Reef Report for Thursday, January 11, 2001
Cuttlefish Courtship Observed on the Reef
The wind has continued to stir things up this week, causing visibility to drop at most reef sites. The good news is that Kalinda passengers had a great time despite current conditions. Only 15 knots of wind ruffled their hair and an underwater visibility of eight metres allowed them to spy several of Mother Nature’s creatures of the sea.
Skipper Russel reported that moray eels were particularly active, as were resident cuttlefish families.
Cuttlefish activity has also been high on Ribbon Reef. Cuttlefish are in their mating season and are very busy courting each other. They are so focused on chasing each other, that they’re ignoring the divers and allowing them to get very close to observe. Our knowledgeable friends on the Nimrod Explorer explained to us that cuttlefish are the chameleons of the reef. They can change color in an instant, from flashing pulses of dark grey to red bands through their bodies. This is thought to communicate information to other cuttlefish. It also allows them to blend superbly with their background.
The courtship is fascinating to watch. The male will try to attract a female by flashing a series of dark brown bands down its body. The female will respond with a series of color changes of her own, sometimes going from dark grey to pure white, then instantly going dark again. If all the signals are right, then the two will tentatively touch tentacles for an instant before flashing their color signals again. The ritual may go on for quite some time before mating actually takes place.
The male will insert a sperm package into the females siphon (the cuttlefish equivalent of the nose) and the female uses the package to fertilize her eggs. Once the eggs are fertilized, she very carefully places them in a protected area in the coral. This is the extent of her motherly care for after they are laid she leaves the nest and goes off to die.
One lucky diver, Rick from Michigan in the USA, found a Cuttlefish at Harrier Reef. After taking a few photographs, Rick left the area but found the Cuttlefish was following him. It appeared that the Cuttlefish was more fascinated with Rick than Rick had been with it! The fish even allowed Rick to stroke it on the belly. Rick ended up getting far better photographs than he had ever hoped for.
Divers didn’t see any cuttlefish off Passions of Paradise, although their mooring blocks are attracting an increasing number of lionfish--an interesting species, but more about them next week. Happy diving!
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.
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