Scientists used to think that only mammals and birds experienced different sleep states. More recent research, however, has revealed some reptiles and cuttlefish -- another cephalopod and relative of the octopus -- show non-REM and REM-like sleep.
A new study has found that the octopus has ‘quiet’ and ‘active sleep’, with different episode duration and periodicity, and experiences active sleep after a long episode of quiet sleep.
A number of new products are normally launched at the start of April, and this year did not disappoint.
We asked our contributors what their favorite underwater photography technique was and they sent us images and insights into a range of intriguing techniques from close-up wide-angle to use of reflective cylinders and Snell's window to circular fisheye and snoots to using sunballs and sunrays for backlighting as well as how to create black backgrounds.
In part one of this series, which appeared in issue #103, I suggested a few commandments to consider in order to ensure, as far as possible, that your technical dives are safe and successful. These were: First commandment: Prepare paperwork; Second commandment: Nominate a supervisor; Third commandment: Deploy safety divers. In this sequel, I deliver a few more tablets of stone.
