Chorda filum

Chorda filum, commonly known as dead man's rope or sea lace among other names, is a species of brown algae in the genus Chorda. It is widespread in the temperate waters of the northern hemisphere. The species also has numerous other common names related to its physical appearance. Names include mermaid's tresses, cat's gut, bootlace weed, seatwine, and mermaid's fishing line. C. filum have typically long, unbranched and hollow rope-like brown fronds about 5 mm (0.20 in) in diameter but can reach to lengths of 8 m (26 ft). The holdfast is disc-shaped. C. filum is found in sheltered marine and brackish bodies of water at depths of 5 m (16 ft). They are usually anchored to loose substrates like gravel and pebbles or other macroalgae and eelgrass. C. filum grow at an average of 17 cm (6.7 in) per month. They are annuals and die during winter.The fronds bear short colorless hairs in summer. C. filum is similar to Halosiphon tomentosus. However H. tomentosus is less common and is covered with long brown paraphyses or sterile hairs. Chorda filum is to be found in very sheltered shores.It may be common or abundant near low water and in the sublittoral to 25 m (82 ft). in mud and sand. Widespread and generally common around Ireland, Great Britain including Shetland Isles and the Isle of Man.