The bobtail squid, or the Euprymna scolopes, is a very small, soft squid that does not have many defenses. However, it does have one very impressive trick up its sleeve. It glows at night, because it collects a colony of bacteria called vibrio fishceri, that create the glow that mimics the moonlit sea. The baby squid have to collect their own bacteria in the sea and store them in their bioluminescent organs. The squid, however, need to be able to keep the bad bacteria out, and let the vibrio fishceri in. It is up to their immune system to tell the difference. Here's the thing. It can't! the squid only need to use the bacteria at night, so they burrow themselves in the sand and eject 95 percent of the bacteria from its body every morning, in case it becomes toxic and it releases a bigger population of the bacteria for the baby squid. In doing this, any bad bacteria that may have been stored is released into the ocean, so the squid is not harmed.