I have been working out how much my sea urchins are using up oxygen using closed chamber respirometry jars. The amount of oxygen consumed by the urchins is an indicator of metabolism, and possibly stress.

To measure the oxygen content of the seawater in the jar, I can place a fiber optic cable onto the red spot shown in the video below. Ideally, I don’t want the urchin to be sat on the red spot because they love to eat it! Here’s a video of one of the cheeky urchins sitting on a red spot, and you can see how tilting the jar slightly encourages the urchin to move to the bottom of the jar (and away from the red spot). See… even sea urchins can have a cheeky personality…