Physical Description and Anatomy

Image 1: Inside of empty shells

As a bivalve mollusc, P. deltoides are comprised of two laterally flattened shells, of equal size, with bilateral symmetry (Ruppert et al., 2004). They reach sexual maturity at 3.6cm length(approximately 6 months of age) and reach a maximum of 8cm (O’Connor & O’Connor, 2011). The shells are white or bluey-white and vaguely triangular in shape. They may be tinted any number of colours; from greens and browns through creams and yellows to roseish pinks.


Image 2: Varying colours and sizes of P. deltoides

The shell is generally all you see with everything else protected inside. This is with the exception of the characteristic muscular foot that protrudes when movement such as digging is required. The foot is laterally flattened and uses blood pressure in addition to muscle contractions to move (Ruppert et al., 2004).

The diagram below shows the basic internal anatomy highlighting the recognisable and expected body components. In addition to these the mantle sits in the dorsal part of the shell with its skirts continuing around the internal shell wall (Ruppert et al., 2004). The mantle has many purposes including muscular movement, sensory, and excreting the shell layers. Internal transport occurs in a closed hemal system comprising of a basic heart and blood vessels.

P. deltoides have separate sexes and the gonads in each are a creamy or pale yellow (O’Connor & O’Connor, 2011).



FIG 2: Internal anatomy of generalised bivalve