Bar Jack

Photo: Ryan Mannette · CC BY-NC-SA

Bar jacks form large polarized schools over the reef edge at Los Testigos, hunting cooperatively to herd baitfish against the reef structure. Their metallic blue-silver flanks with the characteristic black and electric-blue lateral stripe flash as schools wheel in unison — a sight amplified by the exceptional visibility. These schools reach several hundred individuals at Los Testigos, a population size that indicates an unfished, fully functioning reef ecosystem.