Mermaid’s hair/gutweed Ulva intestinalis

Gutweed is a mass of bright green, inflated tubes, often with pinched-in ‘waists’ along its length. Fronds are typically unbranched.

Behaviour

Gutweed is a common seaweed found on all UK shores and in many different habitats, including rock pools, sand, mud and even shells and other seaweeds! It is often seen with bubbles of air trapped inside its long fronds which have the look of intestines, hence its name. If detached, Gutweed can create large floating masses, buoyed by the gas in their inflated tubular fronds. Dense growths of Gutweed provide shelter for many other creatures, with their moist fronds providing a low tide refuge on the high shore.

Size

Length: up to 40cm Frond width: 6-18mm

Status

Common.

Distribution

Found on all UK coasts.

When to see

January to December.

Facts

This fast-growing species reproduces quickly and can turn water green with the release of masses of gametes and spores. It is also known as Mermaids hair!

Common name

Mermaid’s hair/gutweed

Species name

Ulva intestinalis

When to see in Scotland

January to December.

Where to see in Scotland

Across Scotland.

Snorkelling can be dangerous and is done entirely at your own risk.

Information is provided free of charge; it is your responsibility to check the conditions present on the day and assess whether it is safe to snorkel.

The Scottish Wildlife Trust strives to provide accurate information but cannot accept responsibility for changes, errors or omissions.

Back to top