BIOTIC

BIOTIC Species Information for Nematostella vectensis

Researched by

Charlotte Marshall & Angus Jackson

Data supplied by

MarLIN

Refereed by

Dr Simon Davy & Dr Martin Sheader

Taxonomy

Scientific name

Nematostella vectensis

Common name

Starlet sea anemone

MCS Code

D761

Recent Synonyms

None

Phylum

Cnidaria

Subphylum

Superclass

Anthozoa

Class

Hexacorallia

Subclass

Order

Actiniaria

Suborder

Nynantheae

Family

Edwardsiidae

Genus

Nematostella

Species

vectensis

Subspecies

Additional Information

No text entered

Taxonomy References

Manuel, 1988, Howson & Picton, 1997, Stephenson, 1935, Carlgren, 1949, Sheader et al., 1997,

General Biology

Growth form

Cylindrical
Radial

Feeding method

Passive suspension feeder
Predator

Mobility/Movement

Burrower
Temporary attachment

Environmental position

Epifaunal
Infaunal

Typical food types

Hydrobia, Chironomid and Littorina juveniles.

Habit

Attached

Bioturbator

Not relevant

Flexibility

High (>45 degrees)

Fragility

Fragile

Size

Small(1-2cm)

Height

Up to 15 mm

Growth Rate

Insufficient information

Adult dispersal potential

No information found

Dependency

Independent

Sociability

Solitary

Toxic/Poisonous?

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.

Abundance
Abundance generally varies with geographic area and time of year. In Pennington Lagoon, Hampshire, a peak in abundance of up to 2700 individuals / m² is seen from September to October whilst in the Fleet, Dorset, the population peaks at around 1500 individuals / m², in November and December (Sheader et al., 1997). In September 1974, more than 12500 / m² were found in a Norfolk pool and an estimate of over 5 million individuals in a single pool has even been made (William, unpubl., cited in Williams, R.B., 1983). On the south coast of England, individual population numbers tend to peak in late summer, the considerable increase probably being the result of asexual reproduction (Sheader et al., 1997).

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.).

Salinity
In English populations of Nematostella vectensis, the salinity in the vast majority of sites ranges between 2-42 ppt with the greatest abundance in ponds with seasonally varying salinity between 16-32 ppt. (Sheader et al., 1997).

Distribution in Britain and Ireland
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.

Substratum preferences

Mud
Algae

Physiographic preferences

Isolated saline water (Lagoon)

Biological zone

Lagoonal

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,

Reproduction/Life History

Reproductive type

Fission
Budding
Gonochoristic

Developmental mechanism

See additional information
Schizotomous

Reproductive Season

Insufficient information

Reproductive Location

As adult

Reproductive frequency

Annual episodic

Regeneration potential

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

Larvae/Juveniles
Larval/Juvenile dispersal potential	Insufficient information	Larval settlement period	Insufficient information
Duration of larval stage	2-10 days

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 reproduction

Transverse 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 reproduction

In 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,