Scalloped Hammerhead Shark

§ Quick facts

§ Encyclopedia

The scalloped hammerhead is a species of hammerhead shark in the family Sphyrnidae. It was originally known as Zygaena lewini. The Greek word sphyrna translates into "hammer" in English, referring to the shape of this shark's head, which is its most distinguishing characteristic. The shark's eyes and nostrils are at the tips of the extensions. It is a fairly large hammerhead, but is still smaller than both the great and smooth hammerheads.

Source: Wikipedia — Scalloped hammerhead · Licensed under CC BY-SA 4.0

§ Identification

Field marks. Distinctive scalloped "hammer" head with grooves along the leading edge. Bronze-gray above, white below.

Similar species. Great Hammerhead (much larger, straighter hammer). Smooth Hammerhead (no scalloping).

Voice. Silent.

§ Diet & behavior

Diet. Sardines, herring, mackerel, squid, octopus, stingrays, smaller sharks. Use the hammer-shaped head to pin stingrays.

Behavior. Forms large schools of 100+ around seamounts during the day — among the most spectacular sights in the open ocean.

§ Range

Tropical and warm temperate seas worldwide; off both US coasts

§ Habitat

Coastal and pelagic waters; juveniles use estuaries as nurseries

§ Threats

Targeted shark-fin fishing, accidental bycatch, habitat degradation in nursery areas.

§ Conservation status

According to the IUCN Red List, the scalloped hammerhead shark is currently classified as Critically Endangered.

§ What helps

Avoid shark-fin products. Support international fishing regulations. Choose certified sustainable seafood.

§ Further reading

• Wikipedia — Scalloped hammerhead
• www.fisheries.noaa.gov — authoritative profile of Sphyrna lewini
• IUCN Red List · taxon 39385
• iNaturalist · taxon 49810
• GBIF occurrence records
• Encyclopedia of Life — Sphyrna lewini

§ Sources cited

• NOAA Fisheries
• The Shark Trust
• MarineBio Conservation
• IUCN Red List 2018