Sargassum Identification Guide

Two species of sargassum are found in the Carribean: Sargassum natans and Sargassum fluitans. The photos and drawings below provide assistance in differentiating between the two.

Click on any photo below to open a larger version.


Above: Sargassum natans, left, and Sargassum fluitans, right – photo by GCRL

Above: Sargassum natans, Common Gulfweed – photo by Phillipe Rouja

Above: Sargassum fluitans, Broad-toothed Gulfweed – photo by GCRL

The characteristics described below are useful in differentiating between the two species. However, characteristics vary and identification of a particular sample may not be straightforward.


Sargassum natans

  • Pods – usually tipped with spikes or small leaves
  • Leaves –  long-stalked, narrow


Sargassum fluitans

  • Pods – usually not tipped with spikes or small leaves
  • Leaves – short-stalked, broad

Above – Illustrations by Julia S. Child (Schneider and Searles, 1991)

This identification guide courtesy of Dr. Jim Franks and the University of Southern Mississippi Gulf Coast Research Laboratory – please click HERE for their site.

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