Thresher Shark

Thresher Shark

Alopias vulpinus

Size:
to 20 ft including tail

Habitat:
open ocean, both coastal and over very deep water, also in the Mud Hole

Notes:
not especially dangerous

This shark feeds mainly upon small fishes which it stuns with its long tail. It has relatively weak jaws and small teeth for its size and is generally not considered a threat to man unless provoked. Thresher Sharks are capable of great bursts of speed, and also commonly leap completely out of the water, for reasons unknown. The Thresher is a favorite of shark fishermen, and is very good eating if cleaned and prepared properly. It is also a common bycatch of long-line commercial fishing. The Bigeye Thresher shark is even more bizarre ( it's purple ! )

Thresher Shark
Thresher shark in the Philippines. Note the large eyes and small mouth.
Thresher Shark
The tail is unmistakable
Thresher Shark
Threshers are known to jump completely clear of the water, like this one in Maine.

From way back when in 1996 ...

NJ Scuba
Diving Myths
by Dr. Jolie Bookspan, author of Diving Physiology in Plain English

Myth 1 - The Dive Reflex Protects You

diving myths

In the dive reflex, heart rate and limb blood flow decrease. Careful science ( that means we didn't accidentally step on the thermisters ) shows time and again that the dive reflex does not reduce the need for oxygen underwater as it does in marine mammals. Field studies ( where you're allowed to step on the thermisters ) indicate that the dive reflex does not extend breath-holding time. Occasional cases of human survival after very cold water near-drowning are not due to the dive reflex. Cold is the likely mechanism behind the reduced metabolism that permits survival.