405_April_24

MARINE BIOLOGY WITH MIKE SCOTLAND - FISH IDENTIFICATION

Leatherjackets can display strong sexual dimorphism. This is when male and female are distinctly different. Some Lj’s such as the Dusky Lj are identical but many such as the Toothbrush Leatherjacket are very different. Juvenile Triggerfish are often much more brightly coloured than the adults. Once, they mature, male and female look the same. Triggerfish have hard plate like scales covering their bodies. These hard scales get bigger as you get closer to the tail. You can see large spiny scales just in front of the tail in most species. When you see sea shells smashed up, they could well have been eaten by a hungry Trigger fish. The only Cowrie you see out in the open in the Tropics is the beautiful Tiger Cowrie. It has a really strong, thick shell capable of withstanding attacks from the massive jaws of Titan Triggerfish. The Picasso or Hawaiian Triggerfish, Rhinecanthus acueleatus is one of the most colourful. They live in very shallow water in the intertidal zone. You see them when snorkelling over coral sand and rubble beaches. They are very territorial and get annoyed when you get near them. They do not like being photographed and do their best to avoid having their picture taken. This photo was taken at Manta Ray Resort in the Yasawas in North West Fiji. in 2009 I felt that it was close to attacking me when I tried to photograph it. The resort owner had built what was so far the best tropical garden I have seen anywhere in the South Pacific. It is the perfect ‘snorkel heaven’ of your diving dreams. The dive boat has been bringing live broken coral back from dives and ‘planting’ it in front of the resort for ten years. The result is a magic reef with maximum depth of six metres. I managed a two hour dive here on a tiny ten litre Catalina Aluminium tank. The dive Instructor actually came out looking for me as they were not used to serious underwater photographers getting so much fun out of their little reef. I sincerely hope this octopus garden has been maintained. www.divelog.net.au Juvenile Clown Triggerfsh from Thailand

Above: Triggerfish and Remora hunting together at night at Great Detached Reef. Below: Yellowspotted Triggerfish, Pseudobalistes fuscus

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DIVE LOG Australasia #405 - April ‘24