The largest living fish is Rhincodon typus (aka Rhiniodon typus SMITH, 1828) - the Whale shark. It is a circumglobal species of tropical and warm-temperate seas. Found singly or in groups, these sharks are suction filter-feeders, preying not only on plankton, but on small crustaceans, squid and small & medium-sized fish. Highly migratory, they are known from the Western Atlantic (New York to central Brazil), Eastern Atlantic (Senegal to Angola), throughout the Indian Ocean (and Red Sea), Western Pacific (Australia to Japan) and Eastern Pacific (California to Chile). These pelagic sharks can be found not only offshore, but in coastal waters as well, often entering lagoons or coral atolls.
The whale shark is huge, usually not exceeding 13 meters, but with reports to 18 - 20 meters. It has a broad flattened head with a large terminal and transversely expanded mouth. There are numerous homogeneous small single-cusped teeth, numbering 300 files (Compagno, 1984) or more in each jaw.
The whale sharks have a fossil record extending back into the Paleogene (see: Palaeorhincodon). The teeth of the modern species' design can be traced to the Oligocene (Chandler Bridge Formation) of South Carolina (pers. obs.). During the Miocene, they are represented in the Loupian fauna of France (Cappetta, 1970) and Lee Creek (Pungo River Frm) of North Carolina. These teeth are also present in the Yorktown (Pliocene) of the later and Kent (1994) includes them in the Miocene & Pliocene (Calvert & Yorktown Frms) of Maryland and Virginia. Purdy et al (2001) noted these teeth from Pungo River (units 1 & 2) sediments but elected to identify the teeth to genus only.
The teeth are small (reaching 6 mm) with a stout (when viewed laterally) lower, and slender upper, crown. The lingual crown face is perpendicular to the basal face of the root and the labial is lingually directed. The cusp is smooth, bears a cutting-edge and its apron extends basally, down the face of the root.
The root is bilobed, labio-lingually elongated and laterally compressed. The nutrient groove is distinct, broadening labially and growing deeper lingually. A large foramen resides in posterior of the groove, and laterally, the lobe faces bear marginal foramen. The upper surface of the root has a distinct enameloid coating.
Other Web References
Bill Heim WebPage on Rhincodon typus.
Florida Museum of Natural History: