Styela clava - Asian sea squirt

Latin name: Styela clava
Family: Styelidae
Maximum size: Can be up to 20 cm long, but are usually not longer than 8- 12 cm
Life span: 2-3 years, becomes fertile at 10 months
Distribution: Native range is Asia, introduced to Europe, USA, Canada, New Zealand and Australia.
Dispersal capacity: Low, larvae are planktonic for no more than 24 hours before settling to the bottom close to the adults. The world-wide dispersal is considered to be due to human aided transport.
Habitat: Low littoral zone to approximately 40 meters depth. Thrive mainly in wave sheltered areas. The species tolerates salinities between 20 and 32 psu and at temperatures between 2 and 23 °C.
Spawning time: In all seasons, but requires temperatures higher than 15 °C to be able to reproduce.
Diet: Zooplankton, phytoplankton, small larvae and organic particles.
Characteristic features: Two siphons close together at the top of the animal, with four purple or brown longitudinal stripes, alternating with paler stripes. Adult specimens have a conspicuous stalk. The colours may vary from yellow-brown, brown-white, red-brown to yellow-greyish. The upper part of the animal is typically covered with many rounded bumps and swellings. Towards the base of the animal these are replaced with creases running lengthwise along the stalk. The species is easy to separate from native ascidians based on these characteristics.