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The Seashore

Irish Moss (Chondrus crispus)

Chondrus crispus

Irish Moss grows to around 15 cm and the frond is flattened. As it grows so the frond branches. The colour varies but is normally a red-brown. The tips of a mature specimen has an iridescence and may also curl up.

The red algae have accessory pigments contained in cell organelles called phycobilisomes. These pigments absorb light and pass the energy via a chain reaction to the chlorophyll a for photosynthesis. The red algae are very shade tolerant, living under the kelp, and require a fraction of the light used by land plants. In fact, if the light is too intense it soon becomes bleached; the tips of Irish Moss are often white/yellow as a result. Irish Moss is not very palatable and few herbivores will graze upon it. This may cause it to dominate the smaller algae in pools.

Irish Moss form dense tufts around the base of the kelp in the lower rocky shore. Often it is in rock pools of the middle shore. A very common and widespread species around the Atlantic, North Sea and English Channel.

Similar to Mastocarpus.

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