Mastocarpus papillatus is a distinctive red seaweed (Phylum Rhodophyta) that until the 1970s was considered to be two different species because of its two distinctive life stages.
Description:
One life stage forms a dark brown to black smooth crust, 1 to 2.5 mm thick on rocks. This stage has been referred to as 'sea tar' or 'tar spot' because it looks like spilled tar or oil. The crust is not hard; you can sink your fingernail into it.
The other life stage forms a blade that is purple to black in colour. The blade can be triangular in shape but at Tower Beach is often irregular and no more than 10 cm in length. The surface of the blade is covered in small projections similar to a towel, hence the common name 'Turkish wash cloth'. The blade is attached to rock by a small holdfast. When the tide rises and waves break on the algae the blades thrash about. It is not surprising the name Mastocarpus is derived from the Greek word for whip-like body.
The life history of Mastocarpus, like many red seaweeds is complicated. The crust stage (sporophyte) produces spores that are shed into the water and eventually settle to the bottom and develop into the blade stage. Environmental conditions trigger the development of gametes in this gametophyte generation. The gametes are shed into the water. When the gametes fuse they form the crust sporophyte generation.
The other life stage forms a blade that is purple to black in colour. The blade can be triangular in shape but at Tower Beach is often irregular and no more than 10 cm in length. The surface of the blade is covered in small projections similar to a towel, hence the common name 'Turkish wash cloth'. The blade is attached to rock by a small holdfast. When the tide rises and waves break on the algae the blades thrash about. It is not surprising the name Mastocarpus is derived from the Greek word for whip-like body.
The life history of Mastocarpus, like many red seaweeds is complicated. The crust stage (sporophyte) produces spores that are shed into the water and eventually settle to the bottom and develop into the blade stage. Environmental conditions trigger the development of gametes in this gametophyte generation. The gametes are shed into the water. When the gametes fuse they form the crust sporophyte generation.
Ecology:
Mastocarpus papillatus are found along the Pacific coast from Alaska to Mexico, usually in the mid to low intertidal regions. They can withstand wave-exposure but are also found in moderately wave-sheltered sites. They share these habitat requirements with Fucus spp. and are often found associated with them in the same intertidal regions.
To learn more:
Druehl, Louis D. 2000. Pacific Seaweeds. A guide to common seaweeds of the West Coast. Harbour Publishing, Madeira Park, B.C.
Sept. J. Duane. 1999. The Beachbomber's Guide to Seashore Life in the Pacific Northwest. Harbour Publishing, Madeira Park, B.C.
Snively, Gloria. 1978. Exploring the Seashore in British Columbia, Washington and Oregon. A Guide to Shorebirds and Intertidal Plants and Animals. Gordon Soules Book Publishers, Vancouver.
Waaland, J. Robert. 1977. Common Seaweeds of the Pacific Coast. J.J. Douglas Ltd. North Vancouver.