Botryllus schlosseri

Botryllus schlosseri
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Tunicata
Class:	Ascidiacea
Order:	Pleurogona
Family:	Botryllidae
Genus:	Botryllus
Species:	B. schlosseri
Binomial name
Botryllus schlosseri (Pallas, 1766)
Synonyms
Alcyonium borlasii Turton, 1807 Alcyonium schlosseri Pallas, 1766 Aplidium verrucosum Dalyell, 1839 Botryllus aurolineatus Giard, 1872 Botryllus badium Alder & Hancock, 1912 Botryllus badius Alder & Hancock, 1912 Botryllus bivittatus Milne-Edwards, 1841 Botryllus calendula Giard, 1872 Botryllus calyculatus Alder & Hancock, 1907 Botryllus castaneus Alder & Hancock, 1848 Botryllus gemmeus Savigny, 1816 Botryllus gouldii Verrill, 1871 Botryllus marionis Giard, 1872 Botryllus miniatus Alder & Hancock, 1912 Botryllus minutus Savigny, 1816 Botryllus morio Giard, 1872 Botryllus polycyclus Savigny, 1816 Botryllus pruinosus Giard, 1872 Botryllus rubens Alder & Hancock, 1848 Botryllus rubigo Giard, 1872 Botryllus smaragdus Milne-Edwards, 1841 Botryllus stellatus Gaertner, 1774 Botryllus violaceus Milne-Edwards, 1841 Botryllus violatinctus Hartmeyer, 1909 Botryllus virescens Alder & Hancock, 1848 Polycyclus renieri Salfi, 1931

Botryllus schlosseri, commonly known as the star ascidian or golden star tunicate, is an invasive, colonial ascidian tunicate that grows on slow-moving, submerged objects, plants, and animals in nearshore saltwater environments.

Individual zooids may grow to 3 millimetres (0.12 in) in size, with colonies reaching 50 millimetres (2.0 in) long .

Tunicate colonies of Didemnum (left) and Botryllus schlosseri (right) overgrowing individuals of the tunicate Styela clava

Its range has spread over the last 100 years to a nearly worldwide extent. Ranging in the western Atlantic Ocean from the Bay of Fundy to North Carolina, this is "the most common colonial tunicate in North America."

This species can be distinguished from Botrylloides sp. by the pattern of zooid growth. B. schlosseri zooids emanate from a center in the manner of the arms of a star. Also, there usually are fewer zooids per cluster (5–8 in B. schlosseri and 10 or more in Botrylloides). There are many colors in which this species can be found, ranging from orange, blue and grey. A colony can be easily be separated from the main body to form an independent colony usually referred to as a subclone. Two colonies may also fuse together if they share common alleles for historecognition.

When sexually productive, these Botryllus are known to produce,"yellowish-white or pale orange tadpole larva" exhibiting an oval outline.

In a study conducted by Heather Boyd, from Stanford University, it was concluded by comparing morphological and genetic experiments that "Botryllus from the Monterey and from Woods Hole, Massachusetts, may be designated contingently as Botryllus schlosseri."