Reef Report for Wednesday, January 31, 2001
YOU SHOULD BE DIVING!!!
The weather is delicious, and if you havenít been wet, or are not planning to be wet this weekend, SHAME ON YOU!!!
This week, visibility on Flynn and Milln reefs has topped 30 metres.
Calm seas and stacks of sunshine have thrilled certified divers and learn to dive students alike.
30 metres visibility was experienced at the Fish Market, where Passions of Paradise was moored. Certified divers saw a Titan Triggerfish munching on a juvenile Crown of Thorns Starfish. The intro divers were lucky enough to see some leafy sea dragons as well as a Common Helmut Gurnard displaying its ordimental pectoral fins.
The Nimrod Explorer also had some exceptional visibility with 30 metres at Pixie Pinnacle. The sea remained glassy calm for most of the trip. Under the calm conditions the nudibranchs were getting it on! On a single dive 5 different species were observed mating. Nudibranchs are classed as Molluscs, and are related to the giant clam and the common garden snail. Unlike their relatives, nudibranchs have taken a different evolutionary path, they have disposed of the shells that the clams and many other molluscs use for protection, and opted to use chemicals to protect themselves. Many species do not manufacture poisons of their own, they "borrow" from other reef organisms.
Nudibranchs will feed on the most toxic sponges and algae they can find. They ingest the poison and somehow store it in their skin, so if a hungry fish should come along and gobble up the Nudibranch, the foul taste would force the fish to spit it out immediately.
Many nudibranchs are brightly coloured to advertise the fact that they are poisonous to eat. It is a warning that works well, as the nudibranch is ignored by most reef predatorss. In fact the only common predator of the nudibranch is...other Nudibranchs!
It is fascinating to watch nudibranchs mating. Each individual is a hermaphrodite, that is both male and female at the same time. They circle each other for a short while, then meet head to head and start "kissing" They then move down each other's body and begin to mate. Each one gets it's eggs fertilized in the process, which takes several minutes.
Wind will be light over the weekend, blowing North East 10 knots. There may be a few scattered showers as well.
The weekly reef report is written by Sue-Anne Chapman of Pro Dive Cairns, who compiles them from the many conversations she has with divers, dive instructors, captains, and others in the Cairns dive community. The report is published weekly in the Cairn Post, the local daily paper and appears here thanks to the courtesy of Pro Dive Cairns.
Index of all reef reports.