BIOTIC

BIOTIC Species Information for Ciona intestinalis

Researched by

Angus Jackson

Data supplied by

MarLIN

Refereed by

Dr John Bishop

Taxonomy

Scientific name

Ciona intestinalis

Common name

A sea squirt

MCS Code

ZD71

Recent Synonyms

None

Phylum

Chordata

Subphylum

Tunicata

Superclass

Class

Ascidiacea

Subclass

Order

Enterogona

Suborder

Family

Phlebobranchiata

Genus

Ciona

Species

intestinalis

Subspecies

Additional Information

Also sometimes known as a sea vase.

Taxonomy References

Svane & Havenhand, 1993, Naranjo et al., 1996, Millar, 1970, Fox, 1994(a),

General Biology

Growth form

Cylindrical

Feeding method

Active suspension feeder

Mobility/Movement

Permanent attachment

Environmental position

Epifaunal

Typical food types

Seston

Habit

Attached

Bioturbator

Not relevant

Flexibility

High (>45 degrees)

Fragility

Fragile

Size

Medium(11-20 cm)

Height

Up to 15 cm

Growth Rate

10-20 mm/month

Adult dispersal potential

None

Dependency

Independent

Sociability

Gregarious

Toxic/Poisonous?

General Biology Additional Information

Although not strictly gregarious, Ciona intestinalis occurs mainly in dense aggregations such that it dominates the substratum. These aggregations are believed to be caused by hydrodynamic conditions rather than some preferential selection mechanism by the larvae (Havenhand & Svane, 1991) but see Adult distribution. In Swedish shallow waters there are two distinct growth phases: in summer/autumn after settling and in spring/early summer before spawning. Growth rates have also been recorded as up to 0.7 percent of body length per day. Growth rate is dependent on temperature and body size. The species is permanently hermaphroditic so the sexes are not separate. Filter feeders including ascidians are known to be able to accumulate trace elements such as heavy metals. A detailed account of the anatomy of Ciona sp. is provided by Millar (1953).

Biology References

Robbins, 1985, Svane & Havenhand, 1993, Schmidt, 1983, Naranjo et al., 1996, Petersen et al., 1995, Millar, 1970, Fox, 1994(a), Millar, 1953,

Distribution and Habitat

Distribution in Britain & Ireland

Widely distributed round British and Irish coasts.

Global distribution

Widely distributed throughout temperate regions of the world.

Biogeographic range

Not researched

Depth range

Lower shore to at least 500 m

Migratory

Non-migratory / Resident

Distribution Additional Information

Growths of the hydroid %Tubularia larynx% may greatly enhance the settlement and may be a causative factor for ascidian blooms (Schmidt, 1983). Ciona intestinalis is believed to have originated as a North Atlantic species but has spread widely through shipping to all temperate regions.

Substratum preferences

Other species (see additional information)
Algae
Artificial (e.g. metal/wood/concrete)
Bedrock
Large to very large boulders
Small boulders

Physiographic preferences

Open coast
Offshore seabed
Strait / sound
Sealoch
Ria / Voe
Estuary
Enclosed coast / Embayment

Biological zone

Upper Infralittoral
Lower Infralittoral
Upper Circalittoral
Lower Circalittoral

Wave exposure

Moderately Exposed
Sheltered
Very Sheltered
Extremely Sheltered
Ultra Sheltered

Tidal stream strength/Water flow

Moderately Strong (1-3 kn)
Weak (<1 kn)
Very Weak (negligible)

Salinity

Full (30-40 psu)
Reduced (18-30 psu)
Variable (18-40 psu)

Habitat Preferences Additional Information

Distribution References

Svane & Havenhand, 1993, Schmidt, 1983, Havenhand & Svane, 1991, Naranjo et al., 1996, Millar, 1970, Fox, 1994(a), Branch et al., 1994,

Reproduction/Life History

Reproductive type

Permanent hermaphrodite

Developmental mechanism

Lecithotrophic
Oviparous

Reproductive Season

All year

Reproductive Location

Water column

Reproductive frequency

Annual protracted

Regeneration potential

Life span

1-2 years

Age at reproductive maturity

<1 year

Generation time

<1 year

Fecundity

2000-3000 eggs per spawn

Egg/propagule size

160 µm diameter

Fertilization type

External

Larvae/Juveniles
Larval/Juvenile dispersal potential	100-1000m	Larval settlement period
Duration of larval stage	2-10 days

Reproduction Preferences Additional Information

Reproductive frequency: The Plymouth Marine Fauna (Marine Biological Association, 1957) recorded Ciona intestinalis reproduction throughout the year. In more northerly populations (Sweden), gamete release peaks in May / June. In Sweden, a variety of reproductive frequencies occur. In shallower waters (0-8m) and reduced salinity (20 psu) the species tends to be semelparous whereas in deeper (15-30m), more stable waters with full salinity (30-32 psu) the species reaches larger sizes, lives longer and is more iteroparous. Adults may reach 2-3 years of age although more typically live for just one year.
Spawning: Reproductive capability is size rather than age dependent. In the laboratory, settlement and spawning can be controlled by manipulation of light levels (Whittington, 1967; Woollacott, 74). Light intensity may have some role in the field but spawning and settlement may occur at any time. Whittington (1967) noted that Ciona intestinalis spawned within 4min (±2.6) of exposure to light. Therefore, light exposure may synchronize spawning in some instances, and Ciona intestinalis has been reported to spawn around dawn (Whittingham, 1967).
The species is not self fertile and fertilization is external. Sperm remain viable for up to 16 hours after release in the absence of egg substances. However, in the presence of egg substances the sperms viability is reduced to 1.5 hours (Bolton & Havenhand, 1996).
After release, the eggs remain viable for fertilisation for up to 30 hours. The eggs are negatively buoyant and sink in still water. They are adhesive and stick to the substratum. The eggs are about 160 microns in diameter, yolky and red or green in colour. Long tapering outer follicle cells radiate from the surface of the eggs. Eggs may be released individually or in mucus strings. The mucus strings tangle with and readily adhere to nearby adults.
Dispersal: The embryonic period of development occurs over around 24 hours but is temperature dependent. The newly hatched 'tadpole' larvae may escape from the mucus strings to disperse in the plankton (40-60% of larvae) or may be retained until settlement. Retention in the mucus string may explain the dense aggregations of adults found. In the laboratory, settlement of the swimming larva may take up to six days but in the field this is usually much less (minutes or hours). Some dispersal is possible at the egg stage but most occurs during the short swimming larval stage and is, therefore, limited.

Reproduction References

Svane & Havenhand, 1993, Naranjo et al., 1996, MBA, 1957, Millar, 1953, Whittingham, 1967, Bolton & Havenhand, 1996, Yamaguchi, 1975,