BIOTIC Species Information for Nematostella vectensis
|Researched by||Charlotte Marshall & Angus Jackson||Data supplied by||MarLIN|
|Refereed by||Dr Simon Davy & Dr Martin Sheader|
|Scientific name||Nematostella vectensis||Common name||Starlet sea anemone|
|MCS Code||D761||Recent Synonyms||None|
|Additional Information||No text entered|
|Taxonomy References||Manuel, 1988, Howson & Picton, 1997, Stephenson, 1935, Carlgren, 1949, Sheader et al., 1997,|
|Feeding method||Passive suspension feeder
|Typical food types||Hydrobia, Chironomid and Littorina juveniles.||Habit||Attached|
|Bioturbator||Not relevant||Flexibility||High (>45 degrees)|
|Height||Up to 15 mm||Growth Rate||Insufficient information|
|Adult dispersal potential||No information found||Dependency||Independent|
|General Biology Additional Information||Although the column rarely exceeds 15 mm in length, exceptionally large individuals may reach 60 mm long when fully extended. Furthermore, food availability probably limits size in this species.
Only females are found in the south coast populations of England (Sheader et al., 1997) and there seems to be only asexual reproduction in the UK (M. Sheader, pers. comm), therefore male size at maturity is not relevant. See reproduction for further information.
|Biology References||Manuel, 1988, Stephenson, 1935, Sheader et al., 1997, Hand & Uhlinger, 1992, Hand & Uhlinger, 1994, Anonymous, 1999(k), Williams, 1991, Williams, R.B., 1983,|
|Distribution and Habitat|
|Distribution in Britain & Ireland||Found on north coast of Norfolk, the east coast of Suffolk, the Blackwater Estuary and Hamford Water in Essex, the Hampshire coast and on the south coast of Dorset.|
|Global distribution||In North America from Nova Scotia to Georgia on the Atlantic coast, from Florida to Louisiana in the Gulf of Mexico and from California to Washington on the Pacific coast. Also found on the South and East coast of England.|
|Biogeographic range||Not researched||Depth range||<1 m to 2 m max|
|Migratory||Non-migratory / Resident|
|Distribution Additional Information||The populations of this species in Britain may either be:
1) relicts from a larger earlier distribution,
2) have arrived in Britain from North America by natural mean or
3) have been introduced by human agency.
Dispersal between lagoons may be via floating mats of Chaetomorpha sp. thus extending their dispersal potential. Biological zone is not relevant because this species lives in lagoons, generally not exposed to tidal action.
Posey & Hines (1991) suggested that in the Rhode River, America, the distribution outside lagoons may be limited through predation by shrimps.
Nematostella vectensis is often found using Ruppia sp. or Chaetomorpha sp. as substrata (Williams, 1991).Depth
Although the species is usually found in water less than 1 m deep, a few live down to 2 m water depth (M. Sheader, pers. comm.).
Nematostella vectensis is found on north coast of Norfolk, the east coast of Suffolk, the Blackwater Estuary and Hamford Water in Essex (Carol Reid, English Nature, pers. comm.), the Hampshire coast and on the south coast of Dorset. Nematostella vectensis was first described as a new species from brackish pools on the Isle of Wight.
|Physiographic preferences||Isolated saline water (Lagoon)
||Wave exposure||Ultra Sheltered
|Tidal stream strength/Water flow||Very Weak (negligible)
||Salinity||Variable (18-40 psu)
Low (<18 psu)
|Habitat Preferences Additional Information|
|Distribution References||Manuel, 1988, Stephenson, 1935, Sheader et al., 1997, Hand & Uhlinger, 1992, Hand & Uhlinger, 1994, Posey & Hines, 1991,|
|Developmental mechanism||See additional information
|Reproductive Season||Insufficient information||Reproductive Location||As adult|
|Reproductive frequency||Annual episodic||Regeneration potential||No|
|Life span||Insufficient information||Age at reproductive maturity||<1 year|
|Generation time||Not relevant||Fecundity||Up to 2000 eggs|
|Egg/propagule size||170-240 µm in diameter||Fertilization type||Internal|
|Reproduction Preferences Additional Information||Nematostella vectensis is known to reproduce both sexually and asexually. In the UK there seems to be only female asexual reproduction (M. Sheader, pers. comm.). males are absent from populations of Nematostella vectensis on the south coast of England suggesting that these populations produce all their offspring asexually (Sheader et al., 1997). Furthermore, it is likely that all the females are from one clone (M. Sheader, pers. comm.). Studies from American sexually reproducing populations have produced valuable information concerning gametes and larvae and some of this information is provided below. Unless otherwise stated, all the information in the asexual reproduction and sexual reproduction sections below are taken from Hand & Uhlinger (1995) and Hand & Uhlinger (1992) respectively.
Asexual reproductionTransverse fission Asexual reproduction is achieved through transverse fission. Transverse fission is known in only four other sea anemones (Shick, 1991, cited in Hand & Uhlinger, 1994). In the laboratory, most fissions were found to take place at night and only in well expanded individuals. The fragment produced by fission is usually shorter than the oral piece and sometimes multiple fission occurs, producing two or three fragments. From the time of fission to the time of the first successful food capture, some fragments regenerated within three days. Although asexual division becomes common at about 10 weeks, it has been noted as early as seven weeks. Increased food intake leads to an increase in the frequency of fission and starvation can suppress the process (Hand & Uhlinger, 1995).
Budding Anemones with multiple oral-crowns are common in both natural and laboratory reared populations of Nematostella vectensis. Fission by such individuals produces normal single-crowned anemones. This is known as budding and is extremely rare in anemones.
Sexual reproductionIn the laboratory, Nematostella vectensis became sexually mature at 3-4 months old and at column lengths of between 1.5-3.5 cm. Gametes were found to be produced at all times of the year. Fritzenwanker & Technau (2002) found that, in the laboratory, a combination of feeding regime, dark-light cycle and temperature shift synergistically induced gametogenesis in adult polyps from the Rhode River in America. They summarized by saying that the combination of 4 days of feeding in the dark at 18 °C followed by illumination at 24 °C produced the highest number of eggs. The number of eggs is dependent on adult size. Large individuals reared in the laboratory can produce up to 2000 eggs. Eggs are 170-240 µm in diameter and are released embedded in a gelatinous mucoid mass. In the laboratory, spherical ciliated planula larvae emerge from the egg masses between 36-48 hours after fertilization. These larvae are active swimmers from the age of about 3 days old but spend periods of inactivity on the bottom. After a week they settle by which point they are between 250-500 µm long and have four tentacles. By the time they are two months old they are approaching sexual maturity, are 2-5 cm long and have up to 16 tentacles.
|Reproduction References||Stephenson, 1935, Sheader et al., 1997, Hand & Uhlinger, 1992, Fritzenwanker & Technau, 2002, Hand & Uhlinger, 1995,|