This week’s Featured Species is a deep sea shark that we still don’t know much about. The crocodile shark (Pseudocarcharias kamoharai) is a member of the order Lamniformes and is the only member of its family Pseudocarchariidae (Skomal, 2016; Parker, 2008). It is the smallest of the Lamniformes sharks, measuring only 3.6 feet (1.09 m) when fully grown. They are a cigar-shaped shark with a conical, or cone shaped, snout and large eyes to gather light in the depths (Tricas, et al., 1997).
The crocodile shark is found throughout the Atlantic, Pacific and Indian Oceans in temperate to tropical waters. Despite a global distribution, a recent study of mitochondrial DNA from 255 individuals revealed a lack of regional population structure (da Silva Ferrette, et al., 2015). Combined with a high gene flow between the Atlantic and Indian Ocean individuals suggests that the crocodile shark may have a single, global population with a single gene stock (da Silva Ferrette, et al., 2015).
The crocodile shark was named as such for their prominent, long, narrow cusped teeth (Stevens, 1997). Their teeth have evolved to hunt slippery, midwater prey like squids, shrimps, and lanternfishes (Tricas, et al., 1997). Their teeth are similar in form and function to their cousin the mako shark (Isurus oxyrinchus) (Tricas, et al., 1997). Crocodile sharks venture up towards the surface at night to feed, and return to the inky depths during the day (Compagno & Musick, 2009). This daily rise and fall through the water column is known as vertical migration.
It is during their night time trips to the surface that crocodile sharks are sometimes caught as bycatch by longline fisheries industries. As the longline fisheries expands into deeper waters and further from shore, these sharks may be vulnerable to over exploitation (Compagno & Musick, 2009). Unlike large shark species that are prized for their fins, the crocodile shark is too small for their fins to be of much value, and their meat is rarely utilized (Compagno & Musick, 2009). It has been suggested that due to their low fecundity- with females only producing 4 pups at a time- and their probable demography, the crocodile shark may be reassessed as Threatened in the near future (Fowler & Cavanagh, 2005).
I’m delighted to announce a partnership with the wonderfully talented Julius Csotonyi! Julius creates stunning shark coloring sheets that are fun and educational for all ages. From time to time you’ll see Julius’ work featured right here and on my other social media platforms! You can find more coloring sheets in the store! You are welcomed to download these beautiful sheets and enjoy them with family and friends.
Authority: Matsubara, 1936
Family: Pseudocarchariidae, 1 species
Length: Maximum length 3.6 feet ( 1.09 m)
Weight: Maximum weight unknown
Habitat: Oceanic waters
Depth: Surface down to 2,000 feet (610 m)
Litter Range: Oviphagous; 4 pups per litter
Home Range: Worldwide in tropical waters
Diet: Bony fishes and invertebrates
IUCN: Near Threatened; taken by commercial fisheries as bycatch; population status unknown
(Compagno & Musick, 2009; Skomal, 2016)
Thank you for checking out this week’s featured species. Be sure to check out last week’s adorable cownose ray. Want to see your favorite species featured? Leave me a comment!
The new Ocean For Sharks Shop is open! There’s handmade ocean inspired plush animals, canvas paintings, and of course my children’s book, Winifred the Wondrous Whale Shark, available in print and PDF. Be sure to stop by. Remember proceeds benefit shark research and conservation with a donation to Project AWARE!
As always, remember you can make a difference for marine ecosystems by contacting your Congress man or woman and telling them that you care about the quality of our waters! Sharks, rays, and other marine organisms cannot speak or be represented in Congress. They need your voice. Get involved and stand up for sharks. Until next time finatics!
Featured Image Source
Randall, J.E. (Photographer). (1997). Pacific fixed individual from Hawaii [Digital Image]. Retrieved from http://www.ico.iotc.org/
Compagno LJV, 1984. FAO species catalogue. Vol. 4. Sharks of the world. An
annotated and illustrated catalogue of shark species known to date. Part 1.
Hexanchiformes to Lamniformes. FAO Fisheries Synopsis No. 125 Vol. 4(1):
Compagno, L.J.V. & Musick, J.A. 2009. Pseudocarcharias kamoharai. The IUCN Red List of Threatened Species 2009: e.T39337A10204248.
da Silva Ferrette, B. L., Mendonça, F. F., Coelho, R., de Oliveira, P. G. V., Hazin, F. H. V., Romanov, E. V., … & Foresti, F. (2015). High connectivity of the crocodile shark between the Atlantic and southwest Indian Oceans: Highlights for conservation. Plos One, 10(2), e0117549.
Fowler, S. L., & Cavanagh, R. D. (Eds.). (2005). Sharks, rays and chimaeras: the status of the Chondrichthyan fishes: status survey (Vol. 63). IUCN.
Parker, S. (2008). The encyclopedia of sharks (2nd ed.). Buffalo, NY: Firefly Books Ltd.
Randall JE, 1997. Randall’s tank photos. Collection of 10,000 large-format photos
(slides) of dead fishes. Unpublished.
Romanov EV, Zamorov VV, 1994. On discoveries of the crocodile shark,
Pseudocarcharias kamoharai (Pseudocarchariidae), in the equatorial Indian
Ocean. J. Ichthyol. 34(4): 155-157.
Romanov, E. V., Ward, P., Levesque, J. C., & Lawrence, E. (2008). Preliminary analysis of crocodile shark (Pseudocarcharias kamoharai) distribution and abundance trends in pelagic longline fisheries. IOTC Working Party on Environment and Bycatch (WPEB) Bangkok, Thailand, 20-22.
Skomal, G. (2016). The Shark Handbook: The Essential Guide for Understanding the Sharks of the World. (2nd ed.). Kennebunkport, ME: Cider Mill Press.
Stevens, J. D. (Ed.). (1997). Sharks (6th ed.). New York: Facts on File.
Tricas, T. C., Deacon, K., Last, P., McCosker, J. E., Walker, T. I., & Taylor, L. (1997). The Nature Company Guides: Sharks and Rays. (L. Taylor, Ed.). Hong Kong: The Nature Company, Time Life Books.