“Caulerpa taxifolia is a light green macroalga with upright leaf-like fronds arising from creeping stolons. The fronds are flattened laterally and the small side branchlets are constricted at the base (where they attach to the midrib of each frond), are opposite in their attachment to the midrib (as opposed to alternating) and curve upwards and narrow towards the tip. The invasive aquarium clone is morphologically identical to native populations of the species. Frond diameter is 6-8mm and frond length is usually 3-15cm in the shallows, 40-60cm in deeper situations but can grow up to 2.8m in height.”

(NIMPIS 2011, Caulerpa taxifolia general information, National Introduced Marine Pest Information System, viewed 29 January 2011 <http://www.marinepests.gov.au/nimpis>.)

See also: California Sea Grant - Caulerpa species identification key - "feather"