|Jacks are extremely variable in body shapes, sizes and colorations. They are distinguished from other families by having a narrow caudal peduncle and 2 anal spines detached from the rest of the anal fin (may be imbedded in larger fishes). The caudal fins are forked, each lobe equal in length in most species. They are mostly found in the Gulf and most attain large sizes. Smaller species and juveniles can be found in the estuaries. These fishes are fast swimmers and tend to school. They are important in both the commercial and recreational fisheries.