Houndsharks, the Triakidae, are a family of ground sharks, consisting of about 40 species in nine genera. In some classifications, the family is split into two subfamilies, with Mustelus, Scylliogaleus, and Triakis in the subfamily Triakinae, and the remaining genera in the subfamily Galeorhininae. Houndsharks are distinguished by possessing two large, spineless dorsal fins, an anal fin, and oval eyes with nictitating eyelids. They are small to medium in size, ranging from in adult length. They are found throughout the world in warm and temperate waters, where they feed on fish and invertebrates on the seabed and in midwater. Genera Furgaleus Whitley, 1951 (whiskery shark) Galeorhinus Blainville, 1816 (school shark) Gogolia Compagno, 1973 (sailback houndshark) Hemitriakis Herre, 1923 Hypogaleus J. L. B. Smith, 1957 (blacktip tope) Iago Compagno & Springer, 1971 Mustelus H. F. Linck, 1790 (smooth-hound) Scylliogaleus Boulenger, 1902 Triakis J. P. Müller & Henle, 1839 See also List of sharks References Cladogram reference Triakidae Extant Paleocene first appearances Taxa named by John Edward Gray