Journey to the Hydrothermal Vents

Tamara Frank received her Ph.D. degree in Aquatic Biology from University of California, Santa Barbara, working on the visual ecology of deep-sea crustaceans (shrimps and crabs) as well as bioluminescence in marine animals and fireflies. She completed postdoctoral fellowships in neurophysiology at the University of Connecticut Medical School and Hatfield Marine Science Center in Oregon, before returning to the deep-sea world on a postdoctoral fellowship at Harbor Branch Oceanographic Institution in 1992. Discovering that Florida is the only state in the continental U.S. that met her temperature requirements, she has lived in Florida ever since. Much of her research has been on the visual ecology of deep-sea animals, studying adaptations to both downwelling light and bioluminescence. Her work has been funded by the National Science Foundation, NOAA NURP, NOAA NRDA, NOAA CIOERT, and the NOAA Ocean Exploration program. She has been chief scientist on 70 research cruises, and participated on 50 more as a lucky hitchhiker, conducting work in the Gulf of Maine, the Gulf of Mexico, the Indian Ocean and off the coasts of Florida, Hawaii, California, the Bahamas, the Canary Islands, Cuba, Costa Rica, Cabo Verde, and Samoa.  As a professor in the Halmos College of Arts and Sciences at Nova Southeastern University, in addition to her research, she mentors graduate students and teaches human anatomy and physiology to undergraduates, and marine physiology and deep-sea biology to graduates. She is the chief scientist on this cruise, and will be carrying out studies on the vision of vent shrimp using electrophysiological techniques. 

Dr. Heather Bracken-Grissom is a marine evolutionary biologist that studies biodiversity from shallow tropical waters to extreme environments including the deep sea, hydrothermal vents and aquatic caves.  Her current research seeks to understand how organisms have adapted to life in darkness and how they use bioluminescence, the generation of light by an organism, to survive.  For her entire career she has lead Decapod Tree of Life projects to study the origins, evolution and diversification of crabs, lobsters and shrimps. More recently, she has combined genomic methods with advanced technologies, including robotics and autonomous sampling, to investigate ‘invisible DNA’ and improve our understanding of underwater migration and community dynamics.  Dr. Bracken-Grissom has led or participated in over 30 research cruises across the Gulf of Mexico and Pacific, searching for novel life and new sources of bioluminescence.  In June 2019, she was part of the research team that captured the first live video footage of a giant squid in US waters, and as part of this expedition she is exploring some of the deepest hydrothermal vents using the human-occupied submersible Alvin.  Her role in this project is to use genomic techniques to study the visual system of hydrothermal shrimps, identify new crustacean biodiversity, and use environmental DNA to characterize vent communities.   Due to her taxonomic expertise, she has two species named after her, a mesophotic reef hermit crab (Cancelllus heatherae) and deep-sea bioluminescent shrimp (Acanthephyra heatheri).   

Growing up in northern California surrounded by rocky shorelines and tidepools, her love for invertebrates was born. Initially, this passion arose from childhood curiosity but persisted throughout graduate and postdoctoral studies and into her present position as a Professor at Florida International University (FIU) and Assistant Director of the Coastlines and Oceans Division within the Institute of Environment.  She has a B.Sc. in Aquatic Science from the University of California-Santa Barbara and a Ph.D. in Evolutionary Biology from the University of Louisiana at Lafayette. 

Jonluke is currently working towards a Bachelor's degree in Marine Biology and Statistics at The University of Delaware. He also studied abroad for a semester in Denmark and Arctic Norway through a program at DIS focusing on polar biology. He has previously worked on research investigating the interactions of oyster aquaculture with the surrounding ecological systems in the Mid-Atlantic Region. Outside the lab he competes on UD’s Sailing team. This will be his very first research cruise. He will be investigating vent shrimp vision through responses in behavior and activity.

