NEW HAVEN —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, are documented with X-rays. The Smithsonian's National Collection of these Fish X-rays represent more than 70 percent 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 strikingly elegant images demonstrate the natural union of science and art and are a visual retelling of the evolution of fish.
X-ray Vision: Fish Inside Out, premiering a the Yale Peabody Museum of Natural History in New Haven on Saturday, July 2, is an exhibition that showcases these dramatic prints exposing the inner workings of the fish. Created by the Smithsonian's National Museum of Natural History and the Smithsonian Institution Traveling Exhibition Service (SITES), it will remain on view through January 8, 2012.
The exhibition features 40 black-and-white digital prints of several different specimens of fish. 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. In sections on the History of Ichthyology and Modern Ichthyology at Yale Peabody Museum, prepared by Gregory Watkins-Colwell, collection manager in vertebrate zoology, these specimens illustrate the distinguished history of ichthyology at Yale, dating from the founding of the Museum in 1866 through to current research being carried out by Dr. Thomas J. Near, ichthyologist and assistant curator of vertebrate zoology. Two of the Peabody's founding curators—Professor of Paleontology Othniel C. Marsh and Professor of Zoology Addison Emery Verrill—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 timing of this exhibition is appropriate, as the fish collection at the Yale Peabody Museum has grown by more than 50% over the last five years. This activity in the collection is a result of a growing number of research projects involving Yale faculty, undergraduates, graduate students, and post-doctoral researchers. Most of the collections are from the biodiversity rich areas of the southeastern United States and the Southern Ocean. "The Peabody Museum and Yale University offer an ideal setting to study the evolutionary history of fishes" said Dr. Near. Adding, "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 wonderful diversity of fish. One of the specimens on view is a Pagetopsis macropterus, collected in 2006 by Dr. Near from waters off the Antarctic Peninsula. This species lacks hemoglobin in its blood cells so its blood is white and not red. Dr. Near's research shows that this trait evolved before the ancestors of this species colonized waters around Antarctica, as a result of a deletion in its genetic code.
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. 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. 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.
Photo credits and captions
Viper Moray, radiograph and fish photograph by Sandra J. Raredon,
Division of Fishes, National Museum of Natural History, Smithsonian Institution.
Moray eels are legendary predators on coral reefs. Note the second set of jaws in the "throat"; these are the gill arches, which are present in all fish. Gill arches support the gills, the major respiratory organ of fish.
Dhiho's Seahorse, radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution.
Just over one inch long, this elegant fish is readily identified as a seahorse by its characteristic head. The body ends in a tail that can curl around and hold on to algae or coral. This species is found only in the waters around Japan.
Torrent Loach, radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution.
The crescent-shaped paired fins on the underside of torrent loaches work like suction cups to help them hold their position on a rock or streambed in fast-flowing waters. These specimens belong to a newly discovered species that has not yet received a scientific name.
Lookdown, radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution.
Because of its sloped head and the enlarged crest on its skull, the lookdown appears to "look down" as it swims. These fish often swim in small schools.
Crisscross Prickleback, radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution.
The radiograph reveals the fine details of this skeleton—especially the long, spiny dorsal fin that forms the prickles on the fish's back. The quality of detail is remarkable, considering that this specimen from California was preserved a century ago, in 1910.
Editor's note: All information in this post was contributed. It is unedited here.