Galapagos shark
A large, abundant reef shark of tropical oceanic islands.
The Galapagos shark (Carcharhinus galapagensis) belongs to the requiem shark family, Carcharhinidae, and lives in tropical waters around the globe. It prefers clear, reef-filled areas near oceanic islands, where it is frequently the most numerous shark species. This large predator typically grows to 3.0 meters (9.8 feet) and has the streamlined, fusiform body common to reef sharks. Telling it apart from the dusky shark (C. obscurus) and the grey reef shark (C. amblyrhynchos) is notoriously tricky. One key clue is its tall first dorsal fin, which has a slightly rounded tip and starts above the rear edges of the pectoral fins.
An active hunter, the Galapagos shark often appears in big groups. Its diet mainly consists of bottom-dwelling bony fish and cephalopods, but larger individuals eat a wider range of prey, including other sharks, marine iguanas, sea lions, and even trash. Like other requiem sharks, it reproduces via viviparity. Females give birth to litters of 4 to 16 pups every two to three years. Young sharks stay in shallow water to avoid being eaten by adults. The International Union for Conservation of Nature (IUCN) lists this species as least concern, but it has a slow reproductive rate and faces heavy fishing pressure throughout its range.
Robert Evans Snodgrass and Edmund Heller first described the Galapagos shark in 1905, naming it *Carcharias galapagensis*. Later scientists moved it to the genus *Carcharhinus*. The holotype was a 65-centimeter (2.13-foot) fetus from the Galapagos Islands, which explains the species name *galapagensis*. In 1982, Garrick placed the Galapagos shark and the dusky shark at the center of the "obscurus group," one of two main groups within *Carcharhinus*. This group includes the bignose shark (C. altimus), Caribbean reef shark (C. perezi), sandbar shark (C. plumbeus), dusky shark, and oceanic whitetip shark (C. longimanus)—all large, triangular-toothed sharks defined by a ridge between their two dorsal fins. Using allozyme data in 1992, Naylor confirmed this group and added the silky shark (C. falciformis) and the blue shark (Prionace glauca). The closest relatives of the Galapagos shark turned out to be the dusky, oceanic whitetip, and blue sharks.
This species mainly lives near tropical oceanic islands.
Quick Facts
- Genus
- Carcharhinus
- Species
- galapagensis
Facts from the source article.
Lore & Background
The Galapagos shark was originally described as Carcharias galapagensis by Robert Evans Snodgrass and Edmund Heller in 1905; the holotype was a 65 cm long fetus from the Galapagos Islands. Garrick (1982) placed it in the 'obscurus group' within Carcharhinus, and its closest relatives were found to be the dusky, oceanic whitetip, and blue sharks. An identifying character of this species is its tall first dorsal fin, which has a slightly rounded tip and originates over the rear tips of the pectoral fins. The Galapagos shark can be distinguished from the dusky shark in having taller first and second dorsal fins and larger teeth, and from the grey reef shark in having a less robust body and less pointed first dorsal fin tip, though these characters can be difficult to discern in the field. The species has 58 precaudal vertebrae, compared to 86–97 in the dusky shark and 110–119 in the grey reef shark.
Reader's Guide
The Galapagos shark is an active predator often encountered in large groups. It feeds mainly on bottom-dwelling bony fishes and cephalopods; larger individuals have a much more varied diet, consuming other sharks, marine iguanas, sea lions, and even garbage. As in other requiem sharks, reproduction is viviparous, with females bearing litters of 4–16 pups every 2 to 3 years. The juveniles tend to remain in shallow water to avoid predation by the adults. The International Union for Conservation of Nature (IUCN) has assessed this species as least concern, but it has a slow reproductive rate and there is heavy fishing pressure across its range. At some locations they form large aggregations, though these are not true schools. During group interactions, Galapagos sharks are dominant to blacktip sharks but deferent to silvertip sharks of equal size. When confronted or cornered, the Galapagos shark may perform a threat display similar to that of the grey reef shark, involving an exaggerated, rolling swimming motion while arching its back, lowering its pectoral fins, puffing out its gills, and gaping its jaw.
Did You Know?
- The Galapagos shark was originally described from a 65 cm fetus collected in the Galapagos Islands.
- Females give birth to 4–16 pups every 2 to 3 years after a gestation period of around one year.
- The species has been observed attacking Galapagos fur seals, sea lions, and marine iguanas.
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