Chondrus crispus

Chondrus crispus—commonly calledIrish mossorcarrageenan moss(Irishcarraigín, "little rock")—is a species ofred algaewhich grows abundantly along the rocky parts of theAtlanticcoasts of Europe and North America. In its fresh condition it is soft and cartilaginous, varying in color from a greenish-yellow, through red, to a dark purple or purplish-brown. The principal constituent is a mucilaginous body, made of the polysaccharidecarrageenan, which constitutes 55% of its dry weight. The organism also consists of nearly 10% dry weight protein and about 15% dry weight mineral matter, and is rich iniodineandsulfur. When softened in water it has a sea-like odour. Because of the abundant cell wall polysaccharides, it will form ajellywhen boiled, containing from 20 to 100 times its weight of water.
Chondrus crispusis a relatively small sea alga, reaching up to a little more than20 centimetres (7+3⁄4in) in length. It grows from a discoidholdfastand branches four or five times in a dichotomous, fan-like manner. The morphology is highly variable, especially the broadness of the thalli. The branches are 2–15 mm broad and firm in texture, and the color ranges from bright green towards the surface of the water, to deep red at greater depths.Thegametophytes(see below) often show a blueiridescenceat the tip of the frondsand fertile sporophytes show a spotty pattern.Mastocarpus stellatus(Stackhouse) Guiry is a similar species which can be readily distinguished by its strongly channelled and often somewhat twisted thalli.
Irish moss undergoes analternation of generationlifecycle common in many species of algae. The two distinct stages are the sexualhaploidgametophytestage and the asexualdiploidsporophytestage. In addition, a third stage – thecarposporophyte– is formed on the female gametophyte after fertilization. The male and female gametophytes produce gametes which fuse to form a diploid carposporophyte, which formscarpospores, which develops into the sporophyte. The sporophyte then undergoesmeiosisto produce haploid tetraspores (which can be male or female) that develop into gametophytes. The three stages (male, female, and sporophyte) are difficult to distinguish when they are not fertile; however, the gametophytes often show a blue iridescence.
Chondrus crispusis commonly found along the shores of Ireland and the coast of Europe includingIceland, theFaroe Islands,westernBaltic Seato southern Spain.It is found on the Atlantic coasts of Canadaand recorded from California in the United States to Japan.However, any distribution outside the Northern Atlantic needs to be verified.
There are also other species of the same genus in the Pacific Ocean, for example,C. ocellatusHolmes,C. nipponicusYendo,C. yendoiYamadaetMikami,C. pinnulatus(Harvey) Okamura andC. armatus(Harvey) YamadaetMikami.
Chondrus crispusis found growing on rock from the middle intertidalzoneinto the subtidal zone,all the way to the ocean floor.  It is able to survive with minimal sunlight.
C. crispusis susceptible to infection from theoomycetePythium porphyrae.
C. crispusis an industrial source ofcarrageenancommonly used as a thickener and stabilizer in milk products, such asice creamand processed foods.In Europe, it is indicated asE407or E407a. It may also be used as a thickener in calico printing and paper marbling, and forfiningbeer.Irish moss is frequently used withMastocarpus stellatus(Gigartina mamillosa),Chondracanthus acicularis(G. acicularis), and otherseaweeds, which are all commonly found growing together. Carrageenan may be extracted from tropical seaweeds of the generaKappaphycusandEucheuma.
C. crispus, compared to most otherseaweeds, is well-investigated scientifically. It has been used as a model species to studyphotosynthesis, carrageenanbiosynthesis, and stress responses. Thenuclear genomewas sequenced in 2013.The genome size is 105Mbpand is coding for 9,606 genes. It is characterised by relatively few genes with very fewintrons. The genes are clustered together, with normally short distances between genes and then large distances between groups of genes.