Smalleye Hammerhead

The smalleye hammerhead or golden hammerhead (Sphyrna tudes) is a small species of hammerhead shark, family Sphyrnidae, common in the shallow coastal waters of the western Atlantic Ocean from Venezuela to Uruguay. It favors muddy habitats with poor visibility, reflected by its relatively small eyes. Adult males and juveniles are schooling and generally found apart from the solitary adult females. Typically reaching 1.2–1.3 m (3.9–4.3 ft) in length, this shark has a unique, bright golden color on its head, sides, and fins, which was only scientifically documented in the 1980s. As in all hammerheads, its head is flattened and laterally expanded into a hammer-shaped structure called the "cephalofoil", which in this species is wide and long with an arched front margin bearing central and lateral indentations.

The yellow-orange pigments of the smalleye hammerhead seem to be acquired from the penaeid shrimp Xiphopenaeus kroyeri, the main food of juvenile sharks, and from sea catfish and their eggs, the main food of adults. The golden color may serve to conceal it from predators such as larger sharks. This species is viviparous, with the developing embryos sustained by a placental connection formed from the depleted yolk sac. Females bear litters of 5–19 pups every year following a gestation period of 10 months. Reproductive seasonality, litter size, and size at maturity vary between geographical regions. Because of its abundance, the smalleye hammerhead is an economically important bycatch of artisanal gillnet fisheries throughout its range and is utilized as food. In recent years, overfishing has caused marked declines in its numbers off Trinidad, northern Brazil, and probably elsewhere. Coupled with its low reproductive rate, this has led the International Union for Conservation of Nature (IUCN) to list it under Vulnerable.