We went out for a quick snorkel to look for Southern Bobtail Squid at Quiet Corner last night. The weather has been HOT, so it was still over 30 degrees at dusk. The water is about 23 degrees too. It turned out they were quite common. We found ten in all.
How to find Southern Bobtail Squid
The trick seems to be to look for sediment-filled depressions in shallow water just behind where the shallow bedrock begins. They sit and wait like little ambush predators hovering above the sand. When disturbed they bury themselves in the sand, which is where they remain during the day.
They are nocturnal, so you’re best to start looking from about half an hour after sunset. They are also tiny. You’re looking for something no bigger than your little finger nail, often even smaller.
Colour changing, glue and acid cells
What I find remarkable is the sophistication of their body cells that perform such a wide variety of functions. The most obvious one is their use of colour. After birth, they also harvest light-emitting bacteria from the water column, and store these in a special organ. This helps camouflage them from below by matching the faint glow of starlight from above the water.
I was using a red light to find them, which doesn’t disturb them as much. The first flashlight photos show the colour near-normal, which is camouflaged against the sand.
The second photos in the following series shows their colour change. This might be a reaction to disturbance but could also be a consequence of the changed colour context the light revealed.
The body cells also contain two other secrets. They secrete a glue which is used to stick sand grains to their body and it’s strong enough to remain intact when they emerge, as in this photo. Finally, the cells can instantly negate the glue’s effect using an acid. As the squid makes its escape, it can leave behind a squid-shaped blob of sand to confuse predators and leave them with a mouthful of sediment.
All in all, Southern Bobtail Squid at Quiet Corner are one of the cutest residents of the reefs at Ricketts Point and relatively easy to see by taking the time to go slow.
