About Dilsea carnosa (Schmidel) Kuntze
Dilsea carnosa (Schmidel) Kuntze is a large dark red alga with a flattened, somewhat leathery texture. It can reach 30 cm or more in length and up to 15 cm in width. Most often it is unbranched, though it may split. It grows from a small discoid base attached via a discoid holdfast with a short stipe. The mature blade has a compact medulla, which is enclosed by a cortex: rounded cells on the inner side, and dense radial filaments of approximately 6 cells on the outer side.
This alga grows attached to rock in the lower littoral zone, and can be found at depths of 24 m or more. Its distribution ranges from Portugal to Arctic Russia, and it is generally widespread around the British Isles, including the Shetland Isles and the Isle of Man.
For reproduction, gametangial individuals of Dilsea carnosa are dioecious, meaning male and female gametangia develop on separate plants. Male gametes, or spermatangia, grow in patches close to the edges of the fronds. Carposporangia release spores, while tetraspores, which contain four individual spores, develop near the blade margins.
