Oarfish, the inspiration for classic "sea serpents," are rarely seen, but a pair of the elusive animals were recently filmed in shallow water, swimming under a boat. 

These animals usually live in deep water in oceans worldwide, including off the coast of the Baja Peninsula in Mexico, where the video was recorded. Normal depth for the creatures is between 1,500-3,300 feet beneath the surface of the water.

Researchers from the Shedd Aquarium in Chicago recorded the video in early March. 

Tim Binder, vice president of collection and planning for the aquarium, was leading an ecotourism expedition for members off the coast of La Paz, near Isla San Francisco. The animals swam under the boat as they circled. They had silver patterns and blue spots, along with distinctive crowns.

The pair of fish circled around the boat for almost half an hour, before beaching themselves onshore. The fish quickly expired once they were on the sand. Researchers do not know why the pair of fish killed themselves. This behavior is most common among fish who are very sick, or in a great deal of pain.

This species was first noted in 1772, and may have been the inspiration for fantastic stories of sea serpents, told by sailors during the golden age of sailing. They are the largest bony fish in the world, and adult oarfish can grow to be up to 56 feet long, and weigh as much as 600 pounds.

"Oarfish have shiny, silvery bodies, bright red crests on their heads... In 2001, divers inspecting a navy buoy in the Bahamas were the first to videotape a five-foot oarfish in the water," the National Oceanic and Atmospheric Administration wrote on its Web site.  

Oarfish are rarely seen in the wild, since they live at depths far deeper than most humans travel, keeping them well out of sight. The animals are usually only seen by people when they are injured or sick. The first-ever video of oarfish at their natural depth was not recorded until 2008. That individual was estimated to be between 20 and 30 feet long.

This species also has several other names, including ribbonfish (for their slender bodies), roosterfish, or the King of Herrings. Hardly sea serpents at all, these gentle slender creatures feed on zooplankton, small shrimp and jellyfish.

Oarfish appearing in such shallow water has some people asking if the animals might be swimming away from an impending earthquake. In Japanese folklore, appearances by the fish are said to foretell coming seismic action.

The video was released by the aquarium, and is available on You Tube.