The speartooth shark (Glyphis glyphis) is an extremely rare species of river shark, belonging to the family Carcharhinidae. It inhabits coastal marine waters and tidal reaches of large tropical rivers in northern Australia and New Guinea. Despite being a member of the river shark genus, it is also found in near-shore marine waters, favoring highly turbid environments over a wide range of salinities. This robustly built, gray-colored shark is characterized by a short and broad snout, tiny eyes, a relatively large second dorsal fin, and a black blotch beneath each pectoral fin near the tip. Another identifying trait is its teeth, which are large, triangular, and serrated in the upper jaw and narrow, spear-like, and serrated only near the tips in the lower jaw. Adults grow to about 2.6 m (8.5