- Brittle seaweed with cylindrical branches 2-5 mm in diameter. Gorilla ogo grows on the reef where it forms thick intertwining mats up to 15 cm thick
- Yellowish if growing in sunny spots, dark green or brownish when grown in shaded areas
- Grows calm, protected waters such as tide pools and reef flats up to 4 m depth (12 ft.).
- Native to the Indian Ocean and South Pacific, introduced to Hawaii for aquaculture research to produce agar
- Grows quickly, forming large, thick mats over the reef, overgrowing and killing coral and other seaweeds.
- Primarily spread by fragmentation (pieces of seaweed floating to a new location). Can also be spread by people moving pieces unwittingly.
- Large amounts of algae wash ashore on beaches impacting beach use and local economy
- Prevents young, new corals and seaweeds from attaching to the bottom to grow.
- Not recognized or preferred as food for many reef dwellers
- Changes bottom habitat, does not provide larger animals with access to holes and crevices.
- Kauai: Not known to be present at this time
- Oahu: Introduced to Waikiki and Kaneohe Bay in 1974. Can be found in Kaneohe Bay and from Maunaloa Bay to Pearl Harbor. Volunteers are used to help clean some locations of this seaweed. Click here for more information: alien algae clean-up events (this should link to the Alien algae Clean-up page)
- Maui: Not known to be present at this time
- Molokai: Introduced for aquaculture some time before 2000
- Lanai: Not known to be present at this time
- Kahoolawe: Not known to be present at this time
- Big Island: First found in Hilo Harbor in 1971, now spread south along coast