X-rays in Peabody exhibit illustrate evolution of fish

A new exhibition opening at the Yale Peabody Museum of Natural History blends science and art with something distinctly fishy

Titled “X-ray Vision: Fish Inside Out,” the exhibit features 40 images exposing the inner workings of several species of fish. The show was created by the Smithsonian’s National Museum of Natural History and the Smithsonian Institution Traveling Exhibition Service, and will make its premiere at the Peabody July 2-Jan. 8.

Fish are vertebrates — animals with backbones — and have bodies supported by a bony skeleton. Variations in the skeleton, such as the number of vertebrae or the position of fins, can be documented with x-rays. The Smithsonian’s National Collection of these fish x-rays represent more than 70% of the world’s fish specimens and is the largest and most diverse collection of its kind in the world.

Although the x-rays featured in the national collection were made for research purposes, the black-and-white digital images are art-like in nature.

Arranged in evolutionary sequence, these x-rays give a tour through the long stream of fish evolution. The x-rays have allowed Smithsonian and other scientists to study the skeleton of a fish without altering the sampling, making it easier for scientists to build a comprehensive picture of fish diversity.

Enhancing the exhibition are specimens from the Peabody’s own renowned ichthyology collections. Two sections prepared by Gregory Watkins-Colwell, collection manager in vertebrate zoology, illustrate the history of ichthyology at Yale - from the founding of the museum in 1866 to current research being carried out by Thomas J. Near, a Yale ichthyologist and assistant curator of vertebrate zoology at the museum. Two of the Peabody’s founding curators — Othniel C. Marsh, professor of paleontology, and Addison Emery Verrill, professor of zoology — established the ichthyology collection, and it was Verrill who created the “wet” collection of specimens preserved in fluid now in the museum’s division of vertebrate zoology.

The fish collection at the Yale Peabody Museum has grown by more than 50% over the last five years as a result of a growing number of research projects involving Yale faculty, undergraduates, graduate students, and postdoctoral researchers. Most of the collections are from the biodiversity-rich areas of the southeastern United States and the Southern Ocean.

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“The Peabody Museum and Yale University offer an ideal setting to study the evolutionary history of fishes,” says Near. “This new exhibition highlights the amazing diversity that fish exhibit in their body plans, which is often reflected in the habitats they occupy and the types of food they eat.”

Collected from around the world, some on historic expeditions, the Peabody specimens also illustrate the diversity of fish. One of the specimens on view is a pagetopsis macropterus, collected in 2006 by Near from waters off the Antarctic peninsula. This species lacks hemoglobin in its blood cells so its blood is white and not red. Near’s research shows that this trait evolved before the ancestors of this species colonized around Antarctica, as a result of a deletion in its genetic code.

The curators of the exhibition, Lynne Parenti and Sandra Raredon, have worked in the Division of Fishes at the National Museum of Natural History collecting thousands of x-rays of fish specimens to help ichthyologists understand and document the diversity of fishes. Rare or unique specimens make particularly interesting and informative images, note the curators. X-rays may also reveal other details of natural history: undigested food or prey in the gut might reveal to an ichthyologist what a fish had for its last meal, they note. To make comparisons easier, radiographers x-ray one fish per frame — with each one facing left — but they will prepare shots of several fish if a scientist wants to compare a group.

The Smithsonian Community Grant program, funded by MetLife Foundation, is a sponsor of the exhibition.

The Yale Peabody Museum of Natural History is located at 170 Whitney Ave. and is open Monday through Saturday 10 a.m. to 5 p.m., and Sundays noon to 5 p.m. Admission is $9 adults, $8 seniors, and $5 children ages 3-18. Museum members, Yale I.D. holders and children under age 3 are always admitted free, as are visitors on Thursdays from 2 to 5 p.m. from September through June. For additional information, visit www.peabody.yale.edu or call the Infotape at 203-432-5050.