Royal Netherlands Institute for Sea Research


One man’s meat is another man’s poison.

A popular fish species

Plaice is an important fish both for Dutch fisheries but also for the Wadden Sea. The fishermen are after the big ones, but in the Wadden Sea we have the youngsters. The larvae hatch in the North Sea in February and then move to the shallow, rich seabed of the Wadden Sea, at which time the process of becoming a flatfish begins. The right eye moves over to the left side and this strange fish starts living on, and a little bit in, the sand. The left side is coloured and the right side is white, with both eyes on top. Young fish eat from the bottom; they are particularly keen on the siphons of the Baltic tellin, a shellfish that lives in the sand at a depth of about 10 cm. To eat, the tellin raises two siphons out of the sand, one to suck in algae and the other to blow out the sand that has been inhaled. Siphons eaten by plaice larvae regenerate, so the eating of young plaice can be likened to a cow chewing in a meadow: everything eaten will grow back! However, the siphon is never entirely renewed so in order to eat well the tellin must climb a little out of the sand.

The knot is a bird that comes to the Wadden Sea in autumn, to eat before he goes to Africa. He is particularly keen on the Baltic tellin, but his bill is not long enough to get deeper than 6 cm into the sand. He is lucky that the small plaice has eaten here before him and forced the tellin to live a little higher in the sand, where he can reach it. In this case one man’s meat is not other man’s poison at all; both animals can now eat the tellin!

Young fish are keen on the siphons of the baltic tellin.