There’s an old phycological adage saying bull kelp has enough carbon monoxide to kill a chicken. And it’s true. A pneumatocyst — aka a gas bladder — is the bulbous part of many brown algae that allows the seaweed to float. By inflating their bladders full of gas, bull kelp grow straight up underwater and get closer to the sun for photosynthesis. The presence of carbon monoxide in bull kelp was established in 1917. A paper published in the Journal of the American Chemical Society reported a guinea pig, a canary, and a chicken all died in vessels pumped with kelp gas. “Post-mortem examination… showed the characteristic appearances associated with carbon monoxide poisoning.” Those trials were retested in 2020 without harming any animals, and the gas bladder as murder weapon theory held water. “Given that carbon monoxide concentration of 0.01% could kill or render a person unconscious, the largest pneumatocyst analyzed in this study (which held about a wine bottle full of gases), had a CO concentration of 1.6%, resulting in total concentration of 15 times greater than the maximum concentration of carbon monoxide someone with [an average] lung capacity could tolerate before passing out.” So yeah, don’t huff a bull kelp bulb. Maybe a lot of the gas would escape outside of laboratory settings, I don’t know. But if it doesn’t kill you, it still might taste like a sandy fish butt. Macrophycology (SEAWEED) is available to listen at the link in bio or wherever you get your podcasts. Photos via @tiarebuoys (1 & 2), @justinhofman (3), @elakhaalliance (4), @seaforest.ca (5)