Greater Amberjack

Amberjack

Seriola dumerili

Size
to 60" and 175 lbs. in the tropics

Description
The coloration of the greater amberjack is characterized by a dark stripe on the head which extends from the origin of the first dorsal gin through the eye. The back is blue or olivaceous, and the sides and belly are silvery-white. Occasionally there is an amber or pinkish cast to the body. Juveniles have five or six dark vertical bars along the sides.

Greater amberjack are found in the Mediterranean Sea and the Atlantic, Pacific, and Indian Oceans. In the western Atlantic, they are distributed from Nova Scotia to Brazil, including the Gulf of Mexico and the Caribbean, where they concentrate around reefs, rock outcrops, and wrecks. Greater amberjack that are at least 5 years of age, or 33.5 inches long, spawn from March through July. They may reach a size of 6 feet and weigh nearly 200 pounds. Voracious predators, greater amberjacks eat mostly crab, squid, and other fishes found on reefs. They are often found in small groups and are friendly to divers.

Amberjack eat a diet that is very typical of a deepwater, structure-holding fish: crabs, crustaceans, squid, and small fish.

These are active and pretty fish, silvery with yellow stripes. They seem to travel in large schools of small ones led a few larger individuals. It is not difficult to get within spearing range of these fishes, but they have been known to cause ciguatera poisoning if eaten, a little-understood but potentially fatal condition. Lesser Amberjack is similar.


Human Vision Underwater

When light travels from a less-dense medium like air to a more-dense medium like water, the rays are refracted or bent towards the normal or perpendicular of the surface between the two mediums. In crude terms, light going from air to water will tend to be straightened, while light going from water to air will tend to be ... um ... crookeded. Confused yet? Take a look at the figure below.

refraction
( Tautogolabrus adspesus )

In this figure, you can see the light rays traveling from an object in the water to your eyes, neglecting the effect of the flat glass lens of your mask. The blue lines trace the actual path of the light rays through the water and into the air, or conversely, through the air into the water - the direction really doesn't matter. As you can see, the rays are bent toward the perpendicular of the surface on the water side, and away from it on the air side.