General Description

Erect fronds appear as long hollow tubes (terete) arising from base, with occasional constrictions and compression. Fronds taper at base and at tip (apex). Unbranched. Crustose form can appear disc-like to irregular on substratum with a single layer of cells at margins (monostromatic). Holdfast at base is disc-like. Medium to dark brown. Up to 30 cm long (thallus).

Biology

The life cycle of this alga includes an alternative stage that appears as a crust during summer. The crust is often referred to as 'Ralfsia' because it was discovered on Southern Australian shores and thought to be an entirely different species Ralfsia clavata, until its life cycle was studied. The crust life stage is an important food source for intertidal snails such as limpets. The erect life cycle phase usually occurs during winter.

Habitat

Mid intertidal to shallow subtidal areas in moderate to rough waters.

Reefs

Coastal shores

Distribution guide

Worldwide.

Species Group

Seaweeds and seagrasses › Brown algae

Depth

Shore (0-1 m)
Shallow (1-30 m)

Water Column

On or near sea floor

Max Size

30 cm

Diet

Photosynthetic - sunlight

Commercial Species

No

Global Dispersal

Recorded in Australia

Identify

• Seaweeds and seagrasses

Conservation Status

• DSE Advisory List : Not listed
• EPBC Act 1999 : Not listed
• IUCN Red List : Not listed