Belcaid, et al. PNAS https://doi.org/10.1073/pnas.1817322116 (2019)

The bobtail squid, Euprymna scolopes, is a model cephalopod that now joins Octopus biomaculoides in having its genome sequenced. Like its eight-armed relative, the bobtail’s genome is large and quite repetitive—over 50% of elements were repeated. There are also signs that much of the bobtail’s genome has been considerably reorganized since its split from the last common ancestor to other bilaterian animals.

Genetic signatures were particularly distinct in two areas specialized in the squid to house symbionts: the light organ, where bioluminescent Vibrio fischeri reside, and the accessory nidamental gland, a reproductive organ that also harbors a bacteria population. Genes in the former structure are related to immunity and the eye, while the genes in the latter appear unique to the bobtail, suggesting different evolutionary trajectories to foster symbiotic relationships.