More Anatomy

In the X-ray image of this Viper Moray Eel ( Enchelynassa canina ), note the second set of jaws in the “throat”; these are the gill arches, which are present in all fish. Gill arches support the...
The clearly pictured spines, rays and snout make identifying this longnose butterflyfish ( Forcipiger longirostris ), which was collected in French Polynesia in 2004, straightforward in this X-ray...
This common octopus ( Octopus vulgaris ) doesn't have a jetpack to help him zoom through the water, but he's got something pretty close: a siphon that shoots water. (It's the little orange/yellow cup...
The distinctive form of a winghead shark ( Eusphyra blochii ) is revealed by an X-ray image. The Winghead Shark, one of about ten species of hammerhead sharks, has its eyes set at the tips of its...
This close-up photo shows the tough, serrated ring around the opening of a giant squid sucker. The ring is made of chitin—the same material that’s in your fingernails. Using suction, the sucker...
Sperm whales have conical teeth on their long, narrow, lower jaw. The teeth fit neatly into sockets in the upper jaw, which has no teeth. This arrangement is a perfect adaptation for slurping up soft...
Inside the giant squid's sharp beak is a tongue-like organ called the radula (shown in yellow). Covered with rows of tiny teeth, it rams bite size pieces of food down the squid's throat. The pieces...
The Palauan primitive cave eel ( Protanguilla palau ) has an evolutionary history that dates back some 200 million years . Because of this and the fact that it has retained some primitive features,...
The elongated body, characteristic long and narrow snout, and small teeth make the slender snipe eel ( Nemichthys scolopaceus ) easily identifiable in this X-ray image. Snipe eels live at great...
A mass of white muscle the size of a softball surrounds the dark brown beak of a giant squid. Learn more about this animal's oversized anatomy in our Giant Squid section .
Giant squid have the largest eye in the animal kingdom. At up to 10 inches in diameter, people often describe it as the size of a dinner plate -- or, in other words, as big as a human head. Here,...
A right whale opens its mouth wide, revealing huge plates of baleen hanging from its upper jaw. There are between 200 and 270 baleen plates on each side of a right whale's upper jaw. They work like a...
An X-ray image of a Monterey skate ( Raja montereyensis ) reveals a spine that extends like a tail out from the pelvic fin. The skeletons of skates, rays, chimaeras, and sharks are made of cartilage...
Scientists in the Division of Fishes at the Smithsonian's National Museum of Natural History use X-ray imaging to study the complex bone structure and diversity of fish. This image gallery showcases...
An X-ray image of grooved razorfish ( Centriscus scutatus ). Razorfish are encased in thin, transparent bony plates attached to their spines, which you can see in the X-ray. Also known as shrimpfish...
Tropical hatchetfish ( Argyropelecus lychnus ), like the one shown in this X-ray photograph, live in the dark depths of the ocean ; this specimen was collected at about 2,789 feet (850 meters) in the...
Comb jellies (such as this Bolinopsis species) are named for their combs: the rows of cilia lining their bodies that propel them through the ocean. Read more about jellyfish and comb jellies .
Hundreds of powerful suckers stud the flattened club at the end of the giant squid’s long feeding tentacle. They help the squid capture and hang on tightly to its prey. They also leave deep scars in...
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