This week’s featured species is one of three species of shark in the family Odontaspididae, commonly referred to as the ragged tooth sharks. The Bigeye Sand Tiger Shark (Odontaspis noronhai) is a large bodied shark, typically reaching lengths around 12 to 14 feet (3.6 to 4.27 m) (Ebert, Fowler, & Dando, 2015). They are found in deep waters between 1968 – 3280 feet (600 – 1,000 m) along the bottom of continental and island slopes. Well adapted to these deep water habitats, they have large eyes and uniformly dark coloring with a single white splotch on the top of the first dorsal fin (Ebert, Fowler, & Dando, 2015).
Family Odontaspididae contains three species of ragged tooth sharks in two genera:
- Sand Tiger Shark (Carcharias taurus)
- Smalltooth Sand Tiger Shark (Odontaspis ferox)
- Bigeye Sand Tiger Shark (Odontaspis noronhai)
The bigeye sand tiger shark is easily distinguished from the other two members in this family by their uniform dark red-brown to black coloring. While both the sand tiger and the smalltooth sand tiger are typically sandy brown to olive above with lighter bellies and often have splotches or spots dorsally. The bigeye sand tiger also resides in waters much deeper than either the sand tiger or smalltooth sand tiger species. Therefore, they have incredibly large eyes to utilize as much light as possible in their dim environments (Compagno, 2001). Based on these distinctions, you may think that the bigeye sand tiger has the most variation from the other two members of this family; however, it has long been debated whether the bigeye and smalltooth sand tigers should be in the same family as the superficially similar sand tiger shark Carcharias taurus. A 2012 molecular phylogenetic analysis, based on mitochondrial DNA, concluded that the bigeye sand tiger and the smalltooth sand tiger sharks were sister species;. But the results also concluded that Odontaspis and Carcharias did not share similar ancestry. Surprisingly, the bigeye sand tiger and the smalltooth sand tiger sharks were more closely related to the crocodile shark (Pseudocarcharias kamoharai), suggesting that it and Carcharias should be placed in separate families (Naylor, Caira, Jensen, Rosana, Straube, & Lakner, 2012). At the time of this writing, the family as one, but that may change in the future.
The bigeye sand tiger shark has been documented in patchy regions throughout the Atlantic, central Pacific, and Indian oceans in tropical and subtropical regions. They are known from a small number of encounters with limited records due to their deep water preferences (Kerstetter & Taylor, 2008). It is possible these sharks are widespread globally throughout the subtropics and tropics. It’s dark coloring suggests that the bigeye sand tiger spends most of its time in the mesopelagic zone. Whether this species performs vertical or horizontal migrations is still unknown. At present, further research is needed to determine their population size and structure, the entirety of their distribution, as well as population trends (Kyne & Ebert, 2019).
The bigeye sand tiger shark, like other odontaspid sharks, feed on slippery bony fishes and squids. These sharks have teeth that are well adapted to grasping their prey and swallowing them whole (Compagno, 2001). Each tooth has a narrow central cusp which is flanked by a single small cusplet on each side (Compagno, 2001). Their cousin the smalltooth sand tiger has two or three cusplets on each side of a tall, narrow central cusp.
At present time, the bigeye sand tiger shark is categorized as a species of Least Concern by the International Union for the Conservation of Nature (IUCN). Due to their natural preference for the mesopelagic zone, interactions with fishing gear is limited (Kerstetter & Taylor, 2008). This species is also rarely taken in fisheries; however, they have been documented as bycatch in pelagic gillnets, purse seines, on longlines, and in line and net gear fisheries (kyne & Ebert, 2019). They are likely utilized locally for their meat and jaws when they are caught, and their fins are likely sold in the Far East fin trade; however, documentation is very limited (Kyne & Ebert, 2019). Global monitoring of the bigeye sand tiger shark’s landing data, as well as the catch and discard data are needed to continue to support development of population assessments and potential management plans.
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: Maul, 1955
Family: Odontaspididae, 3 species in 2 genera
Length: 14.0 feet (4.27 m)
Weight: 190 lbs (86 kg)
Habitat: Midwater in open ocean; found along the bottom on continental and island slopes
Depth: 1968 – 3280 feet (600 – 1,000 m)
Reproduction: Viviparity with oophagy
Gestation: Exact gestation period unknown; 2 year reproduction cycle suspected
Litter Range: 2 pups
Home Range: Tropical and subtropical Atlantic and Pacific, possibly wide spread through tropics and substropics of Indo-Pacific
Diet: Bony fishes and squid
IUCN Status: Least Concern Globally
(Ebert, Fowler, & Dando, 2015; Kyne & Ebert, 2019)
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. Proceeds benefit shark research and conservation with a donation to Project AWARE!
Thanks so much for checking out the elusive bigeye sand tiger shark! If you missed last week’s featured species, please be sure to check out the bizarre and alien Viper Dogfish! If there is a species of elasmobranch you’d love to know more about, leave me a comment or send me a message! I would love to do a feature on your favorite species. Also connect with me on Instagram and Facebook for even more elasmo fun!
Conservation legislation needs public support in order to become law and help protect the environment and wildlife. Tell your representatives that you care about environmental and wildlife conservation. It only takes a moment to make a change that will last a lifetime. Until next time finactics!
Featured Image Source
Kerstetter and Taylor (Authors). (2008). Bigeye Sand Tiger Odontaspis noronhai captured and released in western North Atlantic in March 2008, showing hooking location and gross anatomy of head [Digital Image]. Retrieved from https://nsuworks.nova.edu/
Compagno, L. J. (2001). Sharks of the world. An annotated and illustrated catalogue of shark species known to date, vol 2. Bullhead, mackerel and carpet sharks (Heterodontiformes, Lamniformes and Orectolobiformes). FAO species catalogue for fishery purposes, 1, viii+-1.
Ebert, D. A., Fowler, S. L., & Dando, M. (2015). Sharks of the world: a fully illustrated guide. Wild Nature Press.
Kerstetter, D. W., & Taylor, M. (2008). Live release of a bigeye sand tiger Odontaspis noronhai (Elasmobranchii: Lamniformes) in the western north Atlantic Ocean. Bulletin of Marine Science, 85(3), 465.
Kyne, P.M. & Ebert, D.A. (2019). Odontaspis noronhai. The IUCN Red List of Threatened Species. Retrieved from https://www.iucnredlist.org/species/39336/2899894
Naylor, G. J., Caira, J. N., Jensen, K., Rosana, K. A., Straube, N., & Lakner, C. (2012). Elasmobranch phylogeny: a mitochondrial estimate based on 595 species. Biology of sharks and their relatives, 2, 31-56.