Species description: This sea squirt forms patches of tightly clustered small individual zooids connected by a bright yellow creeping stolon. Each zooid is approximately 4 mm in length with two small siphons, and is attached to the stolon via a short stalk. The colony has an overall green to yellow colouration, and individual stolons are translucent yellow. Clumps of yellow, angular, star-shaped buds appear from the stolon in the summer and autumn.

Habitat: Found on artificial hard substrata in marinas and harbours, and also beneath stones on low shore in sheltered silty areas. Often grows on other attached organisms like seaweeds or other ascidians.

Distribution: First reported from Northern Ireland in 2015 from Strangford Lough and Carlingford and now spreading. Recorded from several sites around Britain and Ireland and spreading.

Similar Species: Could potentially be confused with the native species Perophora listeri although this lacks the green-yellow tinge and has longer stalks, causing them to flop over when removed from the water whereas Perophora japonica remains upright. The bright yellow star-shaped buds are only found in Perophora japonica.

Key Identification Features:

• Green to yellow colony made up of small zooids attached to a bright yellow stolon.
• Individual translucent yellow zooids attached to stolon via a short stalk.
• Clumps of yellow, star-shaped buds on stolon in summer and autumn.

Distribution Map from NBN: Perophora japonica at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Perophora japonica at iNaturalist World Species Observations database.

WoRMS: Perophora japonica at World Register of Marine Species. Accepted name: Perophora japonica Oka, 1927. AphiaID: 103758.

Classification: Biota; Animalia; Chordata; Tunicata; Ascidiacea; Phlebobranchia; Perophoridae; Perophora