Florideophyceae | Gigartinales
Environment / Climate / Range
Epiphytic; depth range 1 - 31 m (Ref. 102164). Tropical
Indo-Pacific and Atlantic Ocean.
Length at first maturity / Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Source of protein and carrageenan; used for human consumption, as animal feed, medicine (antitumor) and as fertilizer; used as coconut manure in Brazil and West Indies (Ref. 80758); of low commercial interest internationally as carrageenan source (Ref. 82223). Hypnea plants have compounds with medical and pharmaceutical uses such as muscle relaxants and blood agglutinins (reviewed in Schenkman, 1989) (Ref. 82232). Inhabits well in rocky habitats exposed to moderate wave action, usually lodged between coral rocks in subtidal areas (Ref. 80758); found in the high subtidal or lower intertidal zones of relatively sheltered rockflats or mudflats and sandbanks, restricted to areas where persistent low water salinity was likely to be rare (Ref. 82232). Thomas Subbaramaiah (1994) reported that growth of H. pannosa in Mandapam, India was best at lower temperatures and higher salinities (Ref. 82232). In Corpus Cristi, Suva Harbour, Fiji, H. pannosa were found but not very abundant; in Nasese/Nasova (near Ratu Sukuna Road junction), Suva Harbour, Fiji, plants of H. pannosa were abundant, but fairly small. Hypnea was very stunted, being usually >50 mm in length and often covered with filamentous epiphytes. In Draunibota Island, Suva Harbour, Fiji, isolated small H. pannosa plants were found entangled with turtlegrasses, but were not abundant. The sandee lee side of Tokatoka ni Kubu Reef has scattered plants of G.maramae and H. pannosa. In Laucala Island, Suva Harbour, Fiji, attached to or entangled with the turtlegrasses were small (>100 mm) seaweed plants identified as Gracilaria maramae and Hypnea pannosa (Ref. 82232).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
Guiry, M.D. and G.M. Guiry. 2009. (Ref. 80701)
Thalli prostrate, greenish to purple, forming thick clumps of intricating branches on rocky substrate. Branches terete to slightly compressed, 1.5 to 3 mm broad. Branching irregularly alternate to opposite, forming wide angles and rounded axils. Branches divided into short stubby spines at the terminal portion; the short ultimate branchlets are characteristically stout, stubby, and spinose. Thalli up to 8 cm in height (Ref. 80758).
IUCN Red List Status (Ref. 114614)
CITES status (Ref. 94142)
Threat to humans
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Estimates of some properties based on models
): 22.7 - 29.2, mean 28.1 (based on 4511 cells; Ref. 115970