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The Diet and Dentition of Isistius brasiliensis, with Remarks on Tooth Replacement in Other Sharks
Donald W. Strasburg
Vol. 1963, No. 1 (Mar. 30, 1963), pp. 33-40
Stable URL: http://www.jstor.org/stable/1441272
Page Count: 8
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Twenty-two central Pacific specimens of the pelagic shark Isistius brasiliensis were captured by midwater trawls and plankton nets operated at night. Eight specimens were dissected; their anatomy was typically squalid and their diet consisted principally of squid. Some stomachs contained swallowed mandibular teeth in quantities sufficient to indicate that the entire mandibular dentition was shed as a unit. One Isistius had both the displaced and replacement dentitions in place in the lower jaw. Tooth measurements suggested that there are 15 complete replacements of the mandibular dentition in the known length range of Isistius, 140-501 mm. There appeared to be a decrease in the number of mandibular teeth with growth. The dried jaws of 13 other shark species were examined to determine how tooth replacement takes place. One species resembled Isistius in that it replaced all of its teeth at the same time, others constantly replaced a few teeth, while still others constantly replaced most teeth. Sometimes there were different replacement rates for the upper and lower jaws. The manner of tooth arrangement may result in some teeth blocking the replacement of others. The effects of various tooth arrangements on replacement are discussed.