This week I thought we’d break a few more misconceptions about sharks! This week’s Featured Species, the Speartooth Shark (Glyphis glyphis), is an incredibly rare species that is currently listed as Endangered (Fowler & Cavanagh, 2005). The speartooth shark was first made known to science in 1839 by Muller and Helne account of a single adult individual (Compagno, White, & Last, 2008). Over the next 175 years, adult specimens eluded researchers, who managed to gain some insight into the species from juveniles. Then in 2015, CSIRO researcher Dr. Richard Pillans and his team managed to capture two adults in the Wenlock River of north Queensland, Australia (Rigby & Sexton-McGrath, 2015). Yes, you read that right, RIVER.
I’m sure you’ve probably heard at one point or another that the bull shark (Carcharhinus leucas) was the only shark that could inhabit freshwater. It is true that they have the remarkable ability to pass from marine to freshwater environments and have been found thousands of miles up the Amazon River. However, the bull shark is by no means the only shark that can and does reside in freshwater ecosystems. The speartooth sharks are make their homes within freshwater, estuarine, and inshore habitats (Compagno, et al., 2008), They have been found in the estuarine waters of Papua New Guinea and far up the Fly River (Compagno, 2002). In Australia, they have been found in the lower Bizant River in Queensland, which has also given rise to their other common name the Bizant River Shark (Compagno, 2002).
Based on their apparent rarity, the speartooth shark’s population is suspected to be small. At present time, the speartooth shark is listed by the IUCN as an Endangered species. However they are listed as Critically Endangered on the Commonwealth Environment Protection and Biodiversity Conservation Act of 1999 in Australia. They are also categorized as a Vulnerable species under the Territory Parks and Wildlife Conservation Act of 2000 (Stirrat and Larson, 2002). Because their populations are suspected to be small and the exact number and size of subpopulations is unknown, all populations are in need of protection in order to preserve genetic diversity within the species (Compagno, Pogonoski, & Pollard, 2009).
While I’m not a fan of the show, the glyphis shark was featured on River Monsters. The film crew was working with scientists in the field to attempt to catch these rare sharks, record biological information, collect DNA samples, tag them, and return them to the water as quickly as possible. This is one of the few glyphis sharks recorded on film in the wild.
Animal Planet [Videographer}. (2014 May 28). Fan Favorite: Rare Glyphis Shark Filmed | River Monsters [Video Clip]. Retrieved from https://www.youtube.com/
Authority: Müller & Henle,1839
Length: Up to 8.5 ft (2.6 m)
Weight: Maximum weight unknown
Habitat: Inshore, estuarine, and freshwater rivers.
Depth: Shallow waters
Gestation: Period unknown
Litter Range: Unknown
Home Range: Inshore, Estuarine, and Freshwater ways of Australia and Papua New Guinea. Documented in Bizant River of Queensland, Australia and the Fly River of New Guinea.
Diet: Demersal bony fishes, crustasceans
IUCN Status: Endangered
(Fowler, & Cavanagh, 2005; Compagno Pogonoski, & Pollard, 2009)
Thanks for checking out the amazing and rare glyphis river shark this week! If you missed last week’s Featured Species: the Tiger Shark, I highly recommend that you check it out. There was also an awesome press release earlier this week about hermaphroditic sharks. It’s such an interesting find, definitely worth checking out!
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
VirtualWolf (Photographer). (2011 September 11). Speartooth Shark [Digital Image]. Retrieved from https://www.flickr.com/photos/virtualwolf/6155634372
Compagno, L. J. V. (1997, July). Freshwater and estuarine elasmobranch surveys in the Indo-Pacific region: threats, distribution and speciation. In Elasmobranch Biodiversity, Conservation and Management: Proceedings of the International Seminar and Workshop, Sabah, Malaysia (pp. 168-180).
Compagno, L.J.V., Pogonoski, J. & Pollard, D. 2009. Glyphis glyphis. The IUCN Red List of Threatened Species 2009: e.T39379A10221801.
Compagno, L. J., White, W. T., & Last, P. R. (2008). Glyphis garricki sp. nov., a new species of river shark (Carcharhiniformes: Carcharhinidae) from northern Australia and Papua New Guinea, with a redescription of Glyphis glyphis (Müller & Henle, 1839). Descriptions of New Australian Chondrichthyans, 203-225.
Fowler, S. L., & Cavanagh, R. D. (Eds.). (2005). Sharks, rays and chimaeras: the status of the Chondrichthyan fishes: status survey (Vol. 63). IUCN.
Rigby, M., & Sexton-McGrath, K. (2015). Researchers capture and tag rare adult speartooth sharks for first time. Retrieved July 12, 2018, from http://www.abc.net.au/news/2015-11-11/rare-adult-sharks-captured/6930360
Stirrat, S. and Larson, H. 2002. Threatened species of the Northern Territory