These fish are aptly named; their rounded, compressed bodies are completely covered (with the exception of the caudal peduncle) with very large, strong, platelike scales called scutes, which are fortified with prominent ridges. The first dorsal fin is composed of four to seven strong, disunited spines which vary in length; the second dorsal fin and anal fin are small, spineless and rounded, situated far back of the convex head. The pectoral fins are somewhat elongate and the caudal fin is truncate.