Originally trained in math, dance, and art, Sönke Johnsen has studied optics in biology for the last 36 years, the last 25 of which have been at Duke University. He is particularly interested in vision, signaling, and camouflage in the open ocean, but has also worked on coastal, freshwater, and terrestrial species, animal navigation, nocturnal vision, and human cataracts.  His research combines mathematical modeling with behavioral and morphological studies and in-situ measurements and imagery. His field work primarily involves open-ocean research cruises that use SCUBA and deep-sea manned and robotic submersibles, and other imaging and collecting platforms. In addition to exploring the optical and visual tricks that animals perform, Johnsen is interested in improving communication between theoretical and experimental scientists, biologists and physicists, and scientists and artists. Outreach is a strong focus, and Johnsen’s research has been featured in many traditional media outlets, but also in Radiolab, Finding Nemo, The Magic Treehouse book series, the poetry of John Updike, the humor of Dave Barry, and most recently in Ed Yong’s An Immense World. Professor Johnsen has also written five books; The Optics of Life, Visual Ecology, Color in Nature, Into the Great Wide Ocean, and The Radiant Sea, and is currently completing a sixth on animal camouflage and signals. In his spare time, he is an avid nature photographer and tractor enthusiast.

Ruchao Qian earned his bachelor’s degree in biology from Indiana University—Bloomington and his master’s degree in marine science from Nova Southeastern University, where he worked with Tamara Frank, Ph.D., and studied the visual physiology of marine crustaceans. He is currently a Ph.D. candidate in biology at Florida International University, where his research focuses on the visual ecology and sensory biology of insects. His work combines electrophysiological, neurophysiological, and imaging approaches to investigate how insect visual systems function and adapt to different ecological environments. The training he received from Tamara Frank, Ph.D., in compound eye visual physiology provided a strong foundation for his transition from studying crustaceans to studying insects, and he is excited to return to sea and work with Frank again. This will be his second research cruise, but his first opportunity to conduct research in a hydrothermal vent environment. During the cruise, Qian will assist with the collection and experimental study of hydrothermal vent shrimp, help record their visual responses using electroretinography, and use micro-CT imaging to investigate the structure of their compound eyes. Through this work, he hopes to better understand how vent shrimp are visually adapted to one of the most unusual environments in the deep sea.

Haley Glasmann is a Ph.D. candidate in Kevin Boswell’s, Ph.D., Marine Ecology and Acoustics Lab at Florida International University. She grew up in San Diego and attended UC Santa Barbara, where she earned her B.S. in Aquatic Biology. The culmination of her research experiences across working in Costa Rica with the BIOMA turtle program, spending a summer in Moorea, French Polynesia as an NSF REU student, and interning for the U.S. Navy Marine Mammal Program in San Diego, inspired her to pursue a graduate education in the marine sciences.

Haley utilizes SONAR (Sound Navigation and Ranging) technology or scientific echosounders to study the deep sea. Her research is primarily focused in the Northern Gulf of Mexico where she uses acoustics to investigate the Diel Vertical Migration (DVM), which is the largest daily migration of animals on earth! This movement happens every day across the global ocean, yet is variable across ocean basins. Haley hopes to add to the realm of knowledge for mesopelagic communities to be used in deep pelagic conservation and management efforts.

In addition to her research, Haley has a passion for teaching. She has led the marine biology and oceanography class at FIU and teaches indoor cycling at her campus recreation center. She also manages the social media for her lab @boswelllab and the FIU Marine Biology Program @fiumarinebio. To follow along with Haley’s Ph.D. journey, check out her account: @scubahaleykat.

Bruna Cama’s academic career began at the University of York (U.K.), where she received her Ph.D. working on hybrid speciation and the role of pheromones in species diversification in Heliconius butterflies. This work included long field seasons at the Smithsonian Tropical Research Institute in Panama. It was this experience that turned her into a fieldwork creature. Her first postdoc at the University of Edinburgh focused on the genetic structure of locally adapted traits in a hybrid zone between different color morphs of the African queen butterfly Danaus chrysippus. Her work was enabled by a collaboration with the University of Rwanda Center of Excellence for Biodiversity (CoEB) via 7 months of on-site fieldwork including training of local researchers. Feeling ready to switch things up and having felt an affinity for the sea since childhood, she then began her current postdoc at the UCB Museum of Vertebrate Zoology, on recent adaptation to climate change in deep-sea lanternfish.

