This squid farms glowing bacteria in its body to erase its own shadow

The Hawaiian bobtail squid hatches with no bacteria at all, then within hours recruits a specific microbe, Vibrio fischeri, into a light organ on its underside. The bacteria glow to match moonlight filtering down from above, cancelling the squid's silhouette so predators hunting from below see nothing. It feeds and shelters its glowing tenants for life.