Common Echinoderms of the shore

Common echinoderms of the shore:

Echinoderms have a hard exterior or spicules and include starfish, seaurchins and seacucumbers.   When the tide is out the best place to look for echinoderms are under boulders in rock pools.

Below are images of the common species of echinoderm you may encounter whilst rock pooling in the UK:

A Common starfish (Asterias rubens) washed up on the shore. Common starfish are orange with five arms of equal proportion and lines running down the arm mid line.

Asterias rubens on under side of a boulder.

A young Seven armed stafish (Luidia ciliaris) in a rock pool of the lower shore. As their name suggests these are the only starfish to have seven arms.

Luidia ciliaris

The Spiny starfish (Marthasterias glacialis)

The Spiny starfish (Marthasterias glacialis) has a thorny appearance from which it gets its name.

The Common sunstar (Crossaster papposus) has many arms that 
radiate like a sun.

Bloody Henry Starfish (Henricia oculata)

Cushion star (Asterina gibbosa) - a squat starfish usually found under stones and boulders in rock pools.

Asterina phylactica is a squat starfish with red pigment.

A brittlestar (Ophiothrix fragilis)

Ophiothrix fragilis

A black brittle star (Ophiocomina nigra)

Smaller brittlestars (Ophiuroidea) can be difficult to identify in the field.

A featherstar (Antedon bifida)

A green seaurchin (Psammechinus miliaris) 

A green seaurchin (Psammechinus miliaris)

The remains of a sea urchin (Echinus esculentus)

A heart urchin (Echinocardium cordatum). Usually it would buried in the sand.

A seacucumber (Holothurian) appears soft but has many spicules in its skin making it an echinoderm.

Common Seaweeds of the Shore: Greens

Green seaweeds (Chlorophyta) occur across the shore and come in all shades of green which can become bleached in the sun.

Growth forms vary between filamentous branched forms, to laminar transparent sheet like forms.

There are over 100 species of green seaweed around the UK, many of which require specialized skills in taxonomy to identify. 

Below are images of some of the common species that you may encounter whilst rock pooling around the UK:

Ulva spp. have thin translucent green fronds that can be laminar sheets (sea lettuces) or be tubular (Gut weeds).  Ulva spp. occur throughout the shore and can become abundant in sheltered pools or where fresh water occurs on the shore.

Codium fragile is green with a spongy texture. It occurs in 

pools from the mid shore into the subtidal.

Cladophora spp. Comprise relatively small branched green seaweeds that occur in pools and into the subtidal. 

Tufty green seaweeds such as, Acrosiphonia arcta  occur on rock and in pools of the mid shore into the subtidal.

Greens in a shallow intertidal pool.

Common Seaweeds of the Shore: Reds

Red seaweeds (Rhodophyta) are the most diverse and species rich group of seaweeds.

Red seaweeds come in all shades from orangey red to pink and can change colour when bleached in the sun or submerged underwater.

Growth forms vary between multi-branched fronds that arise from a stipe, to laminar transparent sheet like forms, to hard encrustations. Even a single species can exhibit a range of morphologies. For example Chondrus crispus can have a flat dichotomously notched frond (not unlike a moose’s antler) or, a thin narrow dichotomously branched frond.

There are over 350 species of red seaweed around the UK, many of which require specialized skills in taxonomy to identify. 

Below are images of some of the common species that you may encounter whilst rock pooling around the UK:

Irish moss (Chondrus crispus) is brownish- red to dark red and can be iridescent in water. Growth forms vary from a flat dichotomously notched frond (not unlike a moose’s antler) to a thin narrow dichotomously branched frond.

C. crispus occurs on rock in pools of the lower shore down into the sublittoral.

Grape pip weed (Mastocarpus stellatus) is a dark brownish-red with a flat dichotomously branched frond that can have channels running down it. This species can be easily recognized from seasonal growths that occur over the frond. M. stellatus occurs on rock of the lower shore.

Chondrus crispus and Mastocarpus stellatus

Osmundea spp is brownish-red with a cartilaginous texture, the frond is branched in one plane and looks a bit like a Christmas tree. Osmundea spp occur on damp areas of rock and pools of the mid to lower shore.

Osmundea spp occurring within a crevice. 

Osmundea spp

Corallinacea crusts are one of the most conspicuous red seaweeds of the UK. Crusts form over rocks, shells and other seaweeds as if someone has covered them with pink paint. Corallinacea crusts occur beneath overhangs and understoreys, within rock pools and into the sublittoral.

Common coral weed (Corallina officinalis) looks more like a coral than a seaweed. It is pink with a brittle “crunchy” texture and many joints with pinnate branching in one plane, like a feather. The thinner weed may represent C. elongata.

Corallina spp. occurs on rock within pools and damp crevices.

Corallina officinalis

Corallina officinalis

Corallina sp

Pink plates (Mesophyllum lichenoides) is pink with flat discoid brittle fronds. It occurs on other coralinacea in the lower shore and sublittoral.

False eyelash weed (Calliblepharis jubata) is dark red with narrow blades that branch off from a main stem giving a frilled appearance. C. jubata occurs on rocks and seaweeds in pools of the lower shore.

Dumont’s Tubular Weed (Dumontia cortorta) is brownish-red with long strip like tubular fronds. It occurs on rock in pools of the lower shore and subtidally.

Red grape weed (Gastroclonium ovatum) is brownish-red with a cartilaginous texture and rice shaped branchlets. It occurs in pools of the mid and lower shore.

Red sausage weed (Lomentaria articulata) is red with a limp texture and a beaded growth form. It occurs on rock and seaweeds in shaded areas of the shore.

Lomentaria articulata

Polysiphonia spp is a dark red epiphytic weed that grows predominately on fucoids in the mid to lower shore.

Fine veined crinkle weed (Cryptopleura ramosa) is pinky red with laminar fronds that are irregularly branched with crinkly sides. It occurs on rocks of the lower shore.

Ceramium spp is red with thin cartilaginous branches that appear highly divided and have ends that form pincers. It occurs in pools of the mid to lower shore.

Sand binder (Rhodothamniella floridula) is red and forms dense turfs on sand scoured rock of the lower shore.