fins, pelvic fins, and anal fin are bright yellow to orange with a metallic or iridescent sheen. Newborn sharks are gray above, darkening on the first dorsal fin and upper caudal fin lobe, and whitish below. They gain a bright yellow cast on their undersides by a length of , which turns to orange by a length of . The golden color is brightest in sharks long, and tends to fade with the onset of sexual maturity. Distribution and habitat The smalleye hammerhead is found along the eastern coast of South America from Uruguay to Venezuela, though it seldom occurs further west than the Orinoco Delta southeast of Trinidad. Reports of this species from off Panama, Mexico, and western Florida are unconfirmed; records from other parts of the world are most likely erroneous, resulting from its tangled taxonomic history. It is among the most abundant sharks within its range. This species inhabits inshore murky waters deep, over muddy bottoms. Segregation occurs by sex and age; newborns and juveniles under long are found in the shallowest waters, moving deeper after a few months of life. Adult females are mostly found at depths of , while larger juveniles and adult males are mostly found at depths of . This species is tolerant of brackish water, and can be found over a salinity range of 20–34 ppt. Biology and ecology Four other species of hammerhead sharks overlap in range with the smalleye hammerhead - the small-sized scoophead and bonnethead, and the large-sized scalloped hammerhead and great hammerhead. Little competition occurs between these species because of their differing habitats and dietary preferences. The smalleye hammerhead is the dominant hammerhead in shallow, muddy areas, where high turbidity limits the utility of vision (hence its smaller eyes). Adult males and juveniles of both sexes form schools of uniform body size; these schools do not appear to relate to reproduction or migration. Adult females are apparently solitary. Young smalleye hammerheads under long feed predominantly on penaeid shrimp, mostly Xiphopenaeus kroyeri. Larger sharks feed mainly on bony fishes, especially ariid sea catfish and their eggs. The shrimp and the surface mucus layer and eggs of the catfish contain carotenoid pigments that appear to be the source of the sharks' golden color; whether the pigments in the catfish also ultimately come from the shrimp is uncertain. Another shark species in the region, the yellow smooth-hound (Mustelus higmani), also feeds