Tarantula preservation techniques and color retention / transformation

[Kada]

Who here likes to preserve specimens? I was wondering if we could discuss color retention of preserved tarantulas, by species.

Watching the Andrew Smith pokie documentary got me thinking about how people didnt realize P. metallica was blue due to specimen color.

Perhaps we can post pics and a short description of species, original color, any transformation and preservation style (eg. pinned, alcohol, formaldehyde dip etc) and see what looks like what before and after, then going through time

 

[AphonopelmaTX]

Firstly, anyone who didn't realize Poecilotheria metallica was blue didn't read the original species description published in 1900 by Reginald Pocock! The original description makes reference to the "metallic blue lustre" on its legs.

That aside, I'm not sure what there is to discuss when it comes to retaining the color of preserved dead of tarantulas. The method to use depends on what you want to do with it.

Fluid preservation in alcohol will destroy the colors, but it keeps the legs and body flexible for research. Color loss has been a big problem with academic researchers and with all of their resources haven't yet figured out how to solve it. Fortunately with today's imaging technology, publishing pictures of live or freshly preserved specimens makes up for it. And everyone has a high quality digital camera in their pockets these days so there shouldn't be an excuse for keeping a good record for us amateurs.

If the goal is to make a nice display out of your dead tarantula, and keeping the color is important, the only way to preserve the color is to pin and dry then mount in a shadow box. The major drawback is that the specimen will become hard as a rock or brittle making it impossible to examine later. But if you only want to make a display, then that is not important.

Forget about anything involving formaldehyde. That stuff is a highly toxic carcinogen and can only be obtained with a license. Your average Joe tarantula keeper won't be able to experiment with it.

 

[Kada]

Firstly, anyone who didn't realize Poecilotheria metallica was blue didn't read the original species description published in 1900 by Reginald Pocock! The original description makes reference to the "metallic blue lustre" on its legs.

Yes in text. I am just going by Smith's documentary on this one, because I sure couldnt go by experience decades past I am doubtful many did. The specimens preserved were not the lively blue we see today. Anyway, the idea for a discussion clearly isnt did we realize something was described, more about preserving aesthetics... Dead specimens, molts, peices and so on

That aside, I'm not sure what there is to discuss when it comes to retaining the color of preserved dead of tarantulas. The method to use depends on what you want to do with it.

Discuss experiences and results. Aesthetics.

Fluid preservation in alcohol will destroy the colors, but it keeps the legs and body flexible for research. Color loss has been a big problem with academic researchers and with all of their resources haven't yet figured out how to solve it. Fortunately with today's imaging technology, publishing pictures of live or freshly preserved specimens makes up for it. And everyone has a high quality digital camera in their pockets these days so there shouldn't be an excuse for keeping a good record for us amateurs.

Bingo, interested in a long for discussion on precisely this issue. It seems also precisely why people could see a blue P. metallica. regardless of academic trust, proper records dispelled doubts of older accounts. Worthy of discussion in my opinion.

If the goal is to make a nice display out of your dead tarantula, and keeping the color is important, the only way to preserve the color is to pin and dry then mount in a shadow box. The major drawback is that the specimen will become hard as a rock or brittle making it impossible to examine later. But if you only want to make a display, then that is not important.

Thus far, that has been my experience as well

Forget about anything involving formaldehyde. That stuff is a highly toxic carcinogen and can only be obtained with a license. Your average Joe tarantula keeper won't be able to experiment with it.

Without getting into safety, obvious is obvious. It is still common and the standard in most of the world. In many countries we have done field trips to, it is readily available in the cities. here, it is mail order and cheap. it is toxic as anything, sure, but I figure a groupz keeping venomous animals in their homes have the sense to research thoroughly. We still use it as a fixer for field collection of plants etc then dry/ switch out to another solvent for long term storage. Despite its nasty health effects, still seems SOP in a lot of places. always good to point out the health risks as well though. Aside from that, how does it act on tarantulas? My work is almost exclusively vertebrates so it varies quite a lot.


