Photo of the Day 144

Leopard Seal, Antarctic Peninsula, Antarctica, 2006

Photograph by Paul Nicklen

A mature female leopard seal makes a threatening gesture to protect her kill from another leopard seal that had appeared behind the photographer. "More frightening than the canines," wrote the photographer, "was the deep jackhammer sound she let loose that rattled through my chest." Her display worked; the rival seal moved on.

(Text adapted from and photo shot on assignment for, but not published in, "Deadly Beauty," November 2006, National Geographic magazine)