Pipi, Wedge Shell, or Coquina Clam
Phylum: Mollusca, Class: Bivalvia, Order: Cardiida, Family: Donacidae, Genus: Plebidonax, Species: P. deltoides · Donacidae (Wedge Shells or Bean Clams) · Bivalve (clams with two hinged shells); specimen is a single valve with a wedge or triangular shape.
Species
Plebidonax deltoides (Confidence: High)
Shell Type
Bivalve (clams with two hinged shells); specimen is a single valve with a wedge or triangular shape.
Family
Donacidae (Wedge Shells or Bean Clams)
Size
Approximately 15-20mm in length. This is a juvenile or smaller specimen, as adults in this region typically reach 40-60mm.
Color & Pattern
Pale greyish-white base with subtle brownish-grey concentric growth rings. The surface appears naturally weathered with a slight matte finish, common for beach-worn specimens found in the Brisbane/Moreton Bay area.
Rarity
Very Common. These are among the most frequently encountered shells on sandy Australian beaches.
Habitat
Coastal marine environments, specifically high-energy surf zones. They live buried just beneath the surface in the intertidal sand.
Geographic Range
Eastern and Southern Australia, ranging from Southern Queensland (including Brisbane's Brighton/Sandgate area) down to South Australia.
Description
A sturdy, smooth-surfaced bivalve valve with a characteristic wedge shape. The posterior end is short and steeply angled, while the anterior end is longer and more rounded. The texture is relatively smooth, showing fine concentric growth lines but lacking prominent radial ribs.
Key Features
Triangular 'wedge' profile, asymmetrical valves where one side is significantly shorter and flatter than the other, and a smooth, thickened hinge area.
Collector Value
Minimal monetary value (under $1), but high educational value for local biodiversity studies. They are excellent for 'reference collections' of local beach fauna.
Condition Notes
Fair to Good. The shell shows typical 'beach wear' with some erosion on the outer layer (periostracum is missing). The edges appear relatively intact, making it a decent representative specimen for a local beach collection.
Interesting Facts
In Australia, they are widely known as Pipis and are a popular food source. They are famous for their 'leaping' ability; they use a muscular foot to quickly re-bury themselves or jump when exposed by a wave.
Ecological Role
Suspension feeders that filter plankton from the water. They are a vital food source for shorebirds, rays, and various species of fish. In many areas, they are subject to strict recreational harvest limits.
Similar Species
Donax columbella (smaller, more rounded) and various Tellinidae species (usually flatter and thinner shells).
Beach Finding Tips
Look along the wash line at Brighton/Sandgate during low tide. They are often found in 'patches' where the sand remains saturated. Watch for them 'popping' out of the sand as waves recede.
Notes
Brighton Sandgate beach Brisbane