April 2014 – Glaspie Lab

April 24, 2014June 21, 2018

Dr. Shipworm, Ph.D.

Bow section of a shipwreck visited by NOAA Okeanos Explorer on April 20, 2014. Image from NOAA Okeanos Explorer Program, Gulf of Mexico 2014 Expedition.

From April 17th 2014 through May 1st 2014, the National Oceanographic and Atmospheric Administration (NOAA) has brought together a team of scientists and engineers to explore the bottom of the Gulf of Mexico using their ship, the Okeanos Explorer, and their remotely operated underwater vehicle (ROV) named the Deep Discoverer. To the delight of science lovers across the nation, NOAA has been streaming live camera feed from their ROV for anyone to watch, greatly reducing the productivity of marine scientists and nautical archaeologists. On Thursday April 27th the Okeanos Explorer visited two shipwrecks in the Gulf of Mexico (click here to see the highlights). They discovered a variety of “encrusting biology” (animals that live on the hard structures of shipwrecks), archaeological treasures, and even the chronometer (timepiece) and the octant (a navigation device) of the early 19th century ship, which has led me to coin my new favorite phrase for use when facing impossible odds, “It’s like finding an octant in a shipwreck.”

If you watched the feed from the Monterey C shipwreck, you may have noticed one major thing missing from much of the ship’s debris field- wood. Since wood from a shipwreck is pretty much the only organic material in such a harsh environment as the deep sea, a lot of the wood from the ship had long since been eaten away by animals that feed on wood. Wood is not an easy thing to eat. It is full of fiber and difficult for the gut to break down. Even animals that have special guts for digesting plant matter, such as cows and other ruminants, cannot break down wood. In the ocean there is one fairly common critter that can eat wood. They are called shipworms.

Photo of a shipworm extracted from its burrow. Photo by USGS via Wikimedia Commons.

Shipworms are not worms at all. They are actually bivalves, a name that comes from the latin class Bivalvia. All of the members of the class Bivalvia have two (bi) shells (valves) that are hinged. Examples would be clams, oysters, scallops, and mussels. However, shipworms do not look like clams at all. They look more like worms, with long, fleshy, cylindrical bodies. They use their shells not for protection, like a clam or oyster, but to bore through wood. They can be a few centimeters long, or as long as a meter depending on the species, and they live in the burrows that they carve out of wood. The wood shavings are also consumed as food. The shipworm uses substances called cellulases to break down the wood, allowing them to extract nutrition from the tough fiber. This ability allows shipworms to join only a few known species that are capable of digesting wood, including protists, fungi, bacteria and a handful of species in several different invertebrate groups, including termites.

Shipworm burrows in a piece of wood. Photo by Wilson44691 via Wikimedia Commons.

Just as termites can cause problems for homeowners, shipworms can cause problems for people whose livelihoods depend on the sea. Shipworms are responsible for destroying ships and piers around the world. They also eat shipwrecks, which in many parts of the world are an important part of history and heritage. The shipworm’s tendency to nibble away at nautical history means they are mostly viewed as pests that need to be eradicated. There are a few marine environments in the world where shipworms are not found. One is the Antarctic, which is protected from shipworms by the circumpolar currents which act as a barrier to shipworm movement. The Baltic Sea, which is too fresh for shipworms to survive, has been protected from shipworm feeding in the past. This shipwreck oasis is now in trouble because recently shipworms have begun to invade the Baltic. An eradication program has begun to prevent the shipwrecks from becoming mollusk food.

Diagram of the tunnel shield used to build a tunnel under the Thames River. 19th century image, probably from the illustrated London News, via Wikimedia Commons.

I understand the need to protect historical wrecks. However, far from considering shipworms as a pest, I propose we celebrate the shipworm as a genius. In fact, I suggest we award the shipworm an honorary degree in engineering. Here’s why. The shipworm has played a major role in helping humans discover solutions to two major engineering problems over the last two hundred years. Have you ever wondered what it takes to make a tunnel under a river? I know I have. Turns out it is not easy. Tunnels in soft sediment, like the mud under a river, tend to collapse as they are built. In the early 1800s, Marc Isambard Brunel solved this problem with a little help from the shipworm. He observed a shipworm’s tunneling behavior. The shipworm bores through the wood and as it makes its tunnel, it encases the tunnel walls in shell material to prevent the wood from swelling, closing the tunnel and crushing the worm. Brunel designed a tunneling shield, which was an iron cylinder that was pushed further and further into the tunnel as it was excavated, preventing the walls from collapsing in on the workers. In this way he was able to make the first tunnel under the Thames River, and it was all thanks to the shipworm.

