Black Pipis (also known as Dark Wedge-Shell or Small Mud Clam)
Phylum: Mollusca, Class: Bivalvia, Order: Venerida, Family: Cyrenidae, Genus: Batissa, Species: Batissa violacea · Cyrenidae (Marsh Clam / Mud Clam family) · Bivalve; single valve (left); Fan-shaped/Sub-triangular morphology
Species
Batissa violacea (Confidence Level: 85% based on location and morphology)
Shell Type
Bivalve; single valve (left); Fan-shaped/Sub-triangular morphology
Family
Cyrenidae (Marsh Clam / Mud Clam family)
Size
Approximately 12-18mm in length. This appears to be a juvenile specimen, as adults typically reach 50-100mm.
Color & Pattern
Deep olive-black to dark brown exterior with a thick, glossy periostracum. Near the umbo (the peak), the coating is slightly eroded, revealing a lighter, greenish-tan sub-layer. Interior is likely pearly white with violet/purple tinges near the margins.
Rarity
Common; specifically abundant in mudflat regions like those found in the Sandgate/Brighton area of Brisbane.
Habitat
Thrives in estuarine environments, brackish water lagoons, and the mouths of rivers where salt and fresh water mix. Often found buried in soft mud or fine silty sand.
Geographic Range
Commonly found in the Indo-West Pacific, significantly encompassing Northern and Eastern Australia, including the Moreton Bay region (Brisbane).
Description
A robust, sturdy bivalve with a thick, dark protective layer. The shell features concentric growth rings and a rounded-triangular shape with a prominent hinge area. Its surface is smooth but marked by fine lines reflecting its growth stages in the nutrient-rich mud.
Key Features
Ovoid to sub-trigonal shape, thick dark periostracum, characteristic erosion at the umbo, and a distinct violet-colored interior margin (which gives the species its name 'violacea').
Collector Value
Low monetary value ($1-$5) but high educational value for local biodiversity studies. Most desired when found as a matched 'doublet' (both valves joined).
Condition Notes
Good condition for a beach find. The periostracum (dark skin) is mostly intact, with minor wear at the beak. It is a single valve rather than a joined pair. Collectibility Grade: Good.
Interesting Facts
In many Pacific cultures, these clams are a traditional food source. The thick shell acts as an evolutionary defense against the fluctuating salinity and acidity of mangrove and estuarine environments.
Ecological Role
Suspension feeder that filters nutrients from the water, helping to maintain water clarity in estuaries. Serves as a primary food source for local shorebirds and rays.
Similar Species
Paphies elongata (Pipi) which is usually lighter and more elongated, or Corbiculidae species which are generally smaller and more circular.
Beach Finding Tips
Look near the tide line where the sand turns to mud or silt. Best found after a heavy rain or receding low tide at Sandgate when the estuary outflow stirs the substrate.
Notes
Brighton Sandgate beach Brisbane