Taxonomy
Nanomia bijuga
Distribution
Status
Conservation status
Ireland: Not considered threatened.
Europe: Not considered threatened.
Global: Not considered threatened.
Legal status
Nanomia bijuga is not afforded legal protection in Ireland.
Native status
Resident
Invasiveness
Not assessed
Species Biology
Identification
Key identification features include:
• Approximately 10-20 cm long when contracted, 50 cm when relaxed
• Tentilla have a single terminal process
• The pneumatophore is ovoid with a red pigmentation cap
• 10-20 pumping ridged bells (nectophores) arranged below for locomotion
• Nectophores have a cube shape
Habitat
Nanomia bijuga is found in oceanic and coastal habitats, and has been recorded from the surface down to a depth of 1850 m.
Source: Kirkpatrick & Pugh, 1984; Mapstone, 2015; Totton, 1965
Life cycle
Nanomia bijuga are dioecious with alternating male and female gonodendra along the stem. The life cycle is entirely planktonic. In the northeast Atlantic, adult colonies appear to reach highest abundance during June-July and small post larval colonies are also present during this time. In the Gulf of Maine and some Norwegian fjords, it has apparently established semi-resident populations surviving through winter.
Source: Haberlin et al., 2016; Mapstone, 2015; Totton, 1965
Threats faced
This species has not been assessed.
Distribution
World distribution(GBIF)
Considered cosmopolitan in distribution, with records from 60°N-59°S.
Source: Mapstone, 2015; Totton, 1965
Irish distribution
Record suggest Nanomia bijuga is primarily found on the western and southern coastlines, sometime in high abundance. Distribution extends into the Celtic Sea and shelf waters and possibly into the Irish Sea.
Source: Haberlin et al., 2016; Kirkpatrick & Pugh, 1984
Temporal change
Records submitted to Data Centre in 2024
The following map is interactive. If you would prefer to view it full screen then click here.
Further information
There are two Nanomia species, Nanomia cara and Nanomia bijuga, and both have probably been confused in many historic sightings. It is likely that many observations recorded as N. cara are in fact N. bijuga.
References
Publications
Haberlin, Damien, et al. "Diversity and occurrence of siphonophores in Irish coastal waters." Biology and Environment: Proceedings of the Royal Irish Academy. Vol. 116. No. 2. Royal Irish Academy, 2016.
Kirkpatrick, P. A., and P. R. Pugh. "Siphonophores and Velellids." Synopsis of the British Fauna (New Series) no. 29 (1984): 154.
Mapstone, Gillian. "Correction: global diversity and review of Siphonophorae (Cnidaria: Hydrozoa)." PloS one 10.2 (2015): e0118381.
Totton, Arthur Knyvett, and Helene E. Bargmann. A Synopsis of the Siphonophora. British Museum (Natural History), 1965.