Black patches of Pygmy Lichen on seashore rocks

Often mistaken for short tufts of seaweed, Pygmy Lichen – Lichina pygmaea (Lightfoot) Agardh – can easily be overlooked on the seashore. You can see it here, as a dark irregular patch in the middle of the picture, growing on a barnacle-encrusted rocky ledge called Bran Point at Ringstead Bay. Around the black lichen, small pools drying out in the sun provide a habitat for olive-coloured microscopic algae, pink encusting calcareous sponge and small Coral Weeds. 

Previously, I have described other smooth and encrusting lichens in the intertidal zone (see Why are cliffs striped at Worms Head?) In common with Verrucaria maura and Verrucaria mucosa, Pygmy Lichen is black. However, unlike these species which form a thin continous smooth layer on the rock, the Pygmy Lichen is branched, tufted, and moss-like. It is also brittle and hard to the touch.

I hope that you can see the short tufts of the lichen in the photograph below. [It was extraordinarily difficult to get a decent shot – not least because it was really uncomfortable to crawl on the rough sharp surface of the ledge.]

Black patches of Pygmy Lichen on seashore rocks

Pygmy Lichen prefers the very top of the intertidal zone around the high water mark. It may occur elsewhere in Ringstead Bay but be obscured by weed. On Bran Point ledge it shows up in marked contrast to the lighter barnacles where weed is absent. It is also easier to see when viewing along the rock platform towards the cliff. I am uncertain whether it actually prefers to colonise the seaward aspect of the raised mounds – as illustrated in the photograph below – or whether the effect of the bright light and dark shadows makes it impossible to distinguish on the landward surfaces of the hummocks.

Black patches of Pygmy Lichen on seashore rocks

Below is a shot of Bran Point rock platform looking seawards and sunwards showing how difficult it was to discern any patches of Pygmy Lichen from this direction.

Black patches of Pygmy Lichen on seashore rocks

A Post from the Past [2009]

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