15 of the wildest animal specimens I saw hidden underneath one of the world's largest natural history museums

I've visited the Field Museum for 21 years and finally got to tour one of its hidden collections.
Researchers preserve and store 11 million wet specimens in the basement.
Here are some of the most valuable, impressive, and odd specimens of the bunch.

The Field Museum in Chicago is home to around 40 million specimens and artifacts — but only 1% are on display. Business Insider USA

I've been visiting the museum since I was 9 years old, but I've never seen its hidden collection of 11 million wet specimens until now. Business Insider USA

It's primarily scientists allowed to access the collection, so it was a real treat to browse the stacks of odd animals as a visitor. Business Insider USA

Researchers embalm animals and store them in ethanol for future research. It's the closest they can get to keep a living zoo on hand. Business Insider USA

Since wet specimens are kept in highly-flammable alcohol, the ceiling over the collection is explosion resistant to protect the museum. Business Insider USA

An ideal alcohol ratio of 70% keeps specimens as true to life for as long as possible. This shielded worm lizard is almost 200 years old and hasn't changed much. Business Insider USA

I got the chance to see Assistant Collections Manager Josh Mata add a new specimen to the collection — a female Komodo dragon. Business Insider USA

It takes weeks to prepare a large Komodo dragon. She joined two other female dragons in a custom-made tank filled with alcohol. Business Insider USA

Over time, leaching debris and fatty oils from the specimen turn the alcohol amber, but the color doesn't affect the quality. Business Insider USA

Chinese and Japanese giant salamanders fill another tank. Thanks to the salamanders' genus, andrias, Mata calls this extra smiley one "Andre." Business Insider USA

This hammerhead bat's huge nose makes it perfect for wet preservation. If its skin dried out, it would be much more difficult to study its schnoz. Business Insider USA

Most specimens in the wet collection are kept looking as life-like as possible, but these altered fish serve a specific purpose. Business Insider USA

When researchers want to look at the skeleton of small fish, they'll clear the tissue and dye its cartilage and bones, a process called diaphonization. Business Insider USA

Many specimens are one-of-a-kind. This endangered Ryukyu black-breasted leaf turtle is alone in the collection; the museum will probably never get another. Business Insider USA

The coelacanth is more closely related to humans than it is to most other fish. Scientists thought it went extinct 66 million years ago, but the species was discovered very much alive in 1938. Business Insider USA

Even abundant specimens like common water snakes have some interesting features. Those pale pink lumps are the snake's two penises and have been preserved for easy identification. Business Insider USA

And if species-specific collections get too big, the museum might consolidate them. You're looking at 883 frogs, all in one tank. Business Insider USA

When researchers want to study a specific frog, they have to go through them one-by-one. Business Insider USA

The museum even keeps some valuable specimens under lock and key. This rare spider-tailed horned viper was used to describe a brand-new species. Business Insider USA

On the other hand, the specimens in this tank are ambassadors for the rest of the collection. Business Insider USA

These are shown to private tour groups as samples of the wild things at the museum. Like this bonnethead shark, the only known omnivorous shark species. Business Insider USA

The tank also contains electric eels, which aren't actually eels but are a type of knife fish. Don't worry, they can only shock you when alive. Business Insider USA

These huge catfish are part of the doradid family, also known as talking catfish or thorny catfish, thanks to the bony, sharp lumps on the fish's side. Business Insider USA

There are some downsides to the wet preservation method. In life, this lancet fish looks like it's covered in chrome. But alcohol stripped it of that vibrancy. Business Insider USA

I still love visiting the Field Museum to see old mainstays like Sue the T. rex, but going behind the scenes is something I'll never forget and hope to do again. Business Insider USA