The genomics of speciation and adaptation remain a running theme in her research, a toolbox that can be put to use on any organism. Still an invertebrate lover at heart, she will return to pheromones and chemical ecology in her upcoming 2027–2030 Marie Skłodowska-Curie (MSCA-GF) Fellowship, a highly collaborative project that will involve multiple institutions across Africa and South America. This cruise will be her first time working at sea, with the aim to collect deep-sea fish for downstream analyses of gut microbiomes and recent adaptation, and hopefully a few cool specimens for the MVZ Ichthyological collections.  

Originally from Belgium, Daphne Cuvelier graduated as a biologist form the University of Ghent and went to pursue her Ph.D. in the Azores (Portugal). There, she started working on the temporal variation of the deep-sea hydrothermal vent communities mostly based on imagery, which continues to be her main research interest.

After concluding her Ph.D, she did a postdoc at Ifremer in France (2012–2013), working with the deep-sea observatories deployed at the hydrothermal vents in the Atlantic (EMSO-Açores) and the Pacific (ONC Canada), revealing biological and environmental rhythms in community dynamics. Since then, her knowledge on imagery and ecological time-series has been put into practice at the abyssal nodule fields, seamounts and other chemosynthetic environments like whale falls.

Recently, she got an exploratory grant to observe fluorescence in deep-sea organisms and ecosystems. It proved to be a great detection tool for less conspicuous hydrothermal vent organisms and appears to hold a huge potential for (semi-) automated ecological assessments in these amazing ecosystems.

Hopefully, some more exciting fluorescence observations will be done during this cruise, in addition to collecting imagery to study the changes that have occurred over time at the hydrothermal vents visited.

Gwyn Loughman is a graduate student in Tamara Frank’s, Ph.D., Deep-Sea Biology Lab. This is his second year serving as science crew on the NSF hydrothermal vent shrimp cruise, where he volunteers as a lab technician supporting researchers with sample processing and field operations.

Loughman’s master’s research is part of the DEEPEND Restore Consortium, which investigates the long-term impacts of the 2010 Deepwater Horizon oil spill on Gulf of Mexico mesopelagic ecosystems. His thesis focuses on Eucopiidae, examining whether their populations were affected by the spill, whether they undergo vertical migrations, and how their abundance differs between offshore and slope habitats. He is scheduled to defend his thesis this fall. He completed his coursework earlier this year.

After earning his master’s degree, Loughman plans to pursue a Ph.D. focused on deep-sea ecology, with particular interests in crustaceans, deep-sea corals, cephalopods, sharks, and siphonophores.

Outside of graduate research, he works as a field biologist for an environmental consulting firm, where he conducts water quality monitoring, performs manatee observations, collects and manages field data, prepares technical reports, and coordinates with construction teams and project stakeholders. His experience includes crustacean and mosquito identification, GIS, RStudio, QA/QC, technical writing, DNA extraction, PCR, gel electrophoresis, and chromatography.

When he is not working, he can often be found scuba diving, baking, attempting to play the drums, or spending time with his dog. A fun fact about him: as a child, he wanted to be a merman—and in a way, he thinks he came pretty close.

Natalie Donato is a marine biologist and artist, specializing in the sensory biology of marine organisms and scientific illustration. She received her undergraduate degree in biology from Oregon State University and spent as much time at the coast as her classes would allow. For her honors thesis, she created a novel nondestructive method to map the electroreceptor pore distributions of sharks and characterize features of aggregating anemone colonies with 3D photogrammetry (photograph-based 3D models), sparking her interest in studying oddball sensory modalities with technological innovations. She simultaneously kept up with her artistic interests, and most notably, she designed and illustrated the Sharks of Oregon license plate, as well as illustrated and authored the Sharks of Oregon poster and educational materials in collaboration with Oregon Sea Grant.

