Carijoa riisei (Duchassaing & Michelotti, 1860)

Snowflake coral

Phylum Cnidaria
Class Anthozoa
Subclass Octocorallia
Order Telestacea
Family Clavulariidae

Description
The species forms erect, branching colonies with flexible stems. Each tall axial polyp has many short lateral polyps. Polyps, when extended, have eight white frilly tentacles, like the rays of a snowflake. The long stems or branches of the octocoral are a dirty white color, but they are almost always covered with a very thinly encrusting orange-red sponge, yet to be identified. Two types of sclerites occur in the body wall.
Habitat
Most commonly found in the fouling community of harbors, usually on pier pilings or wrecks which are not exposed to direct sunlight. It is found outside of harbors, especially along the leeward coast of Oahu, on shipwrecks or in sheltered and shaded crevices or shallow caves on the deeper reefs.
Distribution
Hawaiian Islands
Throughout the main Islands
Native Range
Western Atlantic, from Florida to Brazil
Present Distribution
Western Atlantic, Hawaiian Islands, possibly now widespread in the Indo-Pacific (see Remarks)
Mechanism of Introduction
Unintentional, most likely as fouling on ships' hull
Impact
Fouling organism. Ecological impact unstudied, but probably some competition for space with other invertebrates.
Ecology
Feeding
Like all cnidarians, C. riisei has tiny stinging cells in their tentacles which enable the capture of motile zooplankton.
Reproduction
Polyps may reproduce asexually by simply splitting in two, or sexually by release and fertilization of gametes into the water column. The resulting planula larvae settle to the bottom and develop directly into young polyps.
Remarks
This orange soft coral or "snowflake coral" native to the western Atlantic Ocean from Florida to Brazil, was first found in 1972 in the fouling community in Pearl Harbor (Thomas, 1979, as Telesto riisei). Muzik (pers. comm.) noted that a species of Carijoa is now also known from Chuuk, Palau, the Philippines, "Indonesia", Australia, and Thailand: whether some of these also represent the species riisei is not known, although it could certainly have achieved such a wide distribution in more than 20 years of ship-mediated dispersal if it were first introduced to the Hawaiian Islands in the late 1960s or early 1970s. Colin and Arneson (1995) published photographs of Carijoa sp. from Chuuk, in Micronesia, and from a cement ship in Enewetak, Marshall Islands, noting that "it is a very common fouling organism found on buoys, wharves and ship bottoms, plus turbid water reefs."
References
Colin, P.L. and L.Arneson. 1995. Tropical Marine Invertebrates. Coral Reef Press, Beverly Hills. 296 pp.
Thomas, W.J. 1979. Aspects of the micro-community associated with Telesto riisei, an introduced alcyonarian species. MS Thesis, Zoology Dept., University of Hawaii.