Storage of Embalmed Specimens

STORAGE OF EMBLEMD SPECIME NS

More than 11 million fluid specimens, including Bonnethead sharks and bigel Komodo dragons, are housed in the basement of the Field Museum in Chicago. Here, there are 883 frogs. However, why keep them all and keep them wet? Imagine it as a library. Wet species, various shapes, and in some circumstances even DNA are stored in this fashion. The closest thing to having a living zoo in a lab that researchers can achieve. Each jar is a book that researchers can open and study, occasionally finding entirely new species right here.

You can't easily throw a Komodo dragon into a tank of vodka, but they are available on the market. It is necessary for the field museum to obtain and diligently prepare them so The field museum obtains its specimens in two ways: either through donations or occasionally researchers go out into the field to deliberately euthanize specimens like this common water snake, which will bite you if you manage to catch one. Since DNA wasn't actually used in the manner it is now until the 1990s, this is a relatively recent step in the process, but Sarah's research relies on both new and old specimens to determine how changes in environment have impacted the species over time.

However, it is considerably simpler to obtain high-quality results when tissue samples are taken from live animals as opposed to those that have been stored. Since it gets so hot, I have to dip the scissors and forceps she uses to collect the DNA sample into some ethanol so that it doesn't effectively sear the animal while I work on it. She uses scissors and forceps to collect the DNA sample, first sterilizing them by burning away any random DNA so the findings aren't jumbled. In order to preserve the snake's outside appearance, Sarah collects the sample from within the snake.

The liver is right there; it's Sarah's favorite tissue to collect for DNA extraction because it dissolves easily, turns everything pink, and says sr1291. I'm cutting this way so that if anyone comes along they can still count these scales, and that's also where the liver is. I confirm that my tag is SR1291, and when the DNA is placed in these enormous liquid nitrogen freezers with thousands of other DNA samples, the specimen is prepared for formalin, which protects the tissue and keeps it stable. Stuck in time Sarah will pose the snake so that you can see the visible penises from outside the jar without even opening it. In this pose, the snake will remain for the rest of its afterlife the coil does.

It's kind of like embalming it just like a person at a funeral home Sarah has to keep in mind what information she needs now and what researchers might need in the future like the sex of the snake it's always good to see if maybe if it's a male snake if one to three four with each other in a jar. The final step in this process is tucking it in under a formalin and soaked paper towel to keep the snake saturated without having to fill the tub good night snakey over a few days the formalin will set into the tissue leaving the snake fixed in place almost like you're holding a rubber snake. Larger animals might need more than a few injections like this catfish. I have five snakes here and there are probably another six in this jar.

Caleb is working on calculating the amount of formula needed is mostly based on experience and feel too little and your specimen will start to decay and get floppy too much and your specimen will bloat and become disfigured you don't want to like make the belly do this because you've pumped it with so much formalin you don't want to like make the belly do this because you've pumped it with so much formalin once Caleb is confident his catfish is sufficiently full he'll move Especially with large specimens, which will release a lot of debris and fatty oils that were stored in their bodies and will leach out into the ethanol, which causes a lot of the discoloration, but still doing its job in keeping the animal preserve, alcohol is less toxic than formalin, making it safer for researchers in the long run. The specimen doesn't change much while it sits in its final resting tank just the color of the liquid.

The first step is to dye the specimen blue since little bones are hard to keep track of, so instead of separating the skeleton, this procedure keeps it contained but visible inside the body. The red dye is applied to the bones after the fish has been cleared using an enzyme called trypsin, which breaks down proteins but leaves the collagen that holds everything together intact, making the fish completely transparent. One benefit of clearing the fish first and then dipping it in the red dye is that you can keep the fish for a longer period of time.Because glycerin and collagen have the same refractive index, or the way that light passes through them, the entire process can take anywhere from a few days to about a month when done correctly, and the result is these almost alien-looking specimens that are stored in glycerin so researchers can access them when they only want to see bones and cartilage.

These two fish species are identical on the outside, but when you clear and stain them and look at their bones, you can actually see that there are differences in their skeletons between species. New species can hide on the shelves for decades. You can put this under a microscope. You can move bones around and see how one bone moving affects other bones nearby. Entire new species have been discovered this way.Here we go like this spider-tailed horned viper kept under lock and key. It was originally collected in the 1960s, and researchers initially believed it to be a different species of viper with an abnormality, such as a weird weird parasite or a tumor, but then in the early 2000s some herpetologists came along and said you know I think it's a whole new species altogether once a second one was found they compared it to this one and the species pseudo-seracity is.

There is even a field in the database for noting when and where a specimen was last seen so that if someone asks for it we know that well at least at this date it was spotted on the Shelf in the collection and once you find it it's not always as simple as pulling a jar off a shelf. Different families of fishes have numbers and then within each family they are arranged alphabetically by genus and then by species.

There are 883 frogs in this collection, and each one has a unique ID number, so if a researcher wants to examine a particular frog, I have to sit down and pick each one up one by one, saying, "No, not this one, not this one," until they find the correct one. The frogs were previously stored separately, but occasionally, when space was at a premium, they were combined with jars of the same species but collected by different people from different locations as I've previously stated that selling things is not an option. The oldest specimen in our collection of amphibians and reptiles is proof positive that old specimens can be exceptionally important.

It can be hit or miss; the success rate can range from zero percent to as high as maybe 60 or 70% if all you have is a 100-year-old snake in them. Sarah has even developed a technique for covering DNA stuck inside them. The process is similar to getting DNA from fresh tissue with a little extra work that includes heating it up really high and trying to digest it and pull the DNA away from the formalin over a much longer period of time. Like with library literature, you might as well try it. Some of these jars can remain unopened on their shelf for years until someone with curiosity opens them. Our view of the natural world can entirely change with just one open door, I always think, whether it's DNA or preserving the entire specimen so that it doesn't just perish in vain but instead lives on in science forever.