Exochella tricuspis


Scientific Name: Exochella tricuspis

Phylum: Bryozoa

Class: Gymnolaemata

Order: Cheilostomatida

Family: Exochellidae

Genus: Exochella


tricuspis [Describe here as A. iricolor]

Native Distribution

Origin Realm:

Temperate Austrasia, Central Indo-Pacific, Temperate Northern Pacific, Temperate Southern Africa

Native Region:

Origin Location:

Temperate Australasia [New Zealand] Tasman Bay; Goat Island Bay (Bradstock and Gordon 1983; Gordon 1972; Hayward 1991; Gordon 2007) STATUS STATED [Australia] Bass Strait; South Australia (Hayward 1991; Wass and Yoo 1983) STATUS NOT STATED [Tasmania] West coast (Wass and Yoo 1975) STATUS NOT STATED [New Zealand] Hauraki Gulf and Napier in North Island, Three Kings Islands and Cook Strait, vicinity of North Island, Foveaux Strait, south of South Island, Chatham Rise, and Kermadec Ridge. (Gordon 1984) STATUS NOT STATED [Australia] Victoria, Bass Strait. (Gordon 1984, Hayward 1991 but only described the specimen from Bass Strait) STATUS NOT STATED Central Indo-Pacific [New Caledonia] (Gordon 2007) STATUS NOT STATED Temperate Northern Pacific [Korea] Yellow Sea (Seo and Min 2009) STATUS NOT STATED [Japan] (Seo and Min 2009) STATUS NOT STATED [South Korea] Sansido Island and Jangjado Island, Gogunsan Islands (Jul 1980); Seogwipo (May 1982); Mipo (Aug 2003) (Seo and Min 2009) STATUS NOT STATED, though noted as first record for Korea [Korea] Sinsido Island, Jangjado Island, Gogunsan Islands, , and Mipo. (Seo & Min 2009) STATUS NOT STATED [Japan] [As Exochella arealata (Synonymized taxon by Seo & Min 2009)] Koshikine in Onagawa Bay, Miyagi Prefecture. (Okada & Mawatari 1937) STATUS NOT STATED Temperate Southern Africa [South Africa] Cape of Good Horp. (Gordon 1984 but Hayward (1991) questioned the record and required to reinvestigation. STATUS NOT STATED

Geographic Range:

[Western Pacific] Korea to Japan; Australia and New Zealand; New Caledonia (Seo and Min 2009; Cheetham and Sandberg 1964; Kiessling et al 2015) [Eastern Atlantic] Tasmania; South Africa (Cheetham and Sandberg 1964) [New Zealand: Kermadec Ridge] (Gordon 1984) 31°20.8'S, 178°49.2'W 29°13.31S, 177°56.34W 29°13.24S, 177°56.30W 29°13.30S, 177°59.80W 30°15.5S, 178°24.2W 31°21.25S, 178°49.25W

General Diversity:


Non-native Distribution

Invasion History:

No records of invasion (Global Invasive Species Database 2016)

Non-native Region:

Not applicable

Invasion Propens:

Not applicable

Status Date Non-native:

Not applicable

Vectors and Spread

Initial Vector:

Natural dispersal

Second Vector:


Vector Details:

Evidence of rafting on marine litter, been found on plastic debris (Kiessling et al. 2015)

Spread Rate:


Date First Observed in Japan:


Date First Observed on West coast North America:



Impact in Japan:


Global Impact:



Native Temperature Regime:

Cool temperate, Mild temperate, Warm temperate

Native Temperature Range:

11.337-24.377°C (OBIS 2015) Auckland, near Hauraki Gulf, New Zealand: max 22.4ºC in summer and min 10.5ºC in winter. (Clark et al. 2003) Kunsan, near Sinsido Island, Korea: max 24.0ºC in summer and min 3.0ºC in winter. (Clark et al. 2003) Cool temperate, Mild temperate, Warm temperate (M. Otani, pers. comm.)