A field of Miscanthus (elephant grass) being grown for biofuel production. Photo by David Wright via Wikimedia Commons.

A more recent example of the shipworm’s prowess as an engineer is the quest for the fuel that will replace fossil fuels. The energy crisis has led us to look at biofuels, or fuels derived from living organisms, such as plants. The production of biofuels involves collecting sugars from plants and fermenting those sugars to make ethanol. However, plants store glucose in a tough fiber called cellulose. Getting the glucose out of cellulose is costly, making biofuel production from plants costly as well. A lot of recent biofuel research has aimed at reducing the costs associated with removing glucose from plant tissue. I am sure you can see where this is going. Shipworms have already solved this problem by developing an association with bacteria that live in shipworm gills and digest cellulose. In fact, some shipworms appear to live off of wood alone, and do not grow any faster when provided with extra food. These bacteria are being cultured for use in biofuel production. Perhaps in a few years the shipworm will have helped us solve another complicated engineering problem, improving human lives.

Is the shipworm an irritant or an inspiration? Shipworms have experienced an interesting evolutionary path to fill a unique niche, and they have developed the ability to eat a substance that is extremely abundant, but useless as a food source for the vast majority of other animals. This path has unfortunately led the shipworm to torment ship-owners and owners of waterfront property. It has also led to some of the most amazing achievements in engineering in the last two hundred years. This is the reason I think the shipworm deserves an honorary degree in engineering, and I hope this interesting animal will continue to inspire the great thinkers of my generation as we tackle increasingly difficult environmental issues.

For more information:

Honein, K., G. Kaneko, I. Katsuyama, M. Matsumoto, Y. Kawashima, M. Yamada, and S. Watanabe. 2012. Studies on the cellulose-degrading system in a shipworm and its potential applications. Energy Procedia 18:1271-1274.

Asfa-Wossen, L. 2012. Tunnel vision. Materials World, 20(5):10.

Tanimura, A., W. Liu, K. Yamada, T. Kishida, and H. Toyohara. 2013. Animal cellulases with a focus on aquatic invertebrates. Fisheries Science 79:1-13.

Miller, R.C., and L.C. Boynton. 1926. Digestion of wood by the shipworm. Science 63(1638):524

Gregory, D. 2010. Shipworm invading the Baltic? The Nautical Archaeology Society 431.

April 17, 2014June 21, 2018

A day in the life

Drawing from original draw-a-scientist study in 1983. Photo By Yewhoenter via Wikimedia Commons.

At the beginning of my graduate school career I remember sitting in on a seminar about a recent program implemented by several students called “draw a scientist”. Students involved in a GK-12 program, where graduate students bring science to middle school and high school classrooms, were asked to draw their version of a scientist. In the drawings, crazy hair, flasks, and lab coats were a common element. Students described their scientists using adjectives like smart, crazy, chemicals, mixing, nerd, weird, lab coat, old, lab work, hard-working, and cool. At that age, I probably would have drawn the same thing, except my scientist would have been female, and I would have most definitely included the word “cool” in my description. However, my experience as a scientist has not led me to don a lab coat very often. I have held a few jobs that included pristine labs with white, crisp coats and flasks, but more often than not, I am wearing muddy waders, hiking boots, or dive suits.

I am a marine scientist, and I study the interactions between animals that live in the ocean. Right now I am studying predator-prey interactions in the Chesapeake Bay, which is not exactly the ocean but it is pretty salty. It is an estuary, where the rivers from the land meet the ocean and a mix of fresh and salt water occurs. The Chesapeake Bay is home to many species found in the Atlantic, as well as some that are only found in estuaries. I am focusing my research on two predators, the blue crab and the cownose ray, and a few of their prey species, including the soft-shell clam (steamers in New England), hard clams (or quahogs), razor clams (often used as bait), mussels, and Eastern oysters. My research is attempting to answer the question, how will these predator-prey interactions change in the future as climate change impacts the Chesapeake Bay in various ways?

