Caranx sexfasciatus

Habitat: Bigeye jacks typically are found in the open ocean over deep reefs.

Average adult size: Adults can grow to be 2 feet long.

Natural history: Jacks are well-adapted to their lives in the open ocean. They are strong swimmers with streamlined bodies. Built for speed, the base of their forked tail is slender. Little fins, called scutes, channel the water efficiently around the jack, reducing drag. Bigeye jacks usually are found in large, spectacular schools numbering in the thousands. As you watch, you usually see pairs split away from the school. The female will be silver, but the male has turned jet black. This is his mating color, telling her he is ready to spawn. Jacks are broadcast spawners, releasing eggs and sperm into the open ocean. Juvenile bigeye jacks are sometimes seen in brackish-water, estuaries. Schools of jacks will quickly move onto the reef to feed on small reef fishes. Bigeye jacks are a popular game fish, targeted by sport and commercial fishermen.

Range: In the tropical Indo-Pacific, north to Baja, California.

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