Galapagos bullhead shark  (Heterodontus quoyi)

Classified as Data Deficient (DD) on the IUCN Red List (1).

A poorly known but highly distinctive species, the Galapagos bullhead shark has an enlarged, blunt nosed-head, ending in a pig-like snout, and striking spotted patterning covering its upperparts (2) (3). The overall colouration of the species is light grey or brown above and marked with numerous large black spots, while the underside is pale (2). The pectoral fins are relatively large compared to the body, allowing the Galapagos bullhead shark to clamber along the sea-bed, while the two smaller dorsal fins each bear a sharp spine to deter predators (2) (4). The teeth of this species, like other bullhead sharks, are unusual, with pointed, biting teeth at the front of the jaws, and flattened crushing teeth at the rear (2) (5).

As its common name suggests, the Galapagos bullhead shark is found around the Galapagos Islands in the south-east Pacific. Within the Galapagos Archipelago, this species has a restricted distribution, occurring in the west, along the east and north side of Fernandina Island and the west side of Isabela Island, and in the south, at the west side of Floreana Island. This species also occurs around the coast and offshore islands of Peru, although it has been suggested that the population from this region may in fact be a separate species (1)

The Galapagos bullhead shark typically occupies inshore sandy and rocky boulder strewn areas as well as coral reefs (2) (6). It is often observed resting on ledges projecting from vertical rock surfaces at depths of between 16 and 20 metres (2).

Generally active at night, the Galapagos bullhead shark forages along the seabed for shellfish, such as crabs, along with other marine invertebrates (6). The powerful rear teeth allow this species to crush shells with ease, digesting the soft innards and regurgitating the hard parts (4). In contrast to the common perception of most shark species as formidable, dynamic predators, the Galapagos bullhead shark is relatively docile, and a poor swimmer (4) (6). Despite its protective dorsal fin spines, this species has been known to be consumed by the much larger, notoriously voracious tiger shark (2).

The Galapagos bullhead shark produces eggs rather than live young. The eggs are roughly cone shaped, with a spiral flange running around the outside (2) (4). Like other bullhead sharks, this probably enables the egg to be wedged into a rock, making it difficult for predators to remove (4). The newly hatched sharks measure around 17 centimetres in length, and do not reach sexual maturity until they measure between 48 and 61 centimetres long (2) (6).

Although not currently of interest to commercial fisheries, the Galapagos bullhead shark is caught as bycatch by inshore fisheries outside of the Galapagos (1) (2). Owing to its restricted range, the Galapagos subpopulation is likely to be relatively small and so could be vulnerable to relatively small-scale negative events. Although protected from commercial fishing, the Galapagos subpopulation would be likely to be adversely affected if it became targeted by local fishermen (1).

The Galapagos subpopulation of the Galapagos bullhead shark is currently protected by virtue of its presence within the Galapagos Marine Reserve. Nevertheless, further research into this species’ population status, ecology and potential threats is necessary to ensure that it receives adequate conservation management (1).

To learn more about the Galapagos Marine Reserve visit:

• Charles Darwin Foundation:
  www.darwinfoundation.org/en/library/pubs/journals/br15049802

To learn more about the conservation of sharks and rays visit:

• Save Our Seas Foundation:
  www.saveourseas.com
• IUCN Shark Specialist Group:
  www.iucnssg.org
• Shark Research Institute:
  www.sharks.org
• Shark Trust:
  www.sharktrust.org

• Bycatch: in the fishing industry, the part of the catch made up of non-target species.
• Dorsal fin: the fins found on the back of the body of fish, or the raised structure on the back of most cetaceans.
• Invertebrates: animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones), echinoderms, and others.
• Pectoral fins: in fish, the pair of fins that are found one on each side of the body just behind the gills. They are generally used for balancing and braking.

1. IUCN Red List (July, 2009)
   http://www.iucnredlist.org
2. Compagno, L.J.V. (2001) Sharks of the world: an annotated and illustrated catalogue of shark species known to date. Food and Agriculture Organization of the United Nations, Rome.
3. Allen, G.R. and Robertson, D.R. (1994) Fishes of the tropical eastern Pacific. University of Hawaii Press, Honolulu.
4. Biology of Sharks and Rays (July, 2009)
   http://www.elasmo-research.org/education/shark_profiles/heterodontiformes.htm
5. Bannister, K. (1993) The Book of the Shark. New Burlington Books, London.
6. FishBase (July, 2009)
   http://fishbase.sinica.edu.tw/Summary/SpeciesSummary.php?id=744