File:Anomalocaris canadensis - Smithsonian Museum of Natural History - 2012-05-17.jpg

English: A fossil Anomalocaris canadensis on display in the Sant Hall of Oceans in the Smithsonian Museum of Natural History.

Anomalocaris is the name for a wide range of early sealife very similar to shrimp, scorpions, lobsters, and crabs.

Joseph Frederick Whiteaves first discovered these in 1892 in the Ogygopsis Shale in British Columbia, Canada.

Anomalocaris canadensis looked very much like a big shrimp cross-bred with a ray. It looked like a shrimp, but it numerous overlapping armored appendages along both sides. Theses "waved" up and down through the water, propelling it forward. It was a predator, and hunted visually. Its eyes were on long stalks that extended from the body, and the eyes were likea fly's -- with more than 16,000 individual lenses. Its mouth was a series of disks, which sliced and ground its food. Its throat was lined with stubby teeth, so food could not climb back out! It had two barbed arms which extended outward and curved backward, to stab food and bring it to the mouth.

Anomalocaris canadensis was one of the biggest creatures in the ocean at the time -- almost six feet long! This predator fed mostly on trilobites, and lived from 542 to 449 million years ago.

The Sant Hall of Oceans is the largest exhibit space in the museum, with 674 specimens and models in a 23,000-square-foot (2,136 sq. m) exhibition space. The hall features a replica of a 45-foot (13.7 m) long North Atlantic right whale and two preserved giant squid (one an adult, one a juvenile).

The hall is named for Victoria and Roger Sant of Washington, D.C., who donated $15 million to create and endow the hall. It opened in 2008. The exhibits, displays, videos, and signage in the hall was created in partnership with the U.S. National Oceanic and Atmospheric Administration (NOAA) to show the ocean as a global system.