Diving (quite literally) into the deep end of her first year as a Ph.D. student, she will be assisting with her research group’s (Johnsen Lab’s) goals on this cruise, as well as starting the early stages of her graduate research on the sensory systems of deep-sea animals. 

Kiley Jillisky is a master’s student in Dr. Tamara Frank’s lab at Nova Southeastern University. She is currently studying the visual anatomy of 4 hydrothermal vent species through histology and transmission electron microscopy (TEM). She graduated from Coastal Carolina University with a B.S. in Marine Sciences, minoring in Asian studies with a concentration in Mandarin and Asian Arts. At CCU, she worked on various independent studies, including analyzing the biogeochemistry of tidal creeks adjacent to golf courses, season biodiversity and species density in tidal pools, and volunteered for the CCU Shark Project. At NSU, Kiley volunteered with the Save Our Seas lab and species analysis for the DEEPEND project. She currently serves as the Community Engagement Officer for the national steering committee of the Society for Women in Marine Sciences (SWMS), and as the President of the South Florida SWMS chapter.

Danielle received her Ph.D. in Biology from Temple University, in her hometown of Philadelphia, PA, studying deep-sea coral ecosystems and how they are impacted by anthropogenic disturbances. She is currently a Senior Postdoctoral Research Fellow at Florida International University studying bioluminescence and vision in deep-sea crustaceans, and a proud mom to two young aspiring scientists that constantly keep her on her toes. She has also completed Postdoctoral fellowships at the Smithsonian National Museum of Natural History in Washington D.C., studying the evolution of bioluminescence in anthozoan corals and population genomics of deep-sea hydrothermal vent and cold seep animals. She has participated in over a dozen research expeditions, serving as chief scientist on two, and was lucky enough to sail on the R/V Atlantis previously with the HOV Alvin, diving twice in the deep Gulf of Mexico while leading live coral collections and deep-sea sampling. As a postdoc at FIU, in addition to her research, she mentors graduate students and has taught several sections of the Biological Oceanography at Sea course in addition to guest lecturing in Invertebrate Zoology and Genetics courses. She is the primary postdoc on this project and during this expedition she will be collecting and preserving hydrothermal vent animals for genomic sequencing to study their visual evolution and unique adaptations in these extreme environments. 

Maureen Howard is a Ph.D. student in Biological Sciences at Florida International University, where she works in Dr. Heather Bracken-Grissom's CRUSTOMICS Laboratory investigating extraocular photoreception and visual systems in deep-sea crustaceans. She received the Dean's Distinguished Doctoral Fellowship at FIU and graduated summa cum laude from the University of North Carolina Wilmington with a B.S. in Marine Biology and a minor in Geospatial Technology. Her undergraduate research spanned coral ecology, sea turtle rehabilitation, and evolutionary neuroecology, culminating in an honors thesis on opsin-expressing cells in the eyes and skin of the summer flounder that sparked her interest in marine sensory biology. Her doctoral research combines transcriptomics, immunohistochemistry, confocal microscopy, and comparative morphology to better understand how deep-sea animals perceive light and how sensory systems vary across species. She has presented her ongoing research both nationally and internationally, including at the United Nations One Ocean Science Congress in Nice, France. On this expedition, Maureen will serve as a trawl operator and specimen photographer, assisting with deep-sea collections while documenting biodiversity immediately following recovery from the seafloor. She also developed and will maintain the expedition's interactive ArcGIS StoryMap, providing real-time geographic updates, scientific highlights, and outreach throughout the voyage. Beginning her third year of doctoral study this fall, Maureen plans to complete her qualifying examinations and advance to Ph.D. candidacy while assuming the role of Undergraduate Academic Advisor for all Marine Biology students at Florida International University.

Rebecca received her B.S. in Marine Science with Leadership Distinction in Research from the University of South Carolina, where she first developed an interest in sensory biology during her freshman year. She went on to receive her M.S. in Marine Biosciences from the University of Delaware, with her research examining the environmental, size-dependent, and metabolic influences on vision in fiddler crabs along the US Atlantic coast. She is currently a laboratory technician at the University of Delaware in Dr. Jonathan Cohen’s lab, supporting a variety of projects in animal physiology and behavior, with a primary focus on the sensory physiology and photobehavior of hydrothermal vent shrimp. This will be her third research cruise. In the fall, she will begin her Ph.D. at Dartmouth College as a McCulloch Fellow, where her research will focus on the dietary and visual ecology of muskoxen.

