Microporella borealis


Scientific Name: Microporella borealis

Phylum: Bryozoa

Class: Gymnolaemata

Order: Cheilostomatida

Family: Microporellidae

Genus: Microporella


borealis [Describe here as A. iricolor]

Native Distribution

Origin Realm:

Temperate Northern Pacific

Native Region:

Origin Location:

Temperate Northern Pacific [Japan] Akkeshi, Hokkaido (Kaselowsky et al 2005; Suwa and Mawatari 1998) STATUS STATED [Japan] Approximately 1km offshore of Satsukari fhishing port, Kikonai, Hokkaido (Type locality). (Suwa & Mawatari 1998) TYPE LOCALITY [Korea] Ocheon; Yellow Sea (Seo and Min 2009) STATUS NOT STATED [Japan] Usu, Uchiura (Hunka) Bay, Hokkaido. (Suwa & Mawatari 1998) STATUS NOT STATED [Japan] Usujiri, Kayabe-Gun, Hokkaido. (Suwa & Mawatari 1998) STATUS NOT STATED [Japan] Oshoro Bay. Hokkaido. (Suwa & Mawatari 1998) STATUS NOT STATED [Korea] Geomeunyeo Island, Ocheon. (Seo & Min 2009) STATUS NOT STATED

Geographic Range:

[Western Pacific] Japan and Korea; Yellow Sea (Seo and Min 2009; Kaselowsky et al 2005; Suwa and Mawatari 1998) [Japan] Approximately 1km offshore of Satsukari fhishing port, Kikonai, Hokkaido (Type locality): 42°30.8'N, 140°46.9'E. (Suwa & Mawatari 1998) [Japan] Usu, Uchiura (Hunka) Bay, Hokkaido: 41°41.2'N, 140°27.3'E. (Suwa & Mawatari 1998) [Japan] Usujiri, Kayabe-Gun, Hokkaido: 41°56.7'N, 140°56.5'E. (Suwa & Mawatari 1998) [Japan] Oshoro Bay. Hokkaido: 43°12.8'N, 140°51.4E. (Suwa & Mawatari 1998)

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:


Second Vector:


Vector Details:


Spread Rate:


Date First Observed in Japan:

New species, collected in September 1993 in Hokkaido (Suwa and Mawatari 1998)

Date First Observed on West coast North America:



Impact in Japan:


Global Impact:



Native Temperature Regime:

Cool temperate, Mild temperate

Native Temperature Range:

Cool-temperate temperature; 0.5 to 19˚C (Kaselowsky et al 2005) Muroran in Uchiura (Hunka) Bay near the locality of M. b.: max 18.0ºC in summer and min 2.0ºC in winter. (Clark et al. 2003) Mild 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:

Muroran in Uchiura (Hunka) Bay near the locality of M. b.: max 32.0psu in dry period and min 23.0psu in wet period. (Clark et al. 2003)

Non-native Salinity Regime:

Not applicable

Temperature Regime Survival:

See details

Temperature Range Survival:

RELATED: [Microporella spp.] -1.596 - 26.626 ºC (OBIS 2016)

Temperature Regime Reproduction:


Temperature Range Reproduction:


Salinity Regime Survival:

See details

Salinity Range Survival:

RELATED: [Microporella spp.] 31.235 - 38.201 PPS (OBIS 2016)

Salintiy Regime Reproduction:

Polyhaline, Euhaline

Salinity Range Reproduction:


Depth Regime:

Shallow subtidal

Depth Range:

Material from 5m in depth (Seo and Min 2009) Sample depth 22m (OBIS 2015) 3-6m depth (Kaselowsky et al 2005) 15-27m deep (Suwa and Mawatari 1998) [Japan] Approximately 1km offshore of Satsukari fhishing port, Kikonai, Hokkaido (Type locality): 15m deep. (Suwa & Mawatari 1998) [Japan] Usu, Uchiura (Hunka) Bay, Hokkaido: 27m deep. (Suwa & Mawatari 1998) [Japan] Usujiri, Kayabe-Gun, Hokkaido: 20-25m deep. (Suwa & Mawatari 1998) [Japan] Oshoro Bay. Hokkaido: 15m deep. (Suwa & Mawatari 1998) [Korea] Geomeunyeo Island, Ocheon: 5m deep. (Seo & Min 2009)

