Page 68 - Invasive_Species_2013

Mediterranean invasive species factsheet

MOLLUSCS

Reproduction Common name: jewel box oyster

Radial rows of numerous
spines
identification

Scientific Name:
Chama pacifica
Picture

Key identifying features
Brief history
A large ovoid-shaped oyster that can grow to about
8–10 cm in length. The shell is usually thick and Interior of lower valve
irregularly rounded. The valves are different sizes, without a denticulate furrow
the lower one usually being larger and deeper than
the upper, which is usually flat.
The external valve surface bears short spines that
curve out from the surface and are larger and more
(Spondylus sp.) on bare rocks where it attaches tightly
prominent on the larger valve near the shell margin.
to the substrate with one valve. Fouling organisms
The internal margin of the shells is encircled by a rim
often attach to the shells. It has a low tolerance to
of close, fine ridges that look like a zip fastener. The
salinity changes, particularly low salinity.
external colour is highly variable, from white to
pinkish-red with pale-rose blotches around the shell
margin; the spines are often white. Reproduction
Sexes are separate and fertilization is external.
The jewel box oyster has a single, annual,
Field identification signs and habitat temperature-dependent spawning season, usually
Chama pacifica occurs on rocky shores and hard occurring during spring and summer when the
substrates, usually on exposed sites from the intertidal water temperature is higher than 21 °C. This
zone down to a few metres’ depth, occasionally to prolonged spawning period partly contributes to the
40 m. It is able to thrive in harbour environments and success of the species in new environments. Eggs
is usually found together with other oysters hatch as free-swimming planktonic larvae.

Chama pacifica. Photo: D. Riek

Monitoring Marine Invasive Species in Mediterranean MPAs: A strategy and practical guide for managers 65