The Hawaiian bobtail squid is basically an adorable underwater vampire. It sleeps all day buried in the sand, hunts at night (though not for blood) and, thanks to colonies of glowing bacteria that live inside it, it even kind of sparkles (Team Bobtail > Team Edward).
A new study suggests that the bacteria are more than just a built-in nightlight, though, and may control when the squid wakes and sleeps.
What’s even cooler: these symbiotic bacteria function as a bacterial alarm clock, helping to regulate the squid’s daily circadian rhythms. A “circadian rhythm”, a.k.a. a body clock, is basically a giant cellular war between proteins — some molecules compete to accumulate, while others work furiously to break things down. This complex array of switches and feedback loops is ultimately regulated according light/dark cycles provided courtesy of the sun. It’s the same process that makes us feel tired at night, and jet lagged when we switch time zones. In E. scolopes it regulates its urge to FEED!
A new study by Heath-Heckman et al. (2013) provides convincing evidence that bacterial light production (and metabolic products produced by V. fischeri during this process) are required for the squid to regulate its own body clock. This is crazy but totally cool biology – it’s akin to us humans being required to drink probiotic yogurt in order to sleep. In this hypothetical scenario, our own body wouldn’t know when it should sleep on its own, since sleep would only be cued after our body detected the correct signals from bacterial proteins. [Deep Sea News]