Mary Williams is a Ph.D. candidate in the Department of Biological Sciences at Florida International University, where she conducts research in Dr. Heather Bracken-Grissom's Crustomics Laboratory. Her research integrates molecular ecology, environmental DNA (eDNA), microbial ecology, and biodiversity science to better understand marine ecosystems and develop innovative approaches for monitoring and conserving ocean biodiversity. Although her primary research has focused on coral reef ecosystems throughout the Florida Keys and Caribbean, she is broadly interested in applying molecular tools to study biodiversity across diverse marine environments, from shallow tropical reefs to the deep sea. Mary received her Bachelor of Science in Biology from Old Dominion University where her interest in marine science first developed through various internships from Florida bay sponges to deep sea fishes. As a doctoral researcher, she has combined field ecology and molecular biology to investigate how environmental DNA can reveal marine biodiversity that is often overlooked by traditional survey methods. Her dissertation explores coral reef biodiversity across multiple spatial and temporal scales, including the use of eDNA to examine reef communities, sponge-associated biodiversity, microbial communities, and diel shifts in reef ecosystems. Through this work, she aims to improve molecular approaches for understanding ecosystem health and informing marine conservation. Her research has been supported through grants she has received from Mission Blue, IWFA, CREST, and FIU women’s explorer award. She has presented her work at national and international scientific conferences, including the International Coral Reef Symposium and the One Ocean Science Congress. During this expedition, Mary will help oversee the collection and processing of environmental DNA samples to investigate microbial and biological communities associated with hydrothermal vent systems.

Angel is currently entering his 4^th year as a doctoral candidate in the Crustacean Systematics and Genomics (CRUSTOMICS) Lab at Florida International University. His research focuses on using OMICs methods in tandem with analytical chemistry to both elucidate species within hydrothermal vent environments and analyze the metabolic processes by which chemoautotrophic symbioses occur within host-symbiont microbiomes and environmental microbiomes. Angel completed his A.A. at Indian River State College along with a degree from the Embry-Riddle Aeronautical University Gaetz Aerospace Institute in 2020 focusing on aerospace engineering. Upon completion, he then joined Florida International University (FIU) as a marine biology major, from which he graduated in 2022. Shortly after, he joined the CRUSTOMICS Lab as lab manager, then eventually joined as a doctoral student in the fall of 2023. During this time, Angel has also completed his training as a licensed PADI Divemaster and sidemount diver, looking forward to completing his cave diver training after his tenure at FIU. He has also had the opportunity to sail on three previous scientific expeditions: once along the Florida Keys, once aboard the tall ship, Statsraad Lehmkuhl, during the “One Ocean” expedition, and once during summer 2025 to the Mid-Atlantic Ridge, where he began collections for his thesis. Angel is part of the scientific research team on this cruise and will be conducting his work in environmental DNA analysis and host-symbiont interactions.

