Boom, we are coming at you with another freshwater Chondrichthyan—and it’s a shark! Known most commonly as the Speartooth shark (Glyphis glyphis), it is also called the Bizant River Shark or the Queensland River Shark.
Initially described in 2008 as Glyphis sp., it is a medium-sized whale shark with a gray dorsal side and an underbelly that reminds you of snow. With a short, round snout they have a white mouth and large pectoral fins. #Finfact: The Speartooth Shark has comparatively few teeth in comparison to other carcharhinids, with only 54 rows in both jaws (Compagno et al. 2008)! The teeth are very different in the lower and upper jaws with the top being triangular and serrated and the lower unserrated. The Speartooth Shark also has black or dusky tips on the top of their pectoral fins.
According to the species profile of the Speartooth shark by the Australia Government Department of the Environment and Energy, “the maximum recorded size of a whole specimen of the Speartooth Shark is 175 cm total length (TL) for females and 157 cm TL for males (Stevens et al. 2005). The maximum size of this species at maturity is unknown, but it is estimated that it may grow to a length of 2 to 3 m (Last & Stevens 1994).” A decently sized shark!
In Australia, they are recorded in tidal rivers and estuaries in the Northern Territory and Queensland states. In fact, scientists believe the Australian population occurs over a total area of 502 km² (the total area (km²) of each river system/estuary in which the Speartooth Shark has been found in). They have also been recorded in New Guinea and therefore is not endemic to northern Australia.
Virtually nothing is known about the biology of these sharks due to how little specimens we have. Some scientists believe they bear live young, born at about 59 cm in length. But other than that, we have no data on their size at maturity, maximum size, or how old they get! However this shark is thought to undergo migrations offshore and inshore to breed and feed. The small eyes and skinny teeth mean they probably primarily eat fish although stomach contents of one specimen showed prawns (Macrobrachium), burrowing gobies (Taenoides or Trypauchen), gudgeons (Prionobutis microps), benthic-feeding jewfish (Nibea squamosa) and bony bream (Nematalosa erebi). The main threats to the Speartooth Shark are recreational linefishing, gillnetting and habitat degradation. The IUCN has assessed them as Endangered (EN) due to how little we know about them and how restricted they are in range.
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