Dictyota bartayresii

Crude extract from Bahamas specimens inhibits the sea urchin A. punctulata (Bolser and Hay 1996). Pachydictyol A from Guam specimens (as Dictyota bartayresii) inhibits the fish Z. flavescens (Wylie and Paul 1988)... 

PI originally attracted attention owing to two unusual habits. It feeds on seaweed, and although many seaweed-eating amphipods have broader tastes, PI nibbles at only one species. It feeds only on a flat-bladed brown seaweed called Dictyota bartayresii. Specialist feeders are less common among marine organisms than on land, but PI seeks out this one species even when other Dictyota seaweeds are more abundant. 

Dictyota species are rich with unpleasant-tasting chemicals to discourage grazing fishes. Amphipods and other small creatures often find safety in among such unpalatable seaweeds, where fishes are infrequent visitors. The chemicals in Dictyota bartayresii are not unpleasant to PI, and in fact the amphipod uses them to identify the seaweed it eats. Conceivably, PI could also sequester these distasteful compounds for its own protection perhaps surprisingly, it does not. 

Pachydictyol A/making a refugee for amphipods diterp. pachydictyol A Dictyota bartayresii in the Caribbean, and oth - Phaec h. Hay 1996... 

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