DIVE LOG AUSTRALASIA ISSUE 413 AUGUST 25

Many Spotted Sweetlips, Plectrorhincus chaetodonoides , have spots all over except for the belly. Often known as Harlequin Sweetlips for the bright juvenile colours.

Most species undergo spectacular colour changes on maturing. The juveniles are very different, even unrecognizable as the same species. Sweetlips feed mainly at night on benthic rubble and sand for invertebrates. During the day. they shelter in caves and shipwrecks or in groups facing into currents They are pelagic spawners, releasing lots of eggs

and sperm into the currents. Like all open water fertilized eggs, the major predator includes sponges, tunicates and possible even Manta Rays. That is, any filter feeder. Juveniles are secretive and often strongly spotted or with stripes or bands. The larvae are pelagic and swim onto reefs and settle when they reach ~10mm. Somehow, these tiny fish can ‘hear’ or ‘smell’ reefs and swim toward these sanctuaries. It is a vital part of their survival and probably a powerful selection agent within the environment Only the fittest will survive! They are secretive and have unique colour patterns. Juveniles swim in a vigorous wavy pattern that gets more exaggerated as the threat increases; i.e. when you get closer. Some suggest that they mimic a flatworm. Adults have a large head, small scales and strong fin spines. Their mouth is relatively small with very thick lips to protect them whilst feeding on the rubble or sand.

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Dive Log Australasia #413 AUGUST’25

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