Monterey skate. This skate is found where its name sugggests, in Monterey in California, USA. They grow to about 45-60cm long and are distinguised by the rings of small dots at the base of their pectoral fins. (Raja montereyensis)

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution

    Pine-cone dory. Named for its body shape that resembles pine-cones, these fish are found at depths of about 500m, mostly in temperate waters off western and southern Australia. It can also be found in sub-tropical and tropical waters.  (Oreosoma atlanticum)

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution

    Tropical hatchetfish.  Marine hatchetfish live in the dark depths of the ocean; this specimen was collected at about 850m down in the Pacific. As with many other deep-sea fishes, their eyes are large and their bellies have numerous small cream-colored spots that are bioluminescent. Each species emits its own unique pattern of light. (Argyropelecus lychnus)

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution

    Torrent loach.  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 not yet officially named. 

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution

    Short dragonfish. The broad, expanded pectoral fins of this small marine species recall the wings of mythical dragons. These fish are able to change colour to match their background. Despite their fierce appearance, dragonfish are harmless to humans and eat only invertebrates. (Eurypegasus draconi)

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution

    Wedge-tail triggerfish.  Triggerfish discourage predators by erecting two sharp dorsal spines: a large, thick one and a shorter spine behind it. The second spine is the ‘trigger’, it locks the first one in place. (Rhinecanthus rectangulus)

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution

    Crisscross prickleback.  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 this specimen from California was preserved a century ago, in 1910. (Plagiogrammus hopkinsii)

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution

    Prillo.  Large, ornate pectoral spines extend from the sides of these small South American catfish. When locked in an open position, the spines prevent predators from swallowing the catfish. (Physopyxis lyra)

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution

    Lookdown fish. Because of its sloped head and the enlarged crest on its skull, the lookdown fiish appears to look down as it swims. These fish are often found in small schools. (Selene vome)

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution

    Winghead shark.  This shark has its eyes set at the tips of its wide, T-shaped head. Scientists think that this positioning gives it a broader and more precise field of view. The winghead is one of about ten species of hammerhead sharks. (Eusphyra blochii)

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution

    Viper moray eel.  Moray eels are legendary predators on coral reefs. Note the second set of ‘jaws’ in the throat: these are the gill arches, present in all fish – they support the gills, which they use to respire. (Enchelynassa formosa)

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution

    Long-spine porcupine fish.  To ward off predators, a porcupine fish inflates its body by pumping water into its stomach. The body becomes a round, rigid ball bristling with spines – but when the fish is relaxed, the spines lie flat against the body. (Diodon holocanthus)

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution

    Longnose batfish.  Flat and wide, batfish look like they’ve been stepped on. They feed by skimming for prey along sandy bottoms. As you can see, this longnose batfish has a taste for molluscs. (Ogcocephalus corniger)

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution

    Grooved razorfish.  Razorfish, or shrimpfish, have a unique swimming style: they keep their bodies vertical (heads down, tails up) while propelling themselves forward in schools. Note that the back of the fish is bony and nearly straight – all of its fins are on its belly. (Centriscus scutatus)

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution

    Orange bellowfish.  Between the bellowsfish’s skull and dorsal (back) fin is a fleshy tuft that is supported by many thin rods of bone. This species lives on continental shelves at depths of 580m. (Notopogon fernandezianus)

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution.

    Dhiho’s seahorse.  Just a few centimetres long, this elegant species 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. (Hippocampus sindonis)

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution

    Smalltooth sawfish.  The long toothy rostrum or saw gives these fish their common name. They use the saw to dig in the sand for crustaceans or to attack prey by vigorously slashing from side to side. Note that the radiograph is a composite: where the two images were spliced, the vertebral column appears to be broken behind the head. (Pristis pectinata)

    Photo Credit: Radiograph and fish photograph by Sandra J. Raredon, Division of Fishes, National Museum of Natural History, Smithsonian Institution

X-ray Vision: fish inside out

By AG STAFF | March 5, 2015

An exhibition at the Australian National Maritime Museum in Sydney features unusual images captured with a digital radiographic machine and arranged in an evolutionary sequence. Smithsonian National Museum of Natural History fish curator Sandra Raredon captured the images of thousands of fish specimens. All up, the institution, in Washington DC, has four million individual specimens representing 70 per cent of total fish diversity. The X-rays allow scientists to document internal features without ruining specimens, but they also make for unusual abstract artworks. The exhibition will be open until February 2016.