Page 82 - Invasive_Species_2013

Mediterranean invasive species factsheet

MOLLUSCS

Reproduction Common name: Japanese carpet shell,
or Manila clam

Three teeth
identification

Scientific Name:
Venerupis (Ruditapes) philippinarum
Picture

Key identifying features
Brief history
The shell is formed of two valves of equal shape and
size. Three teeth are present inside where the two
valves are hinged. The shell is oval in outline, thick,
and longer than high. The shell surface shows
evident radial ribs that are more pronounced towards
the margin, while the inside shell is smooth. The
colour is extremely variable, usually cream, with
irregular brown spots and/or stripes. The internal individuals (over 2,000 per square metre) and live for
surface of the shells is often pinkish/purplish or pale several days out of the water, as it is tolerant of a
yellow/brown. Adults can reach up to 5 cm in shell wide range of salinities, oxygen concentrations and
length. temperatures.
Reproduction

Field identification signs and habitat It requires temperatures above about 12 °C to spawn
and reproduction usually occurs from June to
The Japanese carpet shell or Manila clam is a filter-
September at water temperatures of 20–23 °C. Its
feeder, generally found in estuaries and lagoons, on
larvae spend 3–4 weeks drifting in the plankton, then
sandy and muddy bottoms, from the surface to a few settle to the bottom and attach by threads to rocks or
metres’ depth. It can reach high concentrations of shells.

Ruditapes philippinarum. Photo: Junta de Andalucia Ruditapes philippinarum. Photo: L. Schroeder_www.PNWSC.org

Monitoring Marine Invasive Species in Mediterranean MPAs: A strategy and practical guide for managers 79