To protect themselves against predators, blue tangs like Dory rely on the sharp pair of spines on their tails.

Fans of Finding Nemo, the latest animated hit from Disney and Pixar, know the film's friendly but forgetful supporting actress as Dory, but scientists call this colorful fish a blue tang (Paracanthurus hepatus). Blue tangs belong to the surgeonfish family, which draws its name from the scalpel-like spines that its members bear on their tails. Normally, these spines lie flat against the tail in a groove, but if a surgeonfish is disturbed or alarmed, it can erect its spines, slicing through the threat at hand by lashing its tail back and forth. Luckily, blue tangs do not see clownfish as a threat, so Nemo and Marlin look-alikes are safe from this fate!

Like clownfish, blue tangs inhabit coral reefs in the Pacific Ocean, where they feed mostly on aquatic plants and algae. These traits, along with the tang's bright blue coloration, make Disney's Dory easy to distinguish from the John Dory (Zeus faber), a carnivorous brown fish with a hefty set of jaws that swims in Atlantic waters. But snorkelers beware, even though blue tangs look like the friendlier of the two types of Dories, their scalpel spines can present a significant danger to outstretched fingers.

Clownfish and anemone. Photo:
Blue tangs are often called the Palette Surgeonfish, since their black stripe resembles an artist's palette.
Photo: John Rice
In the wild, blue tangs usually congregate loose groups and roam the reef looking for algae to eat.