Certain species of these ubiquitous fish produce as many as 50 offspring at a time, born alive in the sea. Others give birth to but a single embryo. The small mother, although disemboweled, continued alive for a long time and as I held it aloft, twisted and jerked powerfully, in full possession of its faculties. Other species of sharks breed more frequently and give birth to young every few weeks, the babies maturing to be thrust into a cruel world in from 3 to 6 months. Sharks never lack for razor-sharp teeth, nature having provided a wonderful system of dentition for these pantophagous feeders.
Functional teeth stand erect on the edge of the jaws in a single row.
As these teeth become worn and lost, the membrane from the inner surface moves over the edge of the jaw, carrying with it fully developed teeth of a new, secondary row. At any given time there are behind the functional row of teeth, rows in reserve of from 5 to 7 in number, lying recumbent one below the other on the inner surface of the jaw, all in reserve being covered by a broad band of membrane that extends up over them from the bases of the jaws. These are the terrible weapons which have ability to slice into the shagreen-protected hides of other sharks, when they snap out chunks just as you would take a bite out of an apple. Sand shark caught at the island of St. John, Virgin Islands. Though disemboweled, the fish is still threshing.