This week, Stu tells us about new research making animals invisible, or rather their tissue transparent, using a common food dye; and Cat tells us about how humpback whales make and use nets of bubbles as tools for hunting, and recently discovered secrets of their mating and birth.Zihao Ou et al. Achieving optical transparency in live animals with absorbing molecules. Science 385, eadm6869(2024). DOI:10.1126/science.adm6869Andrew Szabo et al. 2024. Solitary humpback whales manufacture bubble-nets as tools to increase prey intake. R. Soc. Open Sci.11240328http://doi.org/10.1098/rsos.240328Stephanie Stack et al. 2024. An observation of sexual behavior between two male humpback whales.  Marine Mammal Science https://doi.org/10.1111/mms.13119Watch a video of the humpback whale heat run and birth: https://www.youtube.com/watch?v=BQPAgFH96mQ