Watersipora subtorquata is a widespread encrusting cheilostome bryozoan. It has a cosmopolitan distribution and is found in most areas with significant shipping traffic (See Biogeographic distribution). W.subtorquata is commonly found encrusting the hulls of ships (See Ecology). Colonies are formed from a sexually produced larvae and zooids bud asexually to extend the colony (See Reproduction & Colony Formation). Colonies are orange in life and only a few centimetres in diameter (See Physical Description).  

Watersiporia subtorquata is a colonial encrusting bryozoan (Vieira et al., 2014). Generally unilamellar and encrusting on flat substrata it can sometimes form erect foliose colonies, which can be bilamellar or mulitlamellar (Vieira etal., 2014). It varies between orange to brownish- purple in colour (Vieira etal., 2014), the colouration comes from the colour of the polypide, with the zooecium being transparent, see figure 1. The lophophore is the tentacled feeding structure at the top of the polypide. It is everted during feeding and can be retracted inside the zooecium.  The zooecium is a calcium carbonate box like structure (Hart & Keough, 2009). The lophophore in W. subtorquata has 20-22 tentacles (Viera et al, 2014). Colonies are typically up to 4cm in diameter. Zooids are typically ~ 1mm long and ~0.3mm wide (Vieira et al., 2014) 

Watersipora subtorquata is the most common intertidal bryozoan in many areas of introduction (Mackie,Keough,& Christidis, 2006). It frequently outcompetes native bryozoans and other sessile organisms (Mackie et al, 2006). Copper is used in many antifouling paints (McKenzie, Brooks & Johnston, 2012). W. subtorquata is less adversely affected by copper than many other fouling organisms, giving it a competitive advantage in the presence of copper (McKenzie et al., 2012). While presence of copper increases post-settlement mortality of W. subtorquata larvae it has been demonstrated to increase overall recruitment of W. subtorquata (McKenzie et al., 2012).

Bryozoans are preyed on by a variety of taxa, fishes, gastropds, pycnogonids, echinoids,crustaceans, chitons, asteroids and turbellarians (Lidgard, 2008). Some pycnogonids, nudibranchs, and turbellarians are thought to be specialist bryozoan predators (Lidgard, 2008). Some nudibranchs have been reported to feed only on particular species of bryozoan (Lidgard, 2008). 

Watersipora subtorquata colonies are made up of zooids. Bryozoans have no specialised gas exchange structures, gases are exchanged across the skin and in particular across the lophophore (Ruppert, Fox, & Barnes, 2004).Bryozoans have a U-shaped gut, with the mouth in the centre of the lophophore and the anus outside the ring of the lophophore (Ruppert, Fox, & Barnes, 2004).Bryozoans have no heart, they move nutrients within and between zooids via a type of circulatory system called the funicular system (Ruppert, Fox, & Barnes, 2004). The zooids are connected via the interzooidal pore and the nutrients are transferred between zooids via the rosette cells (Ruppert,Fox, & Barnes, 2004; Bone & Keough, 2010).

Bryozoan phylogeny is very poorly resolved at all levels of classification (Waeschenbach, Taylor, & Littlewood, 2012). Watersipora is placed within the family Watersiporidae, which includes the genera Uscia, Veleroa and Watersipora (Vieira,2014). Watersiporidae is placed within the order Cheilostomata (Class Gymnolaemata)(Vieira, 2014). Relationships within this order are very poorly resolved (Waeschenbach et al., 2012).

It is likely that the genus Watersipora contains more species than are currently described. Lack of morphological characters commonly used to differentiate between species of cheilostome bryozoans, such as avicularia and other heterozooids, makes misidentification of species within this genus common (Mackie et al, 2012; Viera et al, 2014). Genetic evidence suggests high likelihood of numerous cryptic species within this genus (Mackie et al, 2006; Mackie et al, 2012). The species Watersipora subtorquata is sometimes referred to as W. subtorquata species complex, due to it being considered likely to contain multiple species (Mackie et al, 2012).

