Queensland Seaweed – Turbinaria ornatum

This is the Spiny Tops seaweed, Turbinaria ornatum, photographed at Cape Tribulation in Queensland, Australia. Superficially, it looks like the seaweed Sargassum crassifolium featured in a previous Posting. However, if you look closely, you can see that here the ‘fronds’ are much thicker and rounder. They are actually the expanded ends of small branchlets. They look a bit like small cookies that have been cut out of thin dough with a serrated-edge cookie cutter.

A. B. Cribb in his book Seaweeds of Queensland, A naturalist’s guide (ISBN 0-9595607-1-8) says about this species that:

The axis bears closely placed top-shaped branchlets with rigidly spiny margins. Eventually a gas-filled cavity develops in these branchlets and the buoyancy keeps the plant erect when submerged. This species is restricted mainly to the tropics where it is common on coral reefs.

Damon Ramsey in his book Ecosystem Guides, Tropical Seashores of Australia (ISBN 978-0-9757470-6-3) tells us that in these very distinctive seaweeds:

Along the top half of the stalk many smaller branchlets grow off to form a dome shape, and each has flat, star-shaped spikes at the end. They can be common in the murkier sandy shallows, and sometimes wash up on tropical beaches.