February 17th 2004
Secrets of spawning squid
This striking image was taken on a recent trip to Lizard Island. These squid (Sepioteuthis lessoniana) are often seen on the Great Barrier Reef but they are difficult to approach underwater and their ability to blend in with their background makes them very difficult to photograph.
At about 9am on October 23rd 2003, over the shallow reef flat at Watson's Bay, Lizard Island, I saw two Sepioteuthis hovering quietly in mid water. I quickly snapped a couple of images, before slowly approaching the pair. Instead of swimming away as they usually do, the squid quietly swam forward and descended toward the bottom, twitching their tentacles and showing a beautiful barred colour pattern on their bodies. They got within 20cm of the bottom and then to my surprise, the female entered a small crevice under a Goniastrea coral head and disappeared! The male stayed outside the coral in a distinct "head-up" position, with a dark flush of colour over his body in an apparent warning display (see image above).
The female reappeared after about 10 seconds, and the pair slowly rose up in the water column and moved back to their original station. I realised that they must be laying eggs, so I got the camera properly set up and waited, hoping they would repeat the sequence. After about 2 minutes they did, and I was able to get good images of the whole process!
I stayed with the pair for about 20minutes, during which time the female made about 5 descents to the spawning site. During one pause, I carefully lifted the coral to reveal the egg mass. Given the number of eggs, it was clear that the pair must have been laying there for some time, possibly that whole morning or even part of the day before. The whole spawning sequence is shown below:
The pair hovering mid waterThe pair descend toward the nest site.The female enters the nestThe male stands guard outside the nest (also see top image)The female emerges and the pair ascend.The egg mass under the coral head.
For the photography enthusiasts, the main image was originally a 2048 x 1536 jpeg taken with an Olympus C5050Z 5 megapixel digital camera in a PT-015 underwater housing. The camera was in aperture mode and the image was shot at 1/125 sec at f7 and ISO 64. No flash was used
Words: Dr Andy Lewis
Copyright on all photos: Dr Andy Lewis
Dr Andy Lewis has a fascinating website where you can read about other marine creatures and naural phenomenon he encounters on his eco-tours. Go to: Reef Eco-Tours Ed.