Only documented since the 1980’s
The Smalleye Hammerhead (Sphyrna tudes) is part of the family Sphyrnidae. This species is common in the shallow coastal waters of the western Atlantic Ocean, from Venezuela to Uruguay. It prefers muddy habitats with poor visibility.
The yellow-orange pigments of the Smalleye Hammerhead come from the penaeid shrimp Xiphopenaeus kroyeri. This is the primary food source of juvenile Smalleye Hammerhead sharks. The adults get their coloring from sea catfish and their eggs.
Common Name– Ground Sharks
Status: IUCN Red List VULNERABLE
Average Size and Length: Smalleye Hammerhead sharks typically reach 3.9–4.3 feet in length.
Average Weight: Unknown
Teeth and Jaw: The mouth of the Smalleye Hammerhead is strongly curved, containing on either side 15–16 upper tooth rows and 15–17 lower tooth rows. The teeth have single narrow cusps with smooth or weakly serrated edges, that are angled in the upper jaw and upright in the lower jaw.
Head: The cephalofoil of Smalleye Hammerhead sharks is wide and long with an arched front margin bearing central and lateral indentations.
The cephalofoils of newborns are longer, more arched, and less indented in front than those of adults. The eyes are proportionately smaller than in other hammerheads and are equipped with nictitating membranes. The nostrils are positioned just inside of the eyes, each with a well-developed groove running towards the center of the cephalofoil.
Demographic, Distribution, Habitat, Environment and Range: Smalleye Hammerhead sharks are 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.
Diet: The yellow-orange pigments of the Smalleye Hammerhead seem to have been 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.
Ram-Suction Index: combination
Aesthetic Identification: The Smalleye Hammerhead has a bright golden color on its head, sides, and fins, which was only scientifically documented more recently in the 1980s.
The first dorsal fin is tall and slightly falcate (sickle-shaped), originating behind the pectoral fin bases; its free rear tip lies over the origin of the pelvic fins. The second dorsal fin is smaller than the first with a concave, trailing margin. The pelvic fins have nearly straight trailing margins. The anal fin is taller and longer than the second dorsal fin. The caudal fin has a well-developed lower lobe and a notch near the tip of the upper lobe.
Biology and Reproduction: Smalleye Hammerhead sharks are viviparous. Females have litters of five to 19 pups every year following a gestation period of 10 months. Low reproduction rates in comparison.
Behavioral Traits, Sensing and Intelligence: Adult males and juveniles are schooling and generally found apart from the solitary adult females.
The golden color may serve to conceal it from predators such as larger sharks.
Smalleye Hammerhead Future and Conservation: The Smalleye Hammerhead shark is an economically important bycatch of artisanal gillnet fisheries throughout its range and is used as food. In recent years, overfishing has caused marked declines in its numbers off Trinidad, northern Brazil.
Smalleye Hammerhead Recorded Attacks on Humans: unknown