Scalloped bonnethead

The scalloped bonnethead (Sphyrna corona) is a rare, little-known species of hammerhead shark, and part of the family Sphyrnidae. Its other common names include the mallethead shark and the crown shark.[1] It is found in tropical and subtropical waters in the eastern Pacific Ocean, from Mexico to Peru, and possibly as far north as the Gulf of California.[2] It frequents inshore habitats over soft bottoms (mud, sand, and gravel) to a depth of 100 m, and also enters mangroves and estuaries.[3]

Scalloped bonnethead

Near Threatened  (IUCN 3.1)[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Carcharhiniformes
Family: Sphyrnidae
Genus: Sphyrna
Species:
S. corona
Binomial name
Sphyrna corona
Range of the scalloped bonnethead

Probably the smallest species of hammerhead shark, the scalloped bonnethead measures up to 92 cm long.[4] Its mallet-shaped head, called a cephalofoil, is moderately wide (24-29% of total length) and elongated lengthwise. The front margin is broadly arched, with shallow lateral and medial indentations, and no prenarial grooves. The mouth is small and strongly arched. The anal fin is long and has a nearly straight rear margin. Its coloration is gray above and white below, with no prominent fin markings. The similar scoophead (Sphyrna media) can be distinguished by a shorter snout, a broader mouth, and a deeply concave anal fin margin.[2]

Like other hammerheads, the scalloped bonnethead is viviparous, with presumably two pups per litter. The young are born at 23 cm or above; an adolescent male has been recorded at 51 cm long, and an adult at 67 cm. It may be taken by local inshore fisheries, but data are lacking.[2] It feeds on or near the bottom, on crustaceans, molluscs, cephalopods, echinoderms, and bony fishes.[3]

  • Head, underside
  • Head, top side
  • Jaws

References
  1. Mycock, S.G. (2004). "Sphyrna corona". The IUCN Red List of Threatened Species. IUCN. 2004: e.T44591A10910637. doi:10.2305/IUCN.UK.2004.RLTS.T44591A10910637.en. Retrieved 9 January 2018.
  2. Compagno, Leonard J. V. (1984) Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date. Rome: Food and Agriculture Organization. ISBN 92-5-101384-5.
  3. "Sphyrnidae: Sphyrna corona". Discover Life. Retrieved on October 24, 2008.
  4. Froese, Rainer and Pauly, Daniel, eds. (2008). "Sphyrna corona" in FishBase. October 2008 version.
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