Photography is excellent, a game changer. As digital expands, so does the need for physical hard copies. that look true. no issue with multiple deposits of a single description in my opinion (ie. wet and pinned).

 

[klawfran3]

General preservation for soft bodied insects is 70% ETOH, while spiders are usually in 80% ETOH or Isopropyl. Same goes for scorpions and opilionids. Mites and ticks and pseudoscorpions are in 70% ETOH. Formaldehyde is being phased out due to the fact that it doesn't preserve genetic material well and it's way more dangerous than ethanol. Ethanol is cleaner, easier to store, easier to work with, and easier on the specimens. Formaldehyde also breaks down carotenoids faster and seems to bleach older specimens too.

Here's the issue with color preservation: structural coloration is made up of millions of microstructures that refract light and produce color. These tend to be your metallic bright colors, usually blues, pinks, and greens. Sometimes the animals use these in conjunction with pigment based colors, the main classes are carotenoids and melanins. An example of them used together is having a yellow carotenoid and a blue structural color to create green, or instead you can have just a green structural color.

Storing any specimen with structural coloration (eg. blues and greens) in ethanol will "destroy" the colors, as the ethanol has a different refractive index than air; it will fill the holes that cause the color and prevent them from refracting light properly. Once you take them out and let them dry off, however, the colors will reappear and look good as new. Structural coloration, as long as the physical structure isn't destroyed, will retain it's color permanently.

This isn't to say that structurally colored insects will remain as vibrant as when they died, however, since the body is full of fats and oils that degrade and break down, seeping out through the exoskeleton and clogging the structures. This is why older specimens have a brownish color to them, because all that grease has seeped out and coated the outside of the specimen. Soaking them in acetone for a few days (changing the bath regularly for larger ones) can help restore the color a bit.

For those specimens that use a mix of them (for example the blue structural and yellow carotenoids I mentioned earlier) their color will degrade over time as the carotenoid breaks down over time. No amount of acetone baths can bring this color back to the original since the actual physical pigment has broken down. You can get close if you clean the structure, but it will never properly return to the original.

When it comes to solely carotenoid or melanin based pigments, those are harder to preserve. They break down over time, and you cannot get them back. Blacks will degrade to brown, and yellows and reds will fade and look sickly.
A good example is Dendrobates leucomelas, the Bumblebee poison dart frog. When alive their bodies are vibrant yellow and pitch black, but the specimen that was described had been bleached by the formaldehyde and turned white and black, hence the name "leucomelas" which means "White and Black".

There isn't any good way to preserve these other than keep them out of UV and sunlight, and keep them far away from moisture as that can promote degradation even more. Regular baths in acetone can prevent the brown discoloration and make them look a little better too, but it's not a permanent solution. I know some museums that display specimens to the public will often repaint them to make them vibrant again (the May Natural History Museum in Colorado Springs is a great example of a huge collection over a hundred years old that does this. They're amazing. Go check them out in person. It's the best museum on earth.), but most research museums aren't going to do this since it ruins the scientific value of the animal since it's been altered.

I'm aware that boiling and temperature shocking some specimens like caterpillars can help preserve the green color they have, but this doesn't last forever and can also stain their ethanol too.

AFAIK, there isn't one good catch-all way to preserve colors for specimens. This is why we usually use species descriptions and their actual physical structures when describing them, since color is unreliable at best when preserved and even varies between individuals of the same species while alive.



On a personal note, I've been trying to track down the recipe for "KAA" which is a kerosene based preservative used by some museums for large soft bodied insects larvae like caterpillars. It's supposedly really good at preserving their colors and keeps specimens from shrivelling up like they took too cold a shower . There's one single book I know of that has the recipe, but it's not in print anymore and I don't have access to any college libraries where it might be stored. I can't find anyone that knows the recipe either, so this is my plead for anyone reading this to send it to me if you know it!!!

