The Dall Wentletrap
Dall Wentletrap, Cirsotrema dalli Rehder, 1945, can reach more than 30 mm (about 1.2 inches). It has a chalky shell surface with ribs and a background pattern of spiral cords. In addition, about 2-3 thicker ribs per whorl are present in this species. Species in this genus display an outer shell layer called intritacalx, which easily wears off in older shells. Dall Wentletrap is more commonly found in deeper water. The shell on the left, measuring a little more than an inch, was collected in 2012 by Donnie Benton under the Blind Pass Bridge (between Sanibel and Captiva). Its unusual presence in shallow water may have resulted from beach nourishment efforts that took place that year. However, a second, very worn, shell of the same species was found in December 2014 on the beach near Seagrape Street (Sanibel) by Martha Phillippi.
This latter shell, measuring ¾ inch, is shown in the images on the right, assembled from photos taken by Priya Lehr. Species identifications were confirmed by Wentletrap specialist Dr. Emilio García of Lafayette, Louisiana. Photos of Dall Wentletrap, Cirsotrema dalli: from left, adult shell measuring slightly more than an inch (Photos by José H. Leal); right, juvenile shell measuring ¾ inch (Photos by Priya Lehr).