Non-native Temperature Regime:

Not applicable

Non-native Temperature Range:

Not applicable

Native Salinity Regime:

Polyhaline, Euhaline

Native Salinity Range:

34.728-35.563 PPS (OBIS 2015) Auckland, near Hauraki Gulf, New Zealand: max 36.0psu in dry period and min 28.0psu in wet period. (Clark et al. 2003) Kunsan, near Sinsido Island, Korea: max 33.0psu in dry period and min 24.0psu in wet period. (Clark et al. 2003)

Non-native Salinity Regime:

Not applicable

Temperature Regime Survival:

See details

Temperature Range Survival:

11.337-24.377°C (OBIS 2015)

Temperature Regime Reproduction:


Temperature Range Reproduction:


Salinity Regime Survival:


Salinity Range Survival:

34.728-35.563 PPS (OBIS 2015)

Salintiy Regime Reproduction:

Polyhaline, Euhaline

Salinity Range Reproduction:


Depth Regime:

Lower intertidal, Shallow subtidal, Deep subtidal

Depth Range:

Sample depth 34-75m (OBIS 2015) [New Zealand] Tasman Bay, where species is found, has depths of 10-35m (Bradstock and Gordon 1983) [New Caledonia] 33-35m (Gordon 2007) Intertidal, on rocks and algae (Gordon 1972) [New Zealand] Keramadec Ridge: 10-140m. (Gordon 1984) [Japan] Koshikine, Onagawa Bay: 19m. (Okada & Mawatari 1937)

Non-native Salinity Range:

Native Abundance:



Fertilization Mode:


Reproduction Mode:


Spawning Type:


Development Mode:

Lecithotrophic planktonic larva (non-feeding)

Asexual Reproduction:

Budding/fragmentation (Splitting into unequal parts. Buds may form on the body of the “parent”)

Reproduction Details:

Ovicells present (Hayward 1991; Gordon 1972; Seo and Min 2009) RELATED: [Exochella) Other Exochella spp. has been described as having macrolecithal oocytes (Ostrovsky 2013) [Gymnolaemates] Internal fertilization, whether intracoelomic or intraovarian, is obligatory (Temkin 1994, cited in Ostrovsky 2013; Temkin 1996) [Gymnolaemates] Differ from most organisms in that sperm-egg fusion does not stimulate egg activation. Egg activation may not occur until "spawned" outside of maternal zooid (Temkin 1991) [Bryozoans] Non-brooding bryozoans feed during the larval stage, while the larvae of brooding bryozoans do not, since these larvae tend to settle soon after release (Hill 2001) [Bryozoans] While sperm is spawned through pores in lophophore tentacles, eggs are usually harbored inside the body wall, and are internally fertilized by sperm, coming in on lophophore feeding currents (Brusca and Brusca 2003, cited in Rouse 2011; Kozloff 1990, cited in Rouse 2011) [Bryozoans] Colonial hermaphrodites, with testes (spermatogenic tissue) and ovaries developing either within the same zooid (zooidal hermaphroditism) or in different zooids within the same colony (zooidal gonochorism) (Ostrovsky 2013) [Bryozoans] Members of the phylum Bryozoa are hermaphroditic. Both fertilization and egg brooding may either be internal or external (Ruppert et al. 2004) [Bryozoans] The first zooid in a colony is called the ancestrula. It is from this individual that the rest of the colony will grow asexually from the budding (Hill 2001) [Bryozoa] All bryozoan colonies are hermaphroditic. Autozooids may be dioecious; or monoecious, and protandrous or protogynous. (Hayward & Ryland 1999) [Bryozoa] Reproduces asexually by budding. (Mawatari 1976)

Adult Mobility:


Adult Mobility Details:

Encrusting species (Gordon 1972; Seo and Min 2009) RELATED: [Bryozoa] The abundance and taxonomic diversity of benthic bryozoan faunas are directly related to substratum. (Hayward & Ryland 1999) [Bryozoa] Bryozoans are a phylum of sessile, colonial suspension feeders found throughout the world in both marine and freshwater environments. (Tilbrook 2012)

Maturity Size:

Autozooids: 0.38 x 0.25mm (Hayward 1991) Zooecia: 0.25-0.29mm wide; 0.40-0.58mm long (Seo and Min 2009)

Maturity Age:


Reproduction Lifespan:




Broods per Year:


Reproduction Cues:

RELATED: [Bryozoans] Experiments often used light as a cue to collect embryos/larvae (Woollacott and Zimmer 1977) [Bryozoa] In coastal species light is an important stimulus to larval release, and many cheilostomates shed larvae during the first few hours of daylight. (Hayward & Ryland 1999) [Bryozoa] In various degrees of intensity according to the species temperature also stimulates sexual reproduction. (Winston 1977)

