The Atlantic Necklace Turrid
The Atlantic Necklace Turrid, Pilsbryspira monilis (Bartsch & Rehder, 1939), is a predatory gastropod, moderately uncommon on Sanibel and Captiva islands. The species reaches about 15 mm (0.6 inch); the shell is slender, brown, with small white beads forming a spiral “necklace-like” pattern (hence the scientific name of the species, monilis, meaning necklace, or string of beads, in Latin.) The Atlantic Necklace Turrid shell aperture (opening) forms an indentation at its posterior end (photo on the right, arrow). That indentation, known as the Siphonal Notch, or Turrid Notch, accommodates the anal siphon, a fold of the animal tissue that directs waste water away from the animal.
Photo on the right shows Turrid Notch (arrow). Photos by José H. Leal.