Limpets: Acmaea testudinalis |
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| Common Tortoiseshell Limpet Phylum: Mollusca Class: Gastropoda Sublcass: Prosobranchia Order: Archaeogastropoda Suborder: Docoglossa Family: Acmaeidae Scientic name: Tectura testudinalis Its 'valid' scientific name is Tectura testudinalis though it is also recognized by the lesser synonym Acmaea testudinalis. Tectura testudinalis is commonly known as the tortoiseshell limpet or the Atlantic plate limpet, recognized for its smooth and intricate shell design (Figure 1 and 2). It can grow to 3 cm in diameter and 1 cm in height. It has a conical shell with an anterior apex and fine, microscopic threads around the shell edge. The shell, though smooth to the eye, has fine growth ribs radiating out from the apex. The base color is dull grey, white or reddish-brown with mottled white or brown bands in a radial-net pattern. T. testudinalis lives in the rocky intertidal zone from the littoral zone through the subtidal to depths of 50m. It is found on smooth rock and in tidepools. Tortoiseshell limpets are non-homing; they show little to no home site fidelity after foraging excursions. Foraging occurs nocturnally, primarily while submersed. T. testudinalis forages preferentially on two types of encrusting algae, Clathomorphum circumscriptum and Hillenbrandia rubra, though it also eats sporelings of fucoid species, blue-green algae, and diatoms. The tortoiseshell limpet's radula is formed differently than other limpets, with fewer teeth and harder coatings (MOHS scale = 5, 3 for other gastropods). These morphological differences allow it to specialize on the crutose-coralline algae C. circumscriptum, which has tough calcareous epithallial cells. Sources: Steneck 1982; Pueschel and Miller 1996; Lord 2008; Pizzola 2008; Common Tortoiseshell Limpet 2008; Page 2005; Martinez 2008 |  Figure 1. Distinctive tortoiseshell coloration of T. testudinalis Copyright url  Figure 2. Incredibly smooth shell of T. testudinalis with a color variation Copyright url |