A slender, deep-water shark whose upper tail lobe is as long as the rest of the body, giving a total length around 3 m (10 ft) of which half is tail. Metallic blue-gray above, white below, with disproportionately large eyes and a small mouth. It is shy, keeps its distance, and is seen more often as a silhouette than a shark.
The tail is a weapon and the mechanics were only filmed recently. The shark accelerates into a school of small fish, brakes hard with its pectoral fins, and throws the tail forward over its own head like a whip crack. The tip moves fast enough to drop the pressure of the water behind it into vapor, and the collapsing bubbles add a shockwave to the impact. One strike can stun several fish at once, and the shark turns back to collect them at leisure. Almost no other fish hunts by striking rather than biting.
The eyes explain the rest of the day. They are enormous and angled upward, tuned to spot prey silhouetted against dim light from below, which is what an animal hunting at 200 to 300 m needs. It comes shallower at night and, in some places, at dawn to visit cleaning stations, which is when divers see it at all.
Large eyes, long tail and a litter of two pups make for an animal with no capacity to absorb fishing pressure. It is Endangered, taken in enormous numbers as longline bycatch, and encounters here are exceptional.
The genus. Alopias Rafinesque 1810 - alṓpēx (fox). ETYFish
The species. Alopias pelagicus Nakamura 1935 - from pelágios (πελάγιος). ETYFish
- upper tail lobe as long as the rest of the body
- disproportionately large eyes, small mouth
- metallic blue-gray above with a sharp line to the white belly
- keeps its distance, usually seen as a silhouette
Why it's threatened
Threat classification from the IUCN Red List.