 

[l4nsky]

On a personal note, I've been trying to track down the recipe for "KAA" which is a kerosene based preservative used by some museums for large soft bodied insects larvae like caterpillars. It's supposedly really good at preserving their colors and keeps specimens from shrivelling up like they took too cold a shower . There's one single book I know of that has the recipe, but it's not in print anymore and I don't have access to any college libraries where it might be stored. I can't find anyone that knows the recipe either, so this is my plead for anyone reading this to send it to me if you know it!!!

The suggested preservative fluid is KAA (95% ethanol, 80–100 ml; glacial acetic acid, 20 ml; and kerosene, 10 ml)

https://www.sciencedirect.com/science/article/pii/S2090536X13000233

 

[klawfran3]

https://www.sciencedirect.com/science/article/pii/S2090536X13000233

Omg you're the best, thank you. I havent been able to find it anywhere. Time to mix up a big old batch and get to collecting again!

 

[l4nsky]

Omg you're the best, thank you. I havent been able to find it anywhere. Time to mix up a big old batch and get to collecting again!

Lol not a problem, just took 5 mins on Google .

Tangentially, is there a pro/con list for EtOH vs Isopropyl or is it more personal choice?

 

[klawfran3]

Lol not a problem, just took 5 mins on Google .

Tangentially, is there a pro/con list for EtOH vs Isopropyl or is it more personal choice?

Ethanol is the industry standard versus Isopropyl because isopropyl is more toxic and shrinks/ physically changes the specimen more. If you're gonna do DNA extraction then >95% ETOH is the only way to preserve the specimen, other than cryopreservation. Anything lower/other chemicals will destroy the DNA.

I used to work at a research museum for vertebrate zoology as their taxidermist, and I have my own insect collection that I've been super anal about maintaining properly for actual research. That museum thankfully gave me a whole heap of information and advice that I can bring over to the bug world haha.

Also I'm shocked it was that easy, I looked all over and wasn't able to find it. Maybe I'm just stupid? Lmao.

 

[l4nsky]

Also I'm shocked it was that easy, I looked all over and wasn't able to find it. Maybe I'm just stupid? Lmao.

Nah, just like you gathered your niche knowledge from an occupation, I've become quite proficient at finding and manipulating data because of my occupation (data analyst).

 

[Kada]

General preservation for soft bodied insects is 70% ETOH, while spiders are usually in 80% ETOH or Isopropyl. Same goes for scorpions and opilionids. Mites and ticks and pseudoscorpions are in 70% ETOH. Formaldehyde is being phased out due to the fact that it doesn't preserve genetic material well and it's way more dangerous than ethanol. Ethanol is cleaner, easier to store, easier to work with, and easier on the specimens. Formaldehyde also breaks down carotenoids faster and seems to bleach older specimens too.

Here's the issue with color preservation: structural coloration is made up of millions of microstructures that refract light and produce color. These tend to be your metallic bright colors, usually blues, pinks, and greens. Sometimes the animals use these in conjunction with pigment based colors, the main classes are carotenoids and melanins. An example of them used together is having a yellow carotenoid and a blue structural color to create green, or instead you can have just a green structural color.

Storing any specimen with structural coloration (eg. blues and greens) in ethanol will "destroy" the colors, as the ethanol has a different refractive index than air; it will fill the holes that cause the color and prevent them from refracting light properly. Once you take them out and let them dry off, however, the colors will reappear and look good as new. Structural coloration, as long as the physical structure isn't destroyed, will retain it's color permanently.

This isn't to say that structurally colored insects will remain as vibrant as when they died, however, since the body is full of fats and oils that degrade and break down, seeping out through the exoskeleton and clogging the structures. This is why older specimens have a brownish color to them, because all that grease has seeped out and coated the outside of the specimen. Soaking them in acetone for a few days (changing the bath regularly for larger ones) can help restore the color a bit.

