Page 80 - Invasive_Species_2013

Mediterranean invasive species factsheet

MOLLUSCS

Reproduction Common name: Spiny oyster

identification

Scientific Name:
Spondylus spinosus
Picture

Key identifying features
Brief history
Adults can be up to 12 cm in width. The lower valve
is cemented very firmly to a hard surface and is more Radial ribs with white
strong spines
cup-shaped. The upper valve is rather flat and
covered with fine short spines, which gradually
become longer and arranged in rows close to each
other. The outline of the shell is oval and irregular.
The interior of the shell, where the two valves
connect, has two teeth of equal size on each side. individuals per square metre and often can be found
The external colour of the shells is purple, brick-red, together with another alien bivalve, Chama pacifica.
red-brown or orange-brown, while the hinge area is
white with dark spots. The interior is white, becoming
Reproduction
darker (beige) in the hinge area.
The size at first reproduction of the spiny oyster is 30
mm shell length. In the eastern Mediterranean,
Field identification signs and habitat gonad development began when seawater
The spiny oyster occurs on rocky bottoms at depths temperature was ~20°C and spawning take place at
of 2–40 m. It can form large populations of up to 15 ~27°C (June-August).

Spondylus spinosus. Photo: Guido and P. Poppe Spondylus spinosus. Photo: F. Favero

Monitoring Marine Invasive Species in Mediterranean MPAs: A strategy and practical guide for managers 77