The pretty green rope

  FHL Marine Botany  ::::::::::::::::::::::::::::::   Taxonomy | Habitat | Morphology | Life History | Ecology | Epizoic Growth


Life History


Characteristic tangled mass of the gametophyte form of Acrosiphonia


Large clump of Acrosiphonia growing on the edge of a tidepool




Acrosiphonia has two unique morphology life stages, making it heteromorphic. The gametophyte is a macroalga that is identifiable due to filamentous morphology and hooked branchlets.(2).


The sporophyte, the target of recent research, is a microalga that colonizes Mazaella splendens and Petrocelis. Previously, these sporophyte growth forms were considered to be unique unicellular species, where Chlorochytrium inclusum was the unicell found on Mazaella and Codiolum petrocelidis on Petrocelis. Both of these sporophyte forms are endophytic and are able to survive the hot summer temperatures that are lethal to the gametophyte form (1). Further research has shown that there are other host species including Mazaella heterocarpa, Mazaella sanguinea, Ralfsia pacifica, and Hildenbrandia occidentalis (3). Endophytes release zoospores in late winter, when there is a decrease in host abundance (2).

The recognition of the two microalgae as sporophytes of Acrosiphonia was determined using ITS1 and ITS2 ribosomal DNA sequencing (1).

Reproductive effort of the gametophyte for Acrosiphonia coalita is highest in March and continues until April.





Website created by:

Travis Seaborn

ZooBot Spring Quarter 2009

Friday Harbor Laboratories

University of Washington

All images created by the author, except where indicated, and cannot be used without permission from the author.


1) Sussmann, A. V., B. K. Mable, R. E. DeWreede, and M. L. Berbee. 1999. Identification of green algal endophytes as the alternate phase of Acrosiphonia (Codiolales, Chlorophyta) using ITS1 and ITS2 ribosomal DNA sequence data. Journal of Phycology 35:607-614.

2)Sussmann, A. V. and R. E. DeWreede. 2001. Life history of Acrosiphonia (Codiolales, Chlorophyta) in southwestern British Columbia, Canada. American Journal of Botany 88:1535-1544.

3)Sussmann, A. V. and R. E. DeWreede. 2002. Host specificity of the endophytic sporophyte phase of Acrosiphonia (Codiolales, Chlorophyta) in southern British Columbia, Canada. Phycologia 41:169-177.