Week Three: We take a lunch break and discover dermestids’ favorite fish!

Hello!

From exploring parks, searching for art stores, hiding from the heat in our rooms, and the ever present collections work we all had a fantastic third week in New York.

This week Senior Scientific Assistant Radford Arrindell took us on a tour of the ichthyology collection. He started out by explaining to us what ichthyology is (a new concept for some of our group).

Ichthyology is the study of fish. The fish preserved in the ichthyology collection are both vertebrates and modern, putting two strikes against them for those of us whose hearts truly lie with the invertebrate fossils we are working with.

I, however, always enjoy learning about the preservation of modern material. Though working with fossils comes with its own set of difficulties, you are essentially working with a pre-preserved collection. Most fossils are organisms and traces of organisms that have been preserved in rock, or they are made of the hard parts of organisms that have already survived thousands or millions of years. If you keep the conditions the same, and take care of the specimens, they will continue to survive.

In the Mapes Collection we have worked with concretions, medium-sized sedimentary rocks with multiple fossils in them. We’ve seen some individual fossils, that may have eroded or been extracted from the rock they were preserved in. There are microfossils, mounted on slides, for viewing under a microscope. We have also started working with some modern nautiloid shells in the past weeks, which though they are not lithified, as shells, they preserve rather well.

Some modern nautilus shells.

It is a different matter with modern organisms. Modern organisms usually need to be fixed in a chemical such as formalin that will stop the cells from decaying. They are then preserved in a liquid such as ethyl or isopropyl alcohol, which prevents bacteria growth.

The ichthyology collection contains four types of specimens, or four different types of “preps.”

There are alcoholic preps, created through the method described above and preserved in ethyl alcohol.

These sea horses are an example of an alcoholic prep.

There are stained preps, where organisms are treated with dye and enzymes. The treatment turns the organism transparent while simultaneously dying the cartilage red and bones blue. This enables researchers to look at the bones and cartilage in situ, comparing ossification, the formation of bones, in organisms at different developmental stages.

Fish prepared by staining. The official term for this preparation method is diaphanization, a term which, the first page of google results contains a youtube video on its pronunciation. Try saying diaphanization three times fast.

The third preparation type is tissue and muscle samples, similar to the tissue samples we saw the first week in the cryo collection.

Finally, they have skeletal preps, usually prepared by dermestid beetles. These beetles eat dead flesh off of specimens leaving only the bones. However, if left to their own devices they will eventually eat all the way through the bones as well. Mr. Arrindell explained how they have to entice the beetles away from a specimen once it is sufficiently cleaned. Apparently dermestids have a preference for tarpon.

Mr. Arrindell with a dermestid-cleaned stingray.

  

We also were shown the collection’s most iconic specimen, a female coelacanth. Called living fossils, coelacanths were thought to be extinct, found only in the fossil record. Then a live coelacanth was caught, and we realized they might not be quite as extinct as we had thought they were. (For more information on coelacanths see: http://vertebrates.si.edu/fishes/coelacanth/coelacanth_wider.html)

Female coelacanth (right) with smaller male coelacanth stored in a tank of 70% ethyl alcohol.

For a long time, it was unknown whether coelacanths gave birth to live young or laid eggs. When extracting DNA from the AMNH’s specimen, they found that she was actually pregnant and would have given birth to five live pups. These pups have since traveled around the world, with one traded to a museum in France and one in London, The other three housed here at the AMNH, preserved as various types of preparation.

We are all glad that at most we have to deal with pyrite disease, some crumbling rock matrix, and rehousing our specimens in archival quality materials (though I personally like the more finicky modern specimens).

On a less collections-y note, here are the absolute highlights of everybody’s week:

Sarah and Minda explored the area around Penn station, searching for art stores, book stores, yarn stores, and thrift stores, getting delicious Korean food, and visiting the “Between the Lions” library.

Keara and Sarah visited a fancy gem and mineral store and were stunned by the prices.

Alex went to participate in an art installation on Governor’s Island, called Write on it All.

Ernesto and Ryan ate fried plantains.

Minda found fireflies in her local park.

Ryan and his roommates celebrated Paul Bunyan day, and Ryan would like me to repeat the fact that he had fried plantains (he literally cannot stop mentioning this fact).

And that is all for this week!

Thanks to everyone who reads this.