Mycale grandis Gray, 1867 The orange key-hole sponge Mycale grandis is an introduced sponge that is considered invasive and a potential threat to corals and reefs in Hawaiian waters. M. grandis present on the main Hawaiian Islands. It is most likely to have been introduced is native unintentionally to the Australasia-Pacific as a fouling organism Region onand ship is hulls. M. grandis is generally restricted to shallow-water fouling communities in major harbours with associated disturbed habitats. The orange-red colouring is both internal and external. It can grow as thickly encrusting to lobate-massive cushions up to 1 metre diameter and 0.5m thick or larger. The upper surfaces of large sponges show large ostia or “keyholes”, hence the common cavernous,name. The sponge’sand often surface packed is with uneven. small The ophiuroids texture is ( Ophiactisfibrous and cf. savignyifirm but) (Eldredgecompressible, and Smithand can 2001). be torn easily. The interior is M. grandis Porites compressa was first observed in Kane‘ohe’ohe Bay, in the mid Photo credit: Steve Coles (Hawaii Biological Survey) Montipora1990s, by capitata2004 it , wasthe twoobserved dominant overgrowing reef-forming the coralfinger species coral and the ‘Near Threatened (NT)’ rice coral but there are concerns that this aggressive sponge could compete (Coles & Bolick 2006). Its ecological impacts have not been studied for space with native corals and sponge species of Kane‘ohe’ohe Bay and eventually become dominant (Coles & Bolick 2007). References: Coles, S. L and Bolick, H. 2006. Assessment of invasiveness of the orange keyhole sponge Mycale armata in Kane`ohe Bay, O`ahu, Hawai`i. Final Report Year 1 prepared for Hawaii Coral Reef Initiative. 23 p. [Link] Coles, S. L. and H. Bolick (2007) Invasive introduced sponge Mycale grandis overgrows reef corals in Ka¯ne‘ohe Bay, O‘ahu, Hawai‘i . Coral Reefs (2007) 26:911 Eldredge, L. G. and C. M. Smith. 2001 A guidebook of marine introduced species in Hawaii. Bishop Click here to view archives of previous weeks’ species Museum Tech. Rep. 21 80 pp. [Link].