Black jacks – Caranx Lugubris, as researchers normally refer to them, are a large species of fish from the family Carangidae, and are found in a wide range of tropical areas around the world. These fish are unique, powerful predators that have the ability to take on a variety of crustaceans and mollusks as prey. They dwell in the lower regions of the deep reef, and seldom venture in shallower waters. Jacks are known to live both in schools and as individual members of the species that may even school with other species on occasion, mainly in order to hunt together.
Caranx Lugubris is a uniquely large species of carangid. In fact, aside from the yellowtail amberjack, which can reach lengths of over 2.5 meters, the black jack can be considered the second largest carangid in the world, growing to sizes of more than 1 meter while weighing just over 17 kg. The fish have a similar body shape to many other members of the Caranx species, with a compressed shape and a slightly more convex dorsal form. The fish’s strong outer canines stand out as both sharp and powerful, mainly used to shatter the shells of crustaceans as the carangid hunts and feeds on them.
Upon the maturity of black jacks, Caranx Lugubris species develop 9 dorsal spines and a total of 20-22 soft dorsal rays. They also have a smaller number of only 3 anal spines and 16 anal soft rays. They mainly develop as an insular species that is mainly restricted to ocean waters and can seldom be found in shallow banks, even though they may be spotted on the outer edge of reef drop-offs on occasion. They are predominantly found in the Western Indian Ocean, off the shores of South Africa and the Western Atlantic Ocean. Specific locations include Bermuda, Seychelles, the Gulf of Guinea, and Cape Verde.
Black jacks are hunters that can easily spot and hunt down other fish and sea creatures. Due to their silver color, they can camouflage with ease and their remarkably resilient bodies allow them to be just as fast, strong, and efficient both near the reef and at more than 1,200 feet below the surface. When it comes to humans interacting with black jacks, Caranx Lugubris are known to be quite benign, and despite their predatory status, they don’t openly attack divers without being provoked.