Scientists never really prove anything; they can only provide supporting evidence for a phenomenon, and as the amount of evidence grows, so does the scientist’s confidence that their answer is correct. Thus my research project that I am completing for my PhD will collect a variety of evidence to answer my research question. I have to look at the problem in a number of different ways, using not only experiments in the laboratory, but also observations and experiments from the Chesapeake Bay itself, and predictions from mathematical models. That is why getting an advanced degree in science takes so long and involves so much work. Scientists-in-training are learning how to build a body of evidence to try and answer a research question. When completed, my dissertation will consist of four different chapters which summarize eight (or more) research projects, all designed to provide some evidence pointing towards the answer of my research question. In the end I still won’t have an answer; just a starting point and a hundred more questions. Remember, science is a journey.

Suction sampling using a large pump to collect clams.

So what do I actually do? In the summer I go out on some rivers that feed into the Chesapeake Bay, like the York River, in a small boat and collect samples in shallow water. Most of my samples are suction samples. To take these samples I use a large pump that works as an underwater vacuum, allowing me to vacuum up the mud and sand on the bottom of the river. I use these samples to understand how many clams are in an area. I also tow nets behind the boat to collect fish and crabs (the predators in the area), and snorkel along a 50 m rope laid out on the bottom of the shallow parts of the river to count the pits that rays make when they feed. This is a much easier way to figure out how many rays are in an area than actually catching the rays.

Photo from a clear-water day in the Chesapeake Bay.

The water is mostly muddy but every so often, when the conditions are right, I feel like I am snorkeling in the tropics. Those are the best days, when I get to see vast expanses of seagrass, the terrapins (a type of swimming turtle that gets about the size of a dinner plate) swim next to me, and I can see all of the little clams and worms on the river bottom going about their business, excavating burrows and spewing out streams of mud that look like something that comes out of a Play-Doh pasta factory. But most days I can only see about a foot in front of my face, and the view is frequently obstructed by translucent jellyfish tentacles that appear too late for any sort of evasive maneuver, and the resultant burning pain is just treated as part of the overall experience. Hey, it could be worse. We could be in our office.

For the rest of the year I devote my time to a number of activities. These include sorting through the suction samples to pick out the clams, holding an active leadership role in graduate student government, keeping up to date on the latest science discoveries in my field, fulfilling my current funding requirements (this year, I was a guest scientist in a 7^th grade classroom for a couple of days every week), writing grant proposals to fund my education next year, writing reports (and soon my own scientific articles to be published in a journal), and working on a project in the seawater laboratory (see video).

I visit the seawater laboratory every day of the week, devotedly, except for Sunday. All of my critters (blue crabs, clams, mussels, and oysters) seem to behave on Sunday. However, if I fail to visit any other day of the week, disaster abounds. I return to rampant cannibalism (in the blue crab tank, of course), escapees, clogged plumbing, leaky ceilings, broken water heaters, overflowing tanks, you name it. For a while I was convinced that the brand-new seawater laboratory was haunted. Now I know that this is just one of the things that makes ecology so interesting and exciting. Since I am always working with live critters, things never really go as planned. I have spent most of my time in graduate school anticipating the evil intentions of invertebrates, some of which don’t even have brains. As a result I have had many chances to exercise creative, out-of-the-box thinking, and when I fail, the consequences are usually pretty hilarious.

I mark clams with marker before placing them in the river, so if I get them back I know they are from my experiment.

For instance, last summer I was running an experiment in several tanks where crabs were offered clams for food. There were various scenarios that made it harder to get at the food (i.e. clams were hidden underneath a layer of shell), and crabs are lazy, so it shouldn’t surprise me that the crab starring in this story had had enough, and was ready to strike out on his own to find a more promising food source. Despite precautions to prevent this type of thing from happening, the crab climbed out of the tank and into an adjacent tank. This rarely happens; the tanks are round and only overlap for a small portion, but in this case the crab was on a mission and the result certainly paid off. The day before I spent 8 hours with a volunteer painstakingly marking clams and placing them in containers to be deployed in the York River the next week. The crab had discovered a buffet of epic proportions, and the next day I arrived in the lab to find shell splinters and an extremely well-fed blue crab.

Catching a carp for fun while on the job.

My experiences may not be typical of the average scientist, but I would argue that white lab coats are not typical of the average scientist, either. Scientists are just as likely to be “outdoorsy” as they are likely to be holding chemicals over a Bunsen burner. Programs like GK-12, sponsored by the National Science Foundation, help to inspire the next generation of scientists and to change the way people think of scientists. As a result these programs produce a more diversified next generation of scientists, and hopefully increase public trust in science programs. This is especially important because public trust in scientists is very low. This should be very concerning for scientists, a group of people who base their