Tucker Trawl - Tamara Frank

Animal Collections

In addition to collecting shrimp directly on the vents with the Alvin submersible, we are also going to use a Tucker Trawl to collect animals in the water column at night. The Alvin submersible dives will take place during the day, leaving the night available to deploy a trawl net, and who needs sleep anyway when there are such amazing animals to see. I have worked on the visual systems of a number of deep-sea species, and have discovered that it’s impossible to find out what the animals are seeing if they die when brought from the depths up to the surface. While most people think that it’s the pressure change that kills them, that’s not true for most deep-sea species that live above 1000m (~3300 feet). Only fish with swim bladders can’t handle the pressure change because their swim bladders burst as the air inside expands too quickly when the pressure decreases. Luckily for us, most animals do not have air-filled spaces and therefore do just fine with the pressure changes. What kills them are the much higher surface temperatures. For example, in the tropics and subtropics, many of these deep-sea animals are found in waters where the temperature is between 7 and 10^o (roughly 45 to 50^o F), and bringing them up into surface waters when it can be as hot as 30^o C (85^o F) basically cooks them. In addition, eyes of deep-sea animals are extraordinarily sensitive, and exposing them to surface light irreparably damages their eyes. Think about what would happen to your vision if you stared at the bright Florida sun at noon for five minutes without blinking. Even ship lights are too bright, so in order the collect live animals that are not blind or cooked, special collecting techniques are needed. That is the purpose of the Tucker Trawl. It can be opened and closed at depth, and my net has a specially designed collecting vessel, called a cod-end, at the end that closes when the net closes. The cod-end is constructed of ¾ inch thick PVC pipe, and closes via ball valves when the net closes. The net is remotely opened at depth, and while it is fishing, the ball valves at either end of the cod-end are open, and animals flow through the net into the cod end, where they are trapped in a mesh bag. When a signal is sent to close the net, the ball valves on the cod-end snap shut, trapping animals inside the cod-end in cold water at their normal ambient temperatures. The thick PVC walls insulate the water against temperature changes on the trip to the surface. The closed cod-end is also light tight. Once the net has been brought onboard, the closed cod-end can be detached from the net, carried into a light-tight room, and opened under dim red light.

How to study vision in deep-sea animals – Jonathan Cohen and Tamara Frank

How do we measure whether hydrothermal vent shrimp can see, or whether they are blind? When an optometrist tests your vision, they show you images and ask you questions. With shrimp we obviously need to take a different approach. One technique we use at sea is electrophysiology, which involves eavesdropping on the electrical changes in the neurons of the eye that absorb light energy and convert it into the electrical signals that can be picked up from the surface of the eye with an electrode. We could do the same thing with your eyes using a contact lens electrode, if you’d let us. By shining light of specific colors and intensities, we can understand the capabilities of the shrimp visual system. For animals living in the deep sea, very little light is needed to cause a visual response, and the sensitivity of eyes peak at blue wavelengths as these colors of sunlight extend deepest in the water column. At hydrothermal vents, there isn’t enough sunlight left for any animal to see, no matter how sensitive their eyes are. But, the hot water leaving the vents could create a light that shrimp eyes could detect. Or there may be bioluminescent organisms around vents that can be seen. Or minerals in vent fluid could create light. Or perhaps the infrared heat itself is a signal the eyes can detect. Our electrophysiology experiments will help us determine if vent shrimp eyes are sensitive to any of these various light signals.

Photo Caption: Three electrophysiology rigs ready to measure shrimp vision. Each one includes a metal box (Faraday cage) to block electrical noise from all the wiring on the ship, wrapped in a black cloth to keep the shrimp in the dark. A microscope inside the box helps guide an electrode to the correct position, and a temperature-controlled water bath keep the shrimp at its normal temperature of ~7° Celsius (~45° Fahrenheit). Light of specific colors and intensities are directed into the box and onto the eye with a fiber optic light guide, while an electrical amplifier magnifies the electrode signal of cells in the eye responding to the light. A computer captures these signals, which we use to understand the visual capabilities of shrimp eyes. 

Studying and collecting hydrothermal vent shrimp with the HOV Alvin – Tamara Frank and Jonathen Cohen

The tool that we’ll be using to study hydrothermal vent shrimp is a research submersible called Alvin.  It is an HOV, which stands for Human Occupied Vehicle, as opposed to an ROV, which stands for Remotely Operated Vehicle.  Owned by the U.S. Navy and operated by the Woods Hole Oceanographic Institution, it is the world’s longest-operating crewed deep-sea research submersible.  Research submersibles have gotten a bad reputation because of the horrific accident with OceanGate’s Titan submersible.  The Alvin, which has been operating for five decades, has an unblemished safety record because of the rigorous certification and testing that is undergoes, processes that were sadly lacking with the Titan.  Capable of going to 6500 meters (~4 miles), it is operated by a highly trained and skilled pilot, allowing the two scientists onboard to conduct their observations and research.  It is much safer to dive in the Alvin than it is to drive in Florida.  Alvin is in constant contact with the support vessel, the RV Atlantis, and should contact be lost for some reason, Alvin immediately returns to the surface. 

