Featured Species: Bigeye Sand Tiger Shark (Odontaspis noronhai)

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).

7977781531_01cc7839d9_b
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/

Family Odontaspididae contains three species of ragged tooth sharks in two genera:

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.

Untitled
Left: Lencioni, J. (Photographer). (2006). Sand Tiger Shark Carcharias taurus [Digital Image]. Retrieved from https://commons.wikimedia.org/ Center: Kerstetter and Taylor (Authors). (2008). Bigeye Sand Tiger Odontaspis noronhai [Digital Image]. Retrieved from https://nsuworks.nova.edu/ Right: NOAA (Videographer). (2017). Smalltooth Sand Tiger Odontaspis ferox [Screen Capture]. Retrieved from https://oceanexplorer.noaa.gov/

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).

Untitled
IUCN (Author) (2019). Geographic Range of Bigeye Sand Tiger Shark [Digital Image]. Retrieved from https://www.iucnredlist.org/

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.

Untitled
Left: Robertson, R.D. (Photographer). (2016). Odontaspis noronhai lateral teeth [Digital Image]. Retrieved from https://commons.wikimedia.org/ Central: Robertson, R.D. (Photographer). (2016). Odontaspis noronhai jaws [Digital Image]. Retrieved from https://commons.wikimedia.org/ Right: Robertson, R.D. (Photographer). (2016). Odontaspis noronhai central teeth [Digital Image]. Retrieved from https://commons.wikimedia.org/

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.

Odontaspis_noronhai_2
PIRO-NOAA Observer Program (Photographer). (2009). Bigeye sand tiger shark (Odontaspis noronhai) caught off Hawaii [Digital Image]. Retrieved from https://commons.wikimedia.org/

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.

Odontaspis-noronhai_Csotonyi_01_201907181314.jpg

Shark Stats

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!

_DSC2870

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/

Literature Cited

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 purposes1, 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 Science85(3), 465.

Kyne, P.M. & Ebert, D.A. (2019). Odontaspis noronhaiThe 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 relatives2, 31-56.

Next Post

Featured Species: Sicklefin Lemon Shark (Negaprion acutidens)

Previous Post

Featured Species: Viper Dogfish (Trigonognathus kabeyai)

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Powered by WordPress.com.

Up ↑

%d bloggers like this: