Bladder wrack

Bladder wrack

Bladder wrack ©Kirsten Smith

Bladder wrack

+ -
Scientific name: Fucus vesiculosus
This brown seaweed lives in the mid shore and looks a bit like bubble wrap with the distinctive air bladders that give it its name.

Top facts


Length: 15-100cm

Conservation status


When to see

January to December


Probably the seaweed most associated with the seashore, Bladder wrack is a common wrack seaweed which grows between the high and low water marks on rocky shores. Bladder wrack has round air bladders which allow the seaweed to float upright underwater, this helps them exhange gases and absorb nutrients when submerged. It forms dense beds on the mid shore, often together with Egg Wrack. It provides a shelter for many creatures and is a food source for others, including the Flat periwinkle.

What to look for

Bladder wrack is an olive-brown 'wrack' seaweed. It can be recognised by its strap-like, branching fronds that have air-filled 'bladders' along their length (often appearing in pairs either side of the pronounced mid-rib). The edges are not serrated.

Where to find

Common on rocky shores all around our coasts.

Did you know?

Bladder wrack was once used as a source of iodine to treat goitres. Nowadays, you're more likely to find it in your anti-ageing cream as research has found that it has anti-ageing properties!