Copyright: WHOI

With seven reversible thrusters, the Alvin can hover in the water or rest gently on the seafloor. One of the big advantages of diving in a human-occupied vehicle is that the scientist can see the surrounding environment, not just the region being imaged by the camera, and direct cameras and measurement probes to that location.  The cameras include two pan & tilt-mounted Deep Sea Power and Light 4K ultra-high-definition cameras along with a real-time 4K video recording system. There is also a Go-Pro Hero 11 with telephoto capabilities that make for stunning close-up images of whatever we want to film. In addition to cameras, there are probes and sampling equipment to measure temperature, oxygen, water, and organisms.

We will be using the Alvin to collect hydrothermal vent shrimp without damaging their eyes by filtering some of the lights on the Alvin with blue or red filters.  We already know that the bright white unfiltered light on submersible can irreparably damage the extremely sensitive eyes of deep-sea shrimp, so the light needs to be filtered. The animals will be collected with a slurp gun which gently suctions up the shrimp and deposits them into a chamber that has been blacked out so they are not exposed to light at the surface.  The Alvin also has a platform upon which we can install equipment (up to 400 lbs. out of the water) to help with our research.  This includes water collectors for studies of e-DNA and a variety of baited traps that will be deployed with the claw on the Alvin to collect some of the shrimp on the periphery.  The traps will be deployed at the beginning of the dive and then collected near the end of the dive.  Some of the traps are made of thick PVC for temperature insulation and can be closed at depth.  These are held open with magnesium links.  Magnesium dissolves in seawater, so after a certain amount of time (depending on the thickness of the link), the traps will close, ensuring that animals inside will be protected from light and temperature changes on the trip to the surface.  The other traps are open, and will be collected under red or blue light, and then deposited into a temperature insulated black BioBox, also protecting them from light exposure at the surface. In addition to the traps, we will try to sample larvae of vent shrimp in the water column with very small plankton nets attached to the Alvin.   

We will also be looking for bioluminescence at the vents  by gently tapping anemones and soft corals that we see from the sub.  If they bioluminescence, they will be collected for laboratory studies.  In addition, bioluminescence in the plankton hovering around the vents will be examined with a screen attached to the Alvin.  Contact with the screen causes any bioluminescent organisms to bioluminescence, giving us an idea of the amount of bioluminescence in the water around the sub.

Measuring source of light at the vents – Sonke Johnsen

A pelagic shrimp (caught in a trawl net) giving off a defensive biolumineschent spew

My lab’s job in this expedition is to understand and document the sources of light at the vents. So far as we can tell, there are three possible sources. First, there is light generated by the heat of the vents themselves. The water coming out of the vents is extremely hot. Because of the high pressure at depth, it can actually get much hotter than the usual boiling point and has been measured as high as 450° C! All things of any temperature emit light. Even we do, but only in what is known as the infrared portion of the spectrum. The vents are hot enough to emit light that can be seen. It’s dim, but it’s there. Light can also be made at the vents by something known as triboluminescence. This is light that is produced by the bending and breaking of crystals. The most famous example of this is the wint-o-green lifesaver candy, which makes blue sparks in your mouth when you bite on it. The vent fluids do eject all sorts of minerals, so this form of light is possible. Finally, there may be bioluminescence at the vents. We expect to find this in two different populations of animals. First, the animals that live on the vents might themselves be bioluminescent. Second, there may be bioluminescent animals in the plankton that run into the chimneys and hot water and then are stimulated to glow, much like mosquitoes in a backyard bug zapper.

So how do we study this? We do this in two primary ways. First, using the Alvin submersible, we take movies in the dark of the chimneys and vents to see if we can find any light. Some of these movies are taken while the submersible drives forward with a large screen in front of it. Bioluminescent animals will glow if they hit this screen, which always makes me think of bugs on a deep-sea windshield. We also can see if individual animals glow by touching them with the claw of the submersible while the lights are off and seeing if we can induce any of the animals to glow.