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:

Brooding zooids (Suwa and Mawatari 1998) RELATED: [Order: Cheilostomata] Free spawning species produce the characteristic triangular cyphonautes larva. These larvae are long-lived and planktotrophic. The larval body is enclosed in a membranous shell; the size can be up to little over 1 mm. Cyphonautes larvae are not keyed out - if possible at all. (van Couwelaar 2003) [Gymnolaemates] Internal fertilization, whether intracoelomic or intraovarian, is obligatory (Temkin 1994 and 1996, cited in Ostrovsky 2013) [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] 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) [Bryozoa] Members of the phylum Bryozoa are hermaphroditic. Both fertilization and egg brooding may either be internal or external (Ruppert et al. 2004) [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:

RELATED: [Bryozoa] The abundance and taxonomic diversity of benthic bryozoan faunas are directly related to substratum. (Hayward & Ryland 1999) [Bryozoa] Bryozoan colonies are sessile (Hayami 1975) [Bryozoa] Bryozoans are a phylum of sessile, colonial suspension feeders found throughout the world in both marine and freshwater environments. (Tilbrook 2012)

Maturity Size:

Zooecium 0.25-0.34mm wide; 0.39-0.52mm long (Seo and Min 2009) Mature colony of 2.5cm x 2.5cm (Suwa and Mawatari 1998)

Maturity Age:


Reproduction Lifespan:

Matured colonies were obtained between April and June. (Suwa & Mawatari 1998)



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:

Matured colonies were obtained between April and June. (Suwa & Mawatari 1998)



Egg Size:

RELATED: [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:




Oyster reef, Macroalgal beds, Fouling, Other

Habitat Type:

Epiphytic, Epizoic




Semi-exposed, Protected

Habitat Expansion:


Habitat Details:

Found on oyster and scallop shells (Seo and Min 2009; Kaselowsky et al 2005) Offshore (Suwa and Mawatari 1998) Shell of hermit crab; On leaf of Neoholmesia japonica (Suwa and Mawatari 1998) M. b. occurs on the shells of a hermit crab Pagurus sp. In Oshoro Bay and occasionally on the laminae of the red alga Neoholmesia japonica in Usujiri, but most frequently on the shells of cultured Patinopecten yessoensis in Satukari and Usu. (Suwa & Mawatari 1998) M. b. was collected from oyster shell in Korea. (Seo & Min 2009) Semi-exposed, Protected, Fouling (M. Otani, pers. comm.)

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:

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 1999) [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


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: 17-Mar-2016. Hayami T (1975) Neogene Bryozoa from northern Japan. Science Reports of the Tohoku University, Ser. 2 (Geology) 45: 83-126. http://ci.nii.ac.jp/els/110004646784.pdf?id=ART0007368357&type=pdf&lang=jp&host=cinii&order_no=&ppv_type=0&lang_sw=&no=1458033798&cp 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 Kaselowsky, J., Scholz, J., Mawatari, S. F., Probert, P. K., Gerdes, G., Kadagies, N., & Hillmer, G. (2005). Bryozoans and microbial communities of cool-temperate to subtropical latitudes—paleoecological implications. Facies, 50(3), 349-361. Doi: 10.1007/s10347-004-0034-5 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 OBIS. Ocean Biogeographic Information System. http://iobis.org/mapper Access date: 15-09-2016 *Note: genus level data 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. Animal Systematics, Evolution and Diversity, 25(1), 19-40 Suwa, T., & Mawatari, S. F. (1998). Revision of seven species of Microporella (Bryozoa, Cheilostomatida) from Hokkaido, Japan, using new taxonomic characters. Journal of Natural History, 32(6), 895-922. Doi: 10.1080/00222939800770461 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 Van Couwelaar, M. (2003). Zooplankton and Micronekton of the North Sea. Retrieved from http://species-identification.org/species.php?species_group=zmns&menuentry=groepen&id=102&tab=refs 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


Little or no information; expert opinion based on general knowledge