Reproduction Time:




Egg Size:

RELATED: [Exochella] Growing oocyte: 19.0x15.0μm; Early vitellogenic: 70.0x55.0μm; Mature oocyte: 145.0x105.0μm (Ostrovsky 2013) [Gymnolaemata] About 200µm (Woollacott and Zimmer 1977)

Egg Duration:


Early Life Growth Rate:

RELATED: [Gymnolaemata] Two phases of larvae metamorphosis: first stage about 20mins; second stage 1-6 days (Woollacott and Zimmer 1977)

Adult Growth Rate:


Population Growth Rate:


Population Variablity:




Rocky intertidal, Rocky subtidal, Coral reef, Macroalgal beds, Flotsam

Habitat Type:

Epibenthic, Epiphytic


Biogenic, Rock, Artificial substrate



Habitat Expansion:


Habitat Details:

[New Zealand] Tasman Bay described as coral-like, coral bed area (Bradstock and Gordon 1983) [New Zealand] on rocks and algae (Gordon 1972) [South Korea] Found on seaweeds (Seo and Min 2009) Collected from stranded plastic items (Kiessling et al 2015) Found associated with the bryozoans Celleporaria agglutinans and Hippomenella vellicata (Bradstock and Gordon 1983) The zoarum incrusts sea-weeds, forming a circular patch, thin and unilamellar at Koshikine, Onagawa Bay, Japan. (Okada & Mawatari 1937) Found on seaweed in Korea. (Seo & Min 2009)

Trophic Level:

Suspension feeder

Trophic Details:

RELATED: [Bryozoans] Suspension feeder...filter phytoplankton less than 0.045mm in size from the water column. (Hill 2001) [Bryozoa] Many phytoplankton species are cleary unsuitable as food for bryozoans. (Hayward & Ryland 1999) [Cheilostomata] Main food is diatom, protozoans and etc. and unappropriate sized particles are ejected (Mawatari 1976)

Forage Mode:


Forage Details:

RELATED: [Bryozoans] Suspension feeder...filter phytoplankton less than 0.045mm in size from the water column. (Hill 2001) [Bryozoa] Many phytoplankton species are cleary unsuitable as food for bryozoans. (Hayward & Ryland 1999) [Cheilostomata] Main food is diatom, protozoans and etc. and unappropriate sized particles are ejected (Mawatari 1976)

Natural Control:

COMPETITION: Competition for space between species and other colonies (Gordon 1972) RELATED: PREDATION [Predation] [Bryozoa] Browsers and grazers, including sea urchins, fish, crabs and some prosobranchs, are known to include bryozoans in their diet. (Hayward & Ryland 1998) [Predation] [Bryozoa] Bryozoans are also the prey of very many small, selective predators, some of which may be adapted to a very narrow spectrum of prey species. Among them opisthobranch predators of bryozoans are well known. (Hayward & Ryland 1998) [Predation] [Bryozoa] Other than opisthobranchs as a predator, amphipods, isopods, mites and pycnogonids have all been recorded preying on bryozoan colonies. (Hayward & Ryland 1998) EPIBIONTS [Epibionts] [Cheilostomata] It is frequently observed in Japan that several species of hydroids flourish on Cheilostomata cause damages to them. (Mawatari 1976)

Associated Species:


