Fish bones tell stories in Fernbank exhibit

“Fish live in nearly every watery habitat on Earth, from sunlit freshwater streams to brackish bays, and the deepest seas,” notes an exhibit now on display at Fernbank Museum of Natural History. “This extreme habitat variation has resulted in an array of complex body shapes, sizes, and adaptations—many of which can be seen in the skeleton.” 

The exhibit, X-Ray Vision: Fish Inside Out, invites visitors to “peek beneath the scales and explore the intricate boney skeletons of fish, stingrays, eels, and seahorses through dramatic black and white x-rays,” states the museum’s introduction to the exhibit.  

Unlike most of the museum’s exhibits, X-Ray Vision is made up entirely of panels along a wall, like artwork in a gallery. The 40 radiograph images are accompanied by “detailed notations regarding the scientific importance of and differences between species’ evolutionary development,” theintroduction states. 

The x-rays of sea life are like pieces of art, but, according to Fernbank, they provide insight into fish evolution, anatomy, and the impact of environmental changes on aquatic species “in a level of detail reminiscent of a fine engraving.” 

Explaining the significance of x-ray images for scientific study, one panel states, “The bony skeleton is a key source of information about fish evolution because bones and teeth are the most durable part of any vertebrate body. The Smithsonian has x-rayed thousands of fish specimens to help ichthyologists [scientists who study fish] understand and document the diversity of fishes, to estimate the number of species, and to compare their structures.” 

The National Collection of Fishes at the Smithsonian features “nearly five million specimens from habitats worldwide, preserved in alcohol in more than a half million containers.” The National Collection of Fishes is the largest, most diverse, and most important collection of its kind, according to the exhibit. 

“The collection is a ‘fish library.’ Specimens are catalogued, organized, and set on shelves in order of evolutionary sequence, and they are regularly taken down or sent out on loan to be studied by researchers, students, or Smithsonian scientists,” a panel in the exhibit notes. 

The collection includes 24,800 of the world’s 32,000 fish species, the panel states. “Some species are represented by just one specimen. Many others have numerous representatives—males, females, juveniles, larvae, even eggs—from a variety of habitats, allowing scientists to describe a species accurately and completely. The oldest specimens in this collection date from the mid-1800s, and thousands of new ones are added each year. Fieldwork and exchanges or donations from other museums constantly expand this priceless archive of the natural history of fishes.” 

Fish skeletons record patterns of evolution, the exhibit states. “The rainbow trout has one soft dorsal fin. The striped bass has two dorsal fins, one spiny and one composed of hard spines and soft rays. According to our current understanding of fish evolution, these differences indicate that the striped bass is more highly evolved in some of its features than the relatively primitive rainbow trout. X-rays allow ichthyologists to easily examine and compare such details.” 

To make comparison 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 exhibits explains.  

Rare or unique specimens make particularly interesting (and informative) images, explains the panel next to the x-ray image of a two-headed shark with two backbones. “But x-rays may also reveal other details of natural history, undigested food or prey in the gut, for example, tells us what the fish had for its last meal,” the panel continues. 

X-Ray Vision: Fish Inside Out will be at Fernbank Museum of Natural History through Nov. 8. The museum is located at 767 Clifton Road, Atlanta NE. For more information, visit www.fernbankmuseum.org.