Hello and welcome to this instance of our Bioluminescence and Vision Research Cruise Blog. My name is Jorge Perez-Moreno and I’m a PhD Candidate in the CRUSTOMICS Lab, where my research focuses on investigating how organisms adapt to extreme environments, and the molecular basis behind these adaptations. Although the main focus of my work is the study of cave crustaceans, this week I have been fortunate to participate in an amazing project looking at deep-sea crustaceans in the Florida Straits. The main objective of this collaborative research project is to increase our understanding of bioluminescence and how it has driven the visual evolution of organisms in the deep sea.
Bioluminescence and Vision in the Deep Sea
To put it simply, bioluminescence is the ability of an organism to produce light through biological processes. Surprisingly, it is a very common phenomenon that can be observed in a wide variety of environments and species. If you have ever seen fireflies or lightning bugs in the forest, you’ve witnessed bioluminescence in action! Readers from the southern hemisphere might also be familiar with cave glow worms, another bioluminescent creature; or perhaps you have watched one of those amazing documentaries on the deep sea with alien looking jellies and marine creatures that glow in luminous displays of colour. What is the purpose of glowing in the dark you may ask? Well, this depends on the actual organism in question and the environment in which it lives. Regardless, something that is very clear is that this intriguing phenomenon must be extremely important for these creatures as it has evolved independently a multitude of times (some estimate ~50-60 times) in both terrestrial and aquatic environments. Some organisms might use it for predation (think angler fishes and their glowing lures), communication (fireflies flashy signaling), counter-illumination (some fish and shrimp camouflage themselves from predators below by erasing the contrast of the body vs. down-welling light), and even straight-up predator avoidance (by spewing a viscous and luminous substance at your enemies). Another cool fact is that even some animals that cannot innately produce light have evolved solutions to harness the power of bioluminescence, such as squid and fish harbouring bioluminescent microbes in specialised tissues to produce light for them.
The mechanisms of bioluminescence and vision in deep sea environments are intricate and their study requires careful examination from different approaches, therefore we have assembled a team of researchers prepared and excited to tackle all of these questions yet to be answered. During this research cruise, we are targeting two main families of bioluminescent shrimp: the families Oplophoridae and Sergestidae. All of these shrimp make use of autogenic bioluminescence (that is, produced entirely by themselves and not through symbionts) in one way or another. Most of them produce bioluminescent secretions for predator avoidance, and some of them even have specialised organs called photophores where bioluminescent reactions take place and create a semblance of Christmas lights on their bodies. Even though the purpose of these photophores has long been thought to be that of counter-illumination, there are reasons for us to hypothesise that they might also be used for some sort of intraspecific communication. Hopefully we shall be able to find out more about this as part of this research project. Interestingly, some of our previous studies have shown that shrimp that have both methods of bioluminescence also posses more opsin proteins (click here for more info on opsins and vision) than those that only have one, suggesting that their visual abilities might encompass a wider spectrum of light than those shrimp that only spew glowing substances or that simply do not bioluminesce at all. Additionally, throughout our sampling activities during this project we have also come across a variety of other species that are also bioluminescent: fish, salps, krill, sea jellies, and even some super cool amphipods. Even though we are not directly working with these species, we are doing our best to document them photographically (special shout out to Dr. Dante Fenolio) and to make the specimens available to other researchers with expertise in each specific group. Nothing goes to waste during these cruises!
In order to achieve our research objectives, this project has assembled a team of research labs to investigate them from different perspectives. The laboratory of Dr. Tamara Frank (NOVA Southeastern University) will investigate the visual sensitivity of live shrimp by attaching electrodes to their eyes and measuring their reactions to different wavelengths of light. Our lab (CRUSTOMICS at Florida International University) will attempt to correlate these visual sensitivities with the genetics of the shrimp by looking at what genes are active in their eyes and photophores. The Porter lab (University of Hawaii at Manoa) will take this further and investigate exactly in what cells and tissues are expressing those genes that we will previously identify. This way, working in unison in what we are each best at, we will together help unravel the mysteries of bioluminescence and the evolution of vision in the deep sea.