References and Notes


Bradstock, M., & Gordon, D. P. (1983). Coral‐like bryozoan growths in Tasman Bay, and their protection to conserve commercial fish stocks. New Zealand Journal of Marine and Freshwater Research, 17(2), 159-163. Doi: 10.1080/00288330.1983.9515993 Cheetham, A. H., Sandberg, P. A. (1964). Quaternary bryozoa from Louisiana mudlumps. Journal of Paleontology, 38(6), 1013-1046. Clarke C, Hillard R, Junqueira AOR, Neto ACL, Polglaze J, Raaymakers S (2003) Ballast water risk assessment, Port of Sepetiba, Fedral Republic of Brazil. GloBallast Monograph Series 14: 1-63 + 7 Appendices. Global Invasive Species Database. http://www.iucngisd.org/gisd/ Access Date: 14-Mar-2016. Gordon, D. P. (1972). Biological Relationships of an Intertidal Bryozoan Population. Journal of Natural History, 6(5), 503-514. Doi: 10.1080/00222937200770461 Gordon DP (1984) The marine fauna of New Zealand: Bryozoa: Gymnolaemata from the Kermadec Ridge. New Zealand Oceanographic Institute Memoir 91: 1-198. Gordon, D. P. (2007). Bryozoa of New Caledonia. In C. E. Yayri & B. Richer de Forges (Eds.), Compendium of marine species of New Caledonia, Doc. Sci. Tech. II7, seconde édition (pp. 157-168). IRD Nouméa Hayward, P. J. (1991). Systematic studies on some Antarctic and sub-Antarctic Ascophora (Bryozoa: Cheilostomata). Zoological Journal of the Linnean Society, 101(4), 299-335 Hayward PF & Ryland JS (1999) Cheilostomatous Bryozoa part 2. Hippothooidea - Celleporoidea. Synopses of the British Fauna (New Series). Barnes RSK & Crothers JH (eds.) No. 14 (Second Edition). The Linnean Society of London and The Estuarine and Coastal Sciences Association by Field Studies Council: 416pp. Hill, K. (2001) Smithsonian Marine Station at Fort Pierce. Retrieved from http://www.sms.si.edu/irlspec/Electr_bellul.htm Kiessling, T., Gutow, L., & Thiel, M. (2015). Marine Litter as Habitat and Dispersal Vector. In M. Bergmann, L. Gutow, & M. Klages (Eds.), Marine Anthropogenic Litter (pp. 141-181). Springer International Publishing Mawatari S (1976) Bryozoa (Ectoprocta). In: Animal systematics. Uchida T (ed.) Nakayama-shoten Co. Ltd., Tokyo: 35-229. (in Japanese) OBIS. (2015). Ocean Biogeographic Information System. Retrieved from http://iobis.org/mapper Okada Y & Mawatari S (1937) On the collection of Bryozoa along the coast of Onagawa Bay and its vicinity, the northern part of Honshu, Japan. Science Reports of the Tohoku Imperial University, Ser. 4 (Biology) 3: 433-445. Ostrovsky, A. N. (2013). Evolution of Sexual Reproduction in Marine Invertebrates – Example of gymnolaemate bryozoans. Dordrectht: Springer Netherlands. Doi: 10.1007/978-94-007-7146-8 Rouse, S. (2011). Aetea anguina. Bryozoa of the British Isles. Retrieved from http://britishbryozoans.myspecies.info/content/aetea-anguina-linnaeus-1758 Ruppert, E.E., Fox, R.S., and Barnes, R.D. (2004). Invertebrate Zoology: A functional evolutionary approach. Ann Arbor, MN: Thomson Brooks/Cole. Seo, J. E., & Min, B. S. (2009). A Faunistic Study on Cheilostomatous Bryozoans from the Shoreline of South Korea, with Two New Species. Korean J. Syst. Zool., 25(1), 19-40 Temkin, M. H. (1991). Fertilization in the Gymnolaemate Bryozoa (Doctoral dissertation). Retrieved from ProQuest Dissertations and Theses database. (DP23819). Tilbrook KJ (2012) Cheilostomata: first records of two invasive species in Australia and the northerly range extension for a third. Check List 8: 181-183. http://www.checklist.org.br/getpdf?NGD192-11 Wass, R. E., & Yoo, J. J. (1975). 21. – Bryozoa from Site 282 West of Tasmania. Retrieved from Deep Sea Drilling website: http://www.deepseadrilling.org/29/volume/dsdp29_21.pdf Wass, R. E., & Yoo, J. J. (1983). Cheilostome Bryozoa from the southern Australian continental shelf. Aust. J. Mar. Freshw. Res., 34(2), 303-354 Winston JE (1977). Distribution and ecology of estuarine ectoprocts: A critical review. Chesapeake Science, 18: 34‐57. doi:10.2307/1350363. https://fau.digital.flvc.org/islandora/object/fau%3A6214/datastream/OBJ/view/Distribution_and_ecology_of_estuarine_ectoprocts__A_critical_review.pdf Woollacott, R. M., & Zimmer, R. L. (Eds.). (1977). Biology of Bryozoans. New York, NY: Academic Press


Limited information; expert opinion based on observational information or circumstantial evidence