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Taxonomic name: Mycale grandis Gray, 1867 Synonyms: Common names: orange keyhole sponge (English-USA, Hawaii), orange sponge Organism type: sponge Mycale grandis is an introduced sponge that is considered invasive and a potential threat to corals and reefs in Hawaiian waters. It is generally restricted to shallow-water fouling communities in major harbours associated with disturbed habitats, but has recently been observed over-growing native corals in lagoon-patch reef communities in Kane‘ohe‘ohe Bay, O‘ahu, Hawaii. Description Mycale grandis is an orange-red brightly coloured sponge. The 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 name. The sponge's surface is uneven. The texture is fibrous and firm but compressible, and can be torn easily. The interior is cavernous, and often packed with small ophiuroids (Ophiactis cf. savignyi) (Eldredge and Smith 2001). Occurs in: coastland, marine habitats Habitat description Mycale grandis is typically restricted to shallow-water fouling communities (i.e. pier pilings, floating docks) in major harbours or on associated disturbed habitats (i.e. dredged channels and artificial lagoons). This species has also been found over-growing native coral communities in areas of Hawaii like Kane‘ohe'ohe Bay, where it grows on patch reefs in the southeast corner of the bay as well as artificial structures (Eldredge and Smith 2001; Coles and Bolick 2006). General impacts Mycale grandis is a fouling organism whose ecological impacts have not been well studied. Observations suggest that it competes for space with native sponge and coral species and threatens lagoon-patch reef communities around Hawaii where it is overgrowing two of the dominant reef-forming corals in the Kane‘ohe‘ohe Bay. (Coles et al. 2004a; Eldredge and Smith 2001). Geographical range Native range: Asia and the Australasia-Pacific Region (Hooper and Weidenmayer, 1994). Known introduced range: Hawaii and Mexico (Coles et al. 2002; and Hooper and Weidenmayer, 1994). Introduction pathways to new locations Ship/boat hull fouling: Unintentional introduction, most likely as fouling on ships' hull (Eldredge and Smith 2001). Nutrition Mycale grandis is a filter feeder, continuously circulating water through its body. Microscopic food particles are removed from the water by specialised collar cells. Digestion is intracellular (Eldredge and Smith 2001). Reproduction Like most sponges, Mycale grandis is probably capable of asexual reproduction by fragmentation but specific details regarding sexual reproduction of this species are unstudied (Eldredge and Smith 2001). Reviewed by: Steve Coles Research Zoologist Bishop Museum Hawai'i USA Principal sources: Dr. Steve Coles, Bishop Museum. 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. Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG) To contribute information, please contact Shyama Pagad. Last Modified: Thursday, 23 March 2006