Reproduction

Like all the other members of the pectinides family, the scallop is hermaphrodite and reproduces mainly during the warmest months, that is, from June to September. It's at this time of year that the coral or female gonad is particularly large. The female part of this coral tongue is orange and the male part is white. Scallops from Saint-Brieuc Bay have the specific feature that they are eaten without the coral because they are fished in winter; they are thus called "white scallops".

The scallop lays from the age of two years and produces several tens of millions of ova. The fertilization of an ovum produces a minuscule larva which has no shell, but which can swim and crawl. This larva remains in suspension in the sea for about a month, carried around by the currents. Its survival depends on temperature conditions, predators and the presence or absence of the phytoplankton which it needs to feed upon.

After other anatomical changes related to the larval phase, the juvenile scallop attaches itself to a solid body by means of its byssus, and it stays attached for several weeks until it has its adult morphology on a small scale. The scallop starts its adult life when it detaches itself from the solid object and starts to move around freely.
As regards movement, the scallop is not that badly equipped. Whereas the foot that it has is not really used much for getting about, it does have another effective technique: it opens and closes its valves, forcing water out of its shell and in this way can cover several metres when it wants to get out of the way of its predators. But once the predator is far away, it returns to being a peaceful creature sitting on the sand and feeding on plankton.