Hook Weed

Hypnea musciformis

Hypnea musciformis


  • Long, slender branches become intertwined with each other because of hook-like projections
  • Usually red in color, but depending on the water quality can be yellow to brown
  • Can be found growing on other algae


  • High growth rate
  • Spreads by fragmentation
  • Can be found free floating when blooming
  • Washes ashore and decomposes during peak bloom in large mats, decreasing property value and beach use
  • Introduced in the 1970s for commercial aquaculture from Florida


  • Causes shift in ecosystem; what was once coral dominated is now algae dominated with low diversity
  • Habitat loss greatly affects recreational and commercial fisheries


  • Maui: Highest distribution on leeward coast; also found on windward coast
  • Oahu: Spans from Kahala to Makaha
  • Molokai: South shore
  • Northwestern Hawaiian Islands