Bryozoans have an extensive fossil record . Cheilostome bryozoans first appeared during the Jurassic and dominate the bryozoan fauna from the Cretaceous to the present day (Taylor & Ernst, 2008).Among cheilostome bryozoans, the degree of polymorphism within species has increased in the last 50 million years (McKinney & Jackson, 1989). It was believed that higher levels of polymorphism indicated higher levels of physiological connectedness among zooids (McKinney & Jackson, 1989), however more recent evidence suggests that this is not the case, at least not in all species (Bone & Keough, 2010). The only fossil of the genus Watersipora is a neogene fossil found in the southeastern USA called Watersiporagrandis (Vieira et al, 2014). 

Watersipora subtorquata has a cosmopolitan distribution and is common in most areas between 0˚and 40˚ latitude (Vieira et al,2014). Although there are records of it occurring at higher latitudes (Kelso & Jackson, 2012). It is believed (although not with a great deal of certainty) to have originated in the Caribbean- Atlantic region (McKenzie,Brooks & Johnston). Its spread to other regions of the world has been recorded since approximately 1960, although spread may have preceded records by a substantial amount of time (Mackie et al, 2012). W. subtorquata was first recorded in Australia in the 1970's (Mackie et al, 2006). It has likely been spread on the hulls of ships which it commonly fouls (McKenzie, Brooks & Johnston). Low genetic divergence between widely spaced populations in Australia, Florida and Brazil support the recorded evidence of recent introductions (Viera et al,2014).

Watersipora subtorquata is an invasive biofouling bryozoan. Consequently it is of no conservation concern. 

Bone, E.K.,& Keough, M.J. (2010) Does Polymorphism Predict Physiological Connectedness? A Test Using Two Encrusting Bryozoans. Biological Bulletin. 219. 220-230.

Hart, S.P., & Keough, M.J. (2009) Does Size Predict Demographic Fate? Modular Demography and Constraints on Growth Determine Response to Decreases in Size. Ecology.90(6).1670-1678.

Kelso, A., & Jackson, P.N.W. (2012) Invasive bryozoans in Ireland: first record of Watersipora subtorquata (d'Orbigny, 1852) and an extension of the range of Tricellaria inopinata d’Hondt and Occhipinti Ambrogi, 1985. BioInvasions Records.1(3). 209–214. doi: http://dx.doi.org/10.3391/bir.2012.1.3.06

Lidgard, S. (2008) Predation on marine bryozoancolonies: taxa, traits and trophic groups. Marine Ecology Progress Series. 359.117–131. doi: 10.3354/meps07322

Mackie, J.A., Keough, M.J.,& Christidis, L. (2006) Invasion patterns inferred from cytochrome oxidase I sequences in three bryozoans, Bugula neritina, Watersipora subtorquata, and Watersipora arcuata. Marine Biology. 149. 285–295. doi:10.1007/s00227-005-0196-x

Mackie, J.A., Darling, J.A.,& Geller, J.B. (2012) Ecology of cryptic invasions:latitudinal segregation among Watersipora (Bryozoa) species. Scientific Reports. 2 .871. doi:10.1038/srep00871 1

McKenzie, L.A., Brooks, R.C., & Johnston, E.L. (2012) A widespread contaminant enhances invasion success of a marine invader. Journal of Applied Ecology. 49. 767–773. doi:10.1111/j.1365-2664.2012.02158.x

McKinney, F.K. & Jackson, J.B.C. (1989) Bryozoan Evolution. Chicago: The University of Chicago Press.

Taylor, P.D. & Ernst, A. (2008) Bryozoans in transition: The depauperate and patchy Jurassic biota. Palaeogeography, Palaeoclimatology, Palaeoecology. 263.9–23

Vieira, L.M., Jones, M.S.,& Taylor, P.D. (2014) The identity of the invasive fouling bryozoan Watersipora subtorquata (d’Orbigny) and some other congenericspecies. Zootaxa. 3857 (2). 151–182. http://dx.doi.org/10.11646/zootaxa.3857.2.1

Waeschenbach, A., Taylor, P.D., & Littlewood, D.T.J. (2012) A molecular phylogeny of bryozoans. Molecular Phylogenetics and Evolution. 62. 718–735.doi:10.1016/j.ympev.2011.11.011