Scalloped Hammerhead in Galápagos: Facts and Where to See It

The flattened, hammer-shaped head is called a cephalofoil. It improves the shark's vision and gives room for more electroreceptors, the sensors hammerheads use to find prey on or under the seabed. The scalloped edge at the front tells this species apart from its relatives.

• Body. Slender, bronze-brown above and white below, with narrow, backward-pointing teeth for prey it swallows whole.
• Schools. In Galápagos they gather in schools of up to several hundred. Why they do so is still unknown.
• Live young. Pups are nourished through a placenta-like link for 9 to 12 months and born in shallow coastal water. In 2017, nursery sites were found inside the Galápagos Marine Reserve.

Scalloped hammerheads migrate through warm temperate and tropical waters of the Atlantic, Indian and Pacific Oceans. They eat schooling fish such as sardines, herring and mackerel, as well as stingrays, squid and crustaceans. In Galápagos they gather along the current edges of the remote northern islands, Wolf and Darwin, and turn up occasionally at Kicker Rock off San Cristóbal.

Guide sighting records list hammerheads at 5 sites. 2 are rated Likely, both dive sites in the far north: Wolf and Darwin Arch, where they school along the current edge. Gordon Rocks off Santa Cruz and the channel at Kicker Rock off San Cristóbal are rated Possible, and Kicker Rock is the one site where snorkellers have a chance too. Devil's Crown off Floreana is rated Rare.

Hammerheads are in the marine reserve all year. The Galapagos Conservation Trust gives the highest numbers in January and the lowest in May, while the guide sighting records note the largest schools of the year at Darwin Arch from June to November. In the next twelve months, 154 departures stop at a site where they are seen.

Yes, they are listed as Critically Endangered. Commercial and illegal fisheries increasingly target them for their fins, which are valued for shark fin soup, and they die as bycatch in trawls, purse-seine nets, gillnets and longlines. Many pups are caught by small-scale coastal fishing.

Protection. Inside the Galápagos Marine Reserve they are protected by law, and Ecuador tightened controls with two decrees in 2007. Internationally, the species is on CITES Appendix II, so all trade must be registered.

1. Booking a route without Wolf and Darwin. Both Likely sites are there, and they are reached only on dive itineraries.
2. Expecting schools on a snorkel. Kicker Rock offers a chance; the big schools are at depth on dives in the north.
3. Ignoring the season. Numbers are highest in January and lowest in May.