For those specimens that use a mix of them (for example the blue structural and yellow carotenoids I mentioned earlier) their color will degrade over time as the carotenoid breaks down over time. No amount of acetone baths can bring this color back to the original since the actual physical pigment has broken down. You can get close if you clean the structure, but it will never properly return to the original.

When it comes to solely carotenoid or melanin based pigments, those are harder to preserve. They break down over time, and you cannot get them back. Blacks will degrade to brown, and yellows and reds will fade and look sickly.
A good example is Dendrobates leucomelas, the Bumblebee poison dart frog. When alive their bodies are vibrant yellow and pitch black, but the specimen that was described had been bleached by the formaldehyde and turned white and black, hence the name "leucomelas" which means "White and Black".

There isn't any good way to preserve these other than keep them out of UV and sunlight, and keep them far away from moisture as that can promote degradation even more. Regular baths in acetone can prevent the brown discoloration and make them look a little better too, but it's not a permanent solution. I know some museums that display specimens to the public will often repaint them to make them vibrant again (the May Natural History Museum in Colorado Springs is a great example of a huge collection over a hundred years old that does this. They're amazing. Go check them out in person. It's the best museum on earth.), but most research museums aren't going to do this since it ruins the scientific value of the animal since it's been altered.

I'm aware that boiling and temperature shocking some specimens like caterpillars can help preserve the green color they have, but this doesn't last forever and can also stain their ethanol too.

AFAIK, there isn't one good catch-all way to preserve colors for specimens. This is why we usually use species descriptions and their actual physical structures when describing them, since color is unreliable at best when preserved and even varies between individuals of the same species while alive.



On a personal note, I've been trying to track down the recipe for "KAA" which is a kerosene based preservative used by some museums for large soft bodied insects larvae like caterpillars. It's supposedly really good at preserving their colors and keeps specimens from shrivelling up like they took too cold a shower . There's one single book I know of that has the recipe, but it's not in print anymore and I don't have access to any college libraries where it might be stored. I can't find anyone that knows the recipe either, so this is my plead for anyone reading this to send it to me if you know it!!!

That is fantastic information, thanks so much for taking the time. Jewel of a post.


my previous experience with formaldehyde and formalin are strictly as fixatives. the idea being then, fix the subject then swap out to alcohol for long term storage. Obviously I have no experience in regards to tarantulas thus the thread hehe

My concern was also with such color structures as you noted, as an example let's say P. metallica. You noted acetone, is there any benefit/detriment to also soaking first, to extract some/bulk of the oils out first after a few washes? This may require an incision in the rumpfor greater surface area and penetration?

on the other more pigment related preservation, do you know anything on EMA? I have only just read about it as an alternative to formalin. And the ingredients are all fairly same and easy to get reagent grade with far easier disposal logistics

Tried to google the names of the body parts responsible for reflecting light, came across this article. Super fascinating!

The evolution of coloration and opsins in tarantulas - PubMed

Tarantulas paradoxically exhibit a diverse palette of vivid coloration despite their crepuscular to nocturnal habits. The evolutionary origin and maintenance of these colours remains mysterious. In this study, we reconstructed the ancestral states of both blue and green coloration in tarantula...

pubmed.ncbi.nlm.nih.gov

As an aside, when live specimens are frozen/thawed, could perhaps cause any damage with the shrinkglage/expansion and possible causing more brittle flesh? My plan is to ask breeders to send me dead specimens frozen through the mail.

Could perhaps sending specimens in frozen storage but in sollution perhaps be a better route? They cna easily be wrapped in jars to avoid splashing around.

 

[vitrumaranea]

Oxford invertebrates: Walker,Fitton, Vane-Wright. and Carter love their ultrasonic sparger for cleaning and fluid purging. It has also received good color retention reports in resin fixing as it clears the oxygen bubbles stored in spider hairs that cause yellowing. The hobbyist can pick one up for about $150