Some of the animals will be collected by Alvin and brough to the surface, where they will be touched in the dark to see if they glow. If they do, we will take photos of this light. We will also use a specialized instrument called a spectrometer that will measure the color of the emitted light in a precise way. This information can tell us a lot about which animals can see this light and how far it can travel through the water. During the last cruise to the Azores, we did not find any bioluminescent animals, so this year we are at a different site in the Caribbean to see what we find there.

Using genomic methods to determine what hydrothermal vent shrimp can see - Heather Bracken Grisson

Opsins are light-sensitive G protein-coupled receptors (GPCRs) that form the molecular basis of vision and many non-visual light-sensing processes in animals. They play central roles in photoreception, circadian rhythm regulation, camouflage, and communication using bioluminescence. Because opsin gene families are often large, highly divergent, and differentially expressed among tissues and developmental stages, transcriptomics has become one of the most powerful approaches for identifying and characterizing opsin diversity across taxa.

Transcriptomics uses high-throughput RNA sequencing (RNA-seq) to capture the complete set of expressed genes within a tissue or organism at a particular time. Unlike whole-genome sequencing, which identifies all genes regardless of their activity, transcriptomics focuses on genes that are actively transcribed (expressed). This is particularly advantageous for opsin discovery because photoreceptor tissues such as eyes or extraocular photoreceptors often express opsins at relatively high levels, facilitating their detection even in species lacking reference genomes.

The workflow begins with the extraction of high-quality RNA from light-sensitive tissues (in our case from the eyes or predicted photosensitive tissues) followed by library preparation and next-generation sequencing. Fragmented sequencing reads are then assembled back together much like a puzzle using bioinformatic techniques. Protein-coding sequences are predicted from assembled transcripts and searched for candidate opsins using sequence similarity searches. Following identification, phylogenetic analyses are used to classify candidate opsins into established families such as rhabdomeric (r-opsins), ciliary (c-opsins), Go-opsins, neuropsins, peropsins, xenopsins, and others. Phylogenetic reconstruction is essential because sequence similarity alone is often insufficient to distinguish between closely related opsin classes or identify lineage-specific duplications. In this study we are particularly interested in opsins known to play a role in light detection, which we refer to as visual opsins.

We are asking the question: are hydrothermal vent shrimp blind or can they detect light?  If so, which wavelengths (long, middle, short) are they most sensitive? 

Transcriptomics has substantially advanced our understanding of visual evolution, particularly in non-model organisms. In marine systems, for example, transcriptomic studies have uncovered unexpectedly diverse opsin repertoires in crustaceans, cephalopods, fishes, and cnidarians, revealing repeated gene duplication, functional diversification, and spectral tuning associated with different light environments. Comparative transcriptomics has also demonstrated that species inhabiting deep-sea, cave, or nocturnal environments often exhibit shifts in opsin expression or gene loss that reflect adaptation to low-light conditions. Furthermore, integrating transcriptomic data with ecological, behavioral, and physiological studies has provided new insights into the evolution of color vision, polarization sensitivity, and bioluminescent signaling.

Despite its strengths, transcriptomics has limitations. Because only expressed genes are detected, opsins with low or temporally restricted expression may be missed. Gene expression can also vary with circadian cycles, developmental stage, environmental conditions, or tissue sampling, making experimental design critical. In order to confirm functionality, the translation of the expressed gene to protein, it is imperative we combine transcriptomic results with other methods.  In this project we are using techniques like histology, in situ hybridization and immunohistochemistry so that we can confirm functionality. 

Overall, transcriptomics has become an indispensable tool for exploring vision in a variety marine and terrestrial taxa and we are now interested in how hydrothermal vent shrimp perceive their world. By combining gene expression and phylogenetic analysis, transcriptomic approaches provide a comprehensive framework for investigating how visual systems evolve and adapt in extreme environments.