environment, in the colder months, snakes enter a form of hibernation (some reptile people refer to this as brumation, but both words are acceptable) Raina Krasner, WCV: Right now, the Wildlife Center isn’t receiving many reptilian patients. They will remain in hibernation until the weather becomes warmer. Raina Krasner, WCV: So even though we don't have any new snake patients... Raina Krasner, WCV: ...we do have something else new...

Albus the Eastern Ratsnake

Raina Krasner, WCV: Meet our newest Education snake, Albus! Amanda Nicholson, WCV: Ack! He's so cute! Raina Krasner, WCV: I know! I can't stand it. Comment: GREAT name for a snake -- can he be friends with Severus, another great name - ? Raina Krasner, WCV: Yup. We've been introducing them, and they seem to be getting along well. Comment: He's precious.

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Comment: AWESOME!! Amanda Nicholson, WCV: I love him! How can you not love that face?? Comment: he's gorgeous! Comment From Randy @ Wildlife Center Wow, that's a small snake. Raina Krasner, WCV: He's smaller than Severus, yes. But still pretty big! Raina Krasner, WCV: We haven't measured him yet. Comment: why can't he be released? ( i could look it up but am working and lurking) Raina Krasner, WCV: http://wildlifecenter.org/critter-corner/current-patients/albus Comment: So cute - you can see the tip of the tongue sticking out! Comment: AH! Albus and Severus. Harry Potter theme reigns! I love it! Comment: What type of snake is Albus? Raina Krasner, WCV: An Eastern Ratsnake. Formerly known as Black Ratsnakes. Raina Krasner, WCV: He's the same species as Severus, one of our other education snakes. Comment: what happen to him Raina Krasner, WCV: He was an illegal pet. Raina Krasner, WCV: And the person was no longer able to keep him.


Comment: Aw, poor fella. Does anyone have any clue if snakes get stressed and freaked out over being "re-homed" like, say, dogs and cats do? Raina Krasner, WCV: i'm sure there is an adjustment period, but we do our best to make it a smooth transition. Comment: Albus is sooo cute! He even looks like he is smiling! (Can you tell I love snakes?) Raina Krasner, WCV: Good!!! So who else is starting to warm up to snakes after today? i know some people joined us that were already on the snake bandwagon. But is there anyone who's having a change of heart? :) Comment: My heart is changing a little. Thanks for opening my eyes. This has been great. Comment: I think snakes are interesting Comment: i guess me it will take a little time but i will like snakes Comment: Count me in! Even though my late husband was bitten by a copperhead and nearly died. But if you step on one like he did, a snake will react. Duh! Comment: My hand is raised, Raina. I've found that I love many critters, (snakes & spiders!) that I ran from, before. Nobody's talked me into loving Slugs yet though!! lol Comment: I'm on good terms with whichever snake passes through my yard but we each give the other a wide berth. I don't get close enough to identify but I don't run either. Comment: sorry forgot to type my name i guess me i will get use to it Comment: i was already on the bandwagon, glad to see some others "coming around"! Comment: I am not going to go out and hug one but I guess I can live with them Raina Krasner, WCV: Ah...well that's all we're asking! Comment: Have to admit, snakes are starting to look better. Thanks Raina! This was a fun and very informative class. Can't wait til the next one!!


Comment: You have made me look at them differently...but I am still going to give them their space! :o) Comment: Never been wild about snakes, as in, I have no desire to have one, but I think they are fascinating and should be respected like all other creatures. Amanda Nicholson, WCV: Well, I think our goal here (at least my greatest hope) is that if we can't convince you that snakes are amazing and wonderful ... if we can't convince you to LIKE them ... we will definitely settle with just acknowledging they are a valuable part of the ecosystem. You don't have to like them, just give them a bit of respect, and don't do that "kill first, ask questions later" thing. Comment: Raina, what can we do to help snakes? What are your suggestions? Raina Krasner, WCV: I think one of the best things you can do is learn about them, learn to respect their importance in our ecosystem, and share appreciation of snakes with others! Amanda Nicholson, WCV: And maybe you can grow to respect them ... love them! ... by adopting Albus through the Caring for Critters program. :) (he has such a cute face!)

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Snake Anatomy and Biology - The Wildlife Center of Virginia