For casual observers to hardcore image makers and everyone in between, encounters with blue sharks are highly treasured, eagerly shared and long remembered. During the 1980s a small industry focused their efforts on taking divers out into the open ocean to see and photograph blue sharks. At the time blue sharks were abundant in California waters, but sadly fishing pressures have greatly reduced their populations here and around the world and the once thriving cottage industry that centered around diving with blue and shortfin mako sharks has all but disappeared.
FAMILY: Blue sharks are described in the family Carcharhinidae, a grouping commonly referred to as requiem sharks. A requiem is a mass or hymn for a deceased human and is an obvious reference to the way humans have long thought of sharks. Worldwide, there are 59 species of requiem sharks described in 12 genera.
GENUS AND SPECIES: Prionace glauca
DESCRIPTION: Compared to many sharks, the blue shark has a relatively slender body, long conical snout, large dark eyes, and long narrow pectoral fins. While some sharks possess six or seven gill slits, blue sharks and other requiem sharks only have five. The eyes of a blue shark are equipped with a translucent eyelid called a nictitating membrane that can be raised to protect the eye from sharp objects such as the bones of its prey. The upper jaw is equipped with curved, triangular-shaped teeth with serrated edges that help blue sharks cut into and rip their prey.
Like many open water fishes, blue sharks are distinctly countershaded, being darkly hued on their back and lightly hued on their underbelly.