Fossilised Halimeda

Halimeda is a genus of green macroalgae. The algal body (thallus) is composed of calcified green segments. Calcium carbonate is deposited in its tissues, making it inedible to most herbivores.

As in other members of the order Bryopsidales, individual organisms are made up of single multi-nucleate cells. Whole meadows may consist of a single individual alga connected by fine threads running through the substrate.^[2]

Halimeda is responsible for distinctive circular deposits in various parts of the Great Barrier Reef on the north-east coast of Queensland, Australia. Halimeda beds form in the western or lee side of outer shield reefs where flow of nutient-rich water from the open sea allows them to flourish, and are the most extensive, actively accumulating Halimeda beds in the world.

The genus is one of the best studied examples of cryptic species pairs due to morphological convergence within the marine macroalgae. ^{[3] [4] [5]}

Erect and sprawling Halimeda plants

Species[edit]

Halimeda fossils. The voids are where the Halimeda was, when it was covered with sand, then subsequently rotted, leaving a hole.

Halimeda copiosa at 10 meters depth in shallow cave

References[edit]

1. ^ Guiry, M.D. & Guiry, G.M. (2007). "Genus: Halimeda taxonomy browser". AlgaeBase version 4.2 World-wide electronic publication, National University of Ireland, Galway. Retrieved 2007-09-24. 
2. ^ The Cell Biology of the Bryopsidales
3. ^ Kooistra W.H.C.F., Coppejans E.G.G. & Payri C. (2002). Molecular systematics, historical ecology, and phylogeography of Halimeda. (Bryopsidales) Molecular Phylogenetics and Evolution 24: 121–138
4. ^ Verbruggen H., De Clerck O., Kooistra W.H.C.F. & Coppejans E. (2005). Molecular and morphometric data pinpoint species boundaries in Halimeda section Rhipsalis (Bryopsidales, Chlorophyta). Journal of Phycology 41: 606-621
5. ^ Verbruggen H., De Clerck O., Schils T., Kooistra W.H.C.F. & Coppejans E. (2005). Evolution and phylogeography of Halimeda section Halimeda. Molecular Phylogenetics and Evolution 37: 789-803