Understanding Marine Behaviours

When chatting with divers about what they are looking for on a dive, some express interest in an easier dive if they are novices, others request dives that are more challenging, or they may ask to visit a specific type of habitat such as a coral reef or shipwreck, yet others express a desire to see larger marine life like stingrays, sharks, manta rays or turtles. It’s easier for the dive centres to fulfil the divers’ requests for the level of challenge and habitat given existing sea conditions, but not as easy to meet demands for marine life as creatures typically move around quite a bit and may not be where they were last sighted. Of course we all participate in diving with the intention to have a good time, so it makes sense to develop an appreciation of the different facets of the marine environment so that we are not disappointed if we fail to sight those marine creatures on our wish list, be they large or small. Learning to spot specific behaviours can add to the enjoyment of a dive when that occurs.

Have you ever noticed that angel fish are typically always in pairs? Another inseparable couple are the banded coral shrimp which are to be found sheltering within the purple vase sponges, have a closer look the next time that you find them, you’ll see that one is larger than the other and that more often than not, it will have pale blue eggs on its underbelly. Shrimp also perform the duty of cleaners, so if you observe larger creatures such as moray eels and groupers with their mouths agape and flared gills while remaining stationary, approach slowly so as not to spook them and see if you can spot shrimp providing dental services, sometimes you’ll even notice them entering and exiting through their gills. Pederson shrimp which make their home within ringed anemones, always bring a smile to my face because when approached, they begin frantically waving their long white feelers to attract you as if to shout, we’re open for business! Neon gobies are also cleaners and often time have queues of blue creole wrasse, parrot fish and others, waiting for service atop the brain corals. The rarest fish that I’ve observed acting as a cleaner is the elusive brotulla, a dusky fish with a ribbon like body and a face that only a mother would like.

Dense aggregations of fish that are usually solitary are an indication of courting or spawning behaviour, other changes in behaviour are also indicators such as when brown chromis (which school mid water) are found densely packed amongst the corals or the obvious spawning activity of yellow wrasse which suddenly dart collectively upwards on some indiscernible cue, to release a cloud of eggs about a metre above the reef before immediately returning to the shelter of the coral.

Sergeant majors are a common fish with oval shaped bodies about 10 cm in length, a yellow back and dark vertical striping, they are also known as footballers. While typically found schooling they can also be found singly with a dark back and displaying territorial behaviour, see if you can spot a purplish, grainy splotch on the coral/rock that it is protecting and you’d have found its egg nest!

Other behaviours that are of interest include small jacks or snappers following a stingray, that’s a sure sign that the stingray is actively hunting prey that is buried in the sand as the jacks/snappers are hoping to score an easy meal when the stingray’s prey attempts to flee. Or how about when trumpet fish curve themselves along a snapper or groupers back for camouflage when migrating to another section of reef. Or the octopus’ penchant for discarding the shells of meals at the entrance of its den, in some instances holding the shells up for camouflage, which to an experienced diver’s eye is a sure sign of the octopus’ presence.

There’s no good reason to fixate on any one facet of diving. By developing a broader appreciation we ensure that every dive is a good dive, it’s just that some are better than others!

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