How to identify seaweed

Seaweeds require enough light to photosynthesise, so are most abundant in the intertidal zone – especially along rocky shores. Here are 12 for you to spot. 

purple-larver_Dan-Cole_The-Art-Agency-08ad087

All illustrations by Dan Cole / The Art Agency 

Advertisement
1

Purple laver Porphyra umbilicalis (above

Small and purple, with broad, tough fronds. Found in upper zone of rocky shores. Edible; eaten as laver bread.

2

Oarweed Laminaria digitata

oar20weed_Dan20Cole_The20Art20Agency-5f7b3af

A glossy, golden-brown kelp up to 2m long, with distinctive ‘fingers’ on broad fronds. Exposed at low tide.

3

Furbelows Saccorhiza polyschides

furbelows_Dan20Cole_The20Art20Agency-6ac0fa6

A brown kelp with a frilled stem and large bulbous holdfast that attaches to rocks. Revealed at low spring tides.

4

Bladderwrack Fucus vesiculosus

bladderwrack_Dan20Cole_The20Art20Agency-1790b0f

Olive-brown and up to 2m long, with air bladders at the frond ends. Forms beds in mid-zone of rocky shores.

5

Channelled wrack Pelvetia canaliculata

channelled20wrack_Dan20Cole_The20Art20Agency-e564013

Brown and up to 15cm long, with fronds that curve inwards to create a channel. Found at top of the shore.

6

Pepper dulse Osmundea pinnatifida

pepper20dulce_Dan20Cole_The20Art20Agency-d624346

Small, red or brown, fern-shaped seaweed of sheltered rocky coves. Edible; used as a curry-like spice.

7

Coral weed Corallina officinalis

coral20weed_Dan20Cole_The20Art20Agency-6c5a946

Small, pink or purple seaweed with a feathery structure. Forms a dense carpet in pools on rocky shores.

8

Carrageen Chondrus crispus

carragheen_Dan20Cole_The20Art20Agency-f5d3401

Purple, with flat fronds up to 20cm long. Found on rocks on lower shore. Edible; used as a thickening agent.

9

Sugar kelp Saccharina latissima 

Sugar20kelp_Dan20Cole_The20Art20Agency-cdcdbfd

A brown kelp up to 2m long, with frilly fronds. Found below low-tide mark. Edible; used as a sugar substitute.

10

Gut weed Enteromorpha intestinalis

gut20weed_Dan20Cole_The20Art20Agency-3ab9786

Green, grass-like seaweed with tubular fronds. Found on rocks, sand or mud at all levels of the shore.

11

Velvet horn Codium tomentosum

velvet20horn_Dan20Cole_The20Art20Agency-56100b3

Green seaweed with spongy texture resembling deer antler ‘velvet’. Found in rockpools and on lower shore.

12

Sea lettuce Ulva lactuca

sea20lettuce_Dan20Cole_The20Art20Agency-a0c27f7
Advertisement

Small and green, with crumpled, lettuce-like fronds. Grows on rocks in mid-zone of shores. Edible.