Exclusive: When Tessa Montague learned about #CRISPR, the gene-editing system that was supposed to make it easy to modify any organism, she set her sights on the cuttlefish. The Columbia University neuroscientist dreamed of injecting its embryos with genes that would prompt its neurons to fluoresce as they fired.

The flashes would let her track how this tentacled creature's brain controls one of its most striking behaviors: camouflaging itself by copying patterns it perceives in its surroundings onto its skin. Unlike most animals, she says, “cuttlefish can actually tell us what they see.”

Six years and thousands of embryos later, she has reached a milestone: seven cuttlefish that glow red under fluorescent light. Every cell in their boneless bodies contains a gene encoding a synthetic fluorescent protein—even their eggs and sperm, which means their cuttlebabies glow, too.

The work, posted as a preprint, marks the first time anyone has successfully added a new gene to a cephalopod. https://scim.ag/4ytddWd @NewsfromScience