Polyclinum constellatum is a colonial encrusting tunicate. It can be grey, purplish brown or green in color, with visible white or beige systems of zooids. It was first described from Mauritius in 1816. Although this discovery suggests an Indian Ocean origin, native status in the tropical Atlantic cannot be excluded. It has been introduced to Hawaii, Guam, and the West coast of North America and is considered cryptogenic through much of its global range, including India, New Caledonia, the Gulf of Mexico, the Caribbean, Brazil and Tanzania. Polyclinum constellatum is often reported from man-made structures such as pilings, dock floats, wharfs and buoys, but is also known from natural substrates such as mangroves, dead corals and rocks. In Hong Kong, it overgrows cultured mussels, but no other economic or ecological impacts have been reported.
Image Credit: Rosana M. Rocha, Universidade Federal do Paraná (UFPR), Brazil, the grey colony.
|Bioregion||Region Name||Year||Invasion Status||Population Status|
|CAR-I||Northern Yucatan, Gulf of Mexico, Florida Straits, to Middle Eastern Florida||1887||Crypto||Estab|
|S206||_CDA_S206 (Vero Beach)||1890||Crypto||Estab|
|CAR-VII||Cape Hatteras to Mid-East Florida||1981||Crypto||Unk|
|G330||Lower Laguna Madre||2004||Crypto||Estab|
|NEP-VI||Pt. Conception to Southern Baja California||2000||Def||Unk|
|P020||San Diego Bay||2000||Def||Unk|
|PAN_PAC||Panama Pacific Coast||2008||Crypto||Estab|
|PAN_CAR||Panama Caribbean Coast||1884||Crypto||Estab|
Polyclinum constellatum is a colonial encrusting tunicate. It can be grey, purplish brown or green in color, with white or beige systems of zooids visible on the surface. The attachment area of the colony can be small, so that only a small part of the base is directly attached to the substratum (Van Name, 1945). Colonies are firm and cartilaginous, often without attached debris, but sometimes colonized by hydroids or other epifauna (da Rocha and Costa 2005). Colonies range in size from 25-65 mm long and 5-20 mm thick. The zooids of P. constellatum are about 5-7 mm long when straightened. Zooids are arranged in circular systems, of about 20 zooids each, which border a circular common cloaca (or atrial siphon). The oral siphons are tubular and fringed by six long and triangular lobes (da Rocha and Costa 2005). The reproductive organs are located in the post-abdomen, with the testes forward to the ovaries (Van Name 1945; da Rocha and Costa 2005).
Polyclinum constellatum was described from Mauritius in 1816. It is widely reported from mangroves, dead corals, rocks, and from man-made structures, such as pilings, floats, buoys, etc. (da Rocha et al. 2010; Carlton and Eldredge 2009). Although its discovery in Mauritius suggests an Indian Ocean origin, native status in the tropical Atlantic cannot be excluded. By the end of the 19th century, it was reported from the Gulf of Mexico (in 1887, Florida), the Caribbean Sea (in 1883, Jamaica), Hawaii (in 1873), and Japan (in 1900) (US National Museum of Natural History 2002; Carlton and Eldredge 2009). We consider it cryptogenic in the western Atlantic, Indian Ocean, and the western Pacific. Polyclinum constellatum is considered introduced in Guam (Lambert 2002; Lambert 2003), Tahiti (Monniot and Monniot 1985), and the Hawaiian Islands (Carlton and Eldredge 2009). It was found at the western entrance to the Panama Canal in 2002-2009 (Ruiz et al., unpublished data; Carman et al. 2010) where Carman et al (2010) considered it cryptogenic. In 2008-2009, it was found in Pacific Mexico, near Mazatlan, at the mouth of the Gulf of California (Tovar-Hernandez et al. 2010). One specimen was identfied on fouling plates in San Diego Bay in 2000 (Ruiz et al., unpublished data).
In the summer of 2000, a single specimen of Polyclinum constellatum was identified on settlement plates from Navy Pier 14 in San Diego (Ruiz et al., unpublished data). The population status of this species in southern California is not known. In 2008-2009, it was discovered further south, in the Urias estuary, near the port of Mazatlan, Mexico, and in a nearby oyster farm (Tovar-Hernández et al. 2010).
Van Name (1921; 1945) mentions the occurrence of Polyclinum constellatum on the west coast of Florida, but not on the east coast. However, Weiss (1948) found it on fouling plates in Biscayne Bay in 1944-1946. It was found in Bermuda before 1972 (Monniot 1972). Currently, it is known from waters off Georgia (in 1981, USNM 24319), the Indian River Lagoon (Mook 1983, Ruiz et al. unpublished), and Biscayne Bay (Weiss 1948; Ruiz et al., unpublished data).
The first collection of Polyclinum constellatum in US waters was in Cedar Key, Florida, in the Gulf of Mexico in 1887 (USNM 6975, US National Museum of Natural History 2010). It was collected in the Dry Tortugas in the 1880s ( USNM 7137, US National Museum of Natural History 2010, exact date unknown); Cedar Key, Florida in 1887; Tampa Bay (Gretchen Lambert 2003, personal communication); and South Padre Island, Texas in 2004 (Lambert et al. 2005). As noted above, we consider this tunicate cryptogenic in the western Atlantic.
The first Hawaiian record for Polyclinum constellatum is from Oahu in 1873 (Carlton and Eldredge 2009). Subsequently it was reported from Pearl Harbor in 1920 (Coles et al. 1999b, Carlton and Eldredge 2009); Honolulu Harbor in 1997 (Coles et al. 1999a); Ala Wai Harbor in 1998 (Coles et al. 1999a); Kaneohe Bay in 1999 (Coles et al. 2002); and Waikiki in 2001 (Coles et al. 2002). In Hawaii, this tunicate occurs on floats and pilings, but also on dead coral, and under rocks at exposed locations (Carlton and Eldredge 2009).
Polyclinum constellatum was described from Mauritius in 1816. Although its discovery in Mauritius suggests an Indian Ocean origin, native status in the tropical Atlantic cannot be excluded. Because of this uncertainty, it is considered to be cryptogenic throughout much of its global range. It was reported from Jamaica in 1883 and Japan in 1900 (US National Museum of Natural History 2002; Carlton and Eldredge 2009). Polyclinum constellatum is widely distributed throughout the Caribbean (Van Name 1945) and has also been reported from Tahiti (Monniot and Monniot 1985), New Caledonia (Monniot 1987), Tanzania (Monniot and Monniot 1997) and Brazil (da Rocha and Costa 2005). During 2009, P. constellatum was found on the Atlantic and Pacific sides of the Panama Canal (Carman et al. 2011), where Carman et al (2011) considered it to be cryptogenic.
In 1998, Polyclinum constellatum was collected on man-made substrates in Apra Harbor, Guam (USNM 25073, US National Museum of Natural History 2010; Lambert 2002; Lambert 2003) and we consider it introduced here. In 2016, it was collected from docks in two harbors on Santa Cruz Island, in the Galapagos, its first record there (Lambert 2009).
A colonial (or compound) tunicate consists of many zooids, bearing most or all of the organs of a solitary tunicate, but modified to varying degrees for colonial life. Colonial tunicates of the family Polyclinidae have zooids organized around cloacal systems. Each zooid has a thorax, an abdomen and a posterior abdomen. The thorax has an oral siphon and an atrial aperature with an anterior lip, which open to the surface. Below the thorax, the abdomen contains the stomach and intestines, while the posterior abdomen contains the ovaries, testis, and heart. Water is pumped into the oral siphon, through finely meshed ciliated gills along the pharynx, where it is filtered, and passed on mucus strings to the stomach and intestines. Excess waste is then expelled in the outgoing atrial water (Van Name 1945; Barnes 1983).
Colonial tunicates reproduce both asexually by budding and sexually from fertilized eggs that develop into larvae. Buds can form from the body wall of the zooids. Colonies vary in size ranging from small clusters of zooids to huge spreading masses. The zooids are hermaphroditic, which means both eggs and sperm are released into the atrial chamber. Eggs may be self-fertilized or fertilized by sperm from nearby animals, but some species have a partial block to self-fertilization. Eggs are brooded in the atrial chamber until they hatch into lecithotrophic (non-feeding, yolk-dependent) tadpole larvae. The larva has a muscular tail and a notochord, eyespots, and a set of adhesive papillae. The larvae are expelled upon hatching and swim briefly before settlement. Swimming periods are usually less than a day, but some larvae settle immediately after release or swim for longer periods if the water temperature is low. On settlement the tail is absorbed, the gill basket expands, and the tunicate begins to feed by filtering (Van Name 1945; Barnes 1983).
|General Habitat||Marinas & Docks|
|General Habitat||Coral reef|
|Salinity Range||Polyhaline||18-30 PSU|
|Salinity Range||Euhaline||30-40 PSU|
|Minimum Temperature (ºC)||17||Field, near southern range limit, Santa Catarina, Brazil (da Rocha et al. 2009)|
|Maximum Temperature (ºC)||29||Field, near southern range limit, Santa Catarina, Brazil (da Rocha et al. 2009)|
|Minimum Salinity (‰)||24||Field, Ilha Grande Bay, Brazil (Marins et al. 2010)|
|Maximum Salinity (‰)||40||Gulf of California, Mazatlan, Mexico (Tovar-Hernandez et al. 2010)|
|Broad Temperature Range||Warm temperate-Tropical|
|Broad Salinity Range||Polyhaline-Euhaline|
|Polyclinum constellatum was found fouling mussels (Perna perna) in an aquaculture operation in Santa Catarina, Brazil (da Rocha et al. 2009).|
|Fouling cultured shellfish in Hong Kong (Huang 2003, cited by da Rocha et al. 2009).|