A smallish brown ‘wrack’ seaweed, Channelled wrack can be recognised by the obvious ‘channels’ that its frond form – produced by their sides being rolled in. Lighter-coloured, bumpy, v-shaped swellings at the ends of the fronds are its reproductive structures. It does not have air bladders.

Behaviour

A very common seaweed, Channelled wrack grows around the high water mark on sheltered, rocky shores. Living on the upper shore, it is very tolerant of desiccation and can survive for up to eight days out of the water. In fact, if it is fully submerged for too long, it may die. Channelled wrack can live for up to four years.

Size

Length: 5-15cm

Status

Common

Distribution

Common on rocky shores all around our coasts.

When to see

January to December

Facts

Channelled wrack is a hermaphrodite, so it has both male and female structures. The gametes are released in August and September from the swollen tips of the fronds (receptacles) and are fertilised externally in the water. They settle as tiny sporelings, developing through the winter.