Jack Crevalle (Caranx hippos) is a powerful, large marine fish found throughout the tropical and subtropical waters of the Atlantic Ocean, ranging from Nova Scotia to Uruguay and the Gulf of Mexico. This deep-bodied species is a voracious, opportunistic predator known for aggressive feeding behaviors that often create spectacular surface disturbances. Its diet and hunting methods are finely tuned to exploit the abundance and movement of prey in its varied habitats.
The Primary Menu: Key Prey Items
The adult Jack Crevalle is overwhelmingly piscivorous; studies indicate that fish make up between 74% and 94% of its total food intake. The preferred targets are small, schooling baitfish, which are easier to capture in large quantities than solitary prey. This preference often places members of the Clupeidae family, such as menhaden, herring, and sardines, at the top of the menu.
The Jack Crevalle also consumes other fish species opportunistically, including pinfish, sparids, and smaller members of its own family, Carangidae. The specific composition of the fish diet shifts depending on the local ecosystem and season. While fish form the bulk of the calories, various invertebrates play a secondary role.
Crustaceans like shrimps and crabs are commonly found in the stomachs of adults, particularly when schooling fish are less available. Mollusks and cephalopods, such as squid, are also consumed, adding diversity to the predator’s intake. These invertebrate items become more important depending on the fish’s location, with some populations showing a higher reliance on them than others.
Feeding Strategy and Hunting Behavior
Jack Crevalle are diurnal predators, conducting the majority of their hunting during daylight hours. A defining characteristic of their feeding is the tendency to hunt in large, fast-moving schools. This coordinated group behavior is highly effective for overwhelming schools of baitfish.
The school works together to corner and compact their prey, often creating what anglers refer to as a “bait ball.” This activity results in a visible disturbance on the water’s surface that looks like the water is churning. Their speed and stamina are used to maintain the tight formation, disorienting the smaller fish and making them easier targets.
The fish exploit various coastal structures to maximize hunting success. They utilize jetties, bridges, seawalls, and mangrove edges as natural barriers to trap or ambush prey. Their hunting technique involves quick, aggressive strikes, as they are drawn to fast-moving targets. They move between open ocean, offshore wrecks, and brackish estuarine waters, always seeking areas with strong current and high concentrations of bait.
Dietary Changes Based on Size and Age
The diet of the Jack Crevalle undergoes a significant transformation as the fish grows from a small juvenile to a large adult. Newly hatched juveniles begin by consuming zooplankton, such as small copepods. As they develop, their diet quickly shifts to include slightly larger, more accessible invertebrates.
Young Jack Crevalle in inshore and estuarine habitats primarily feed on small crustaceans like shrimps and crabs, along with larval fish. This crustacean-heavy diet provides the energy necessary for rapid growth. Once the fish reach a larger size, they begin the transition to a diet dominated by bigger fish species.
The shift to an adult diet occurs as their body size and swimming capability allow them to hunt larger, faster prey in open water. This results in the highly piscivorous feeding habit of the adult, which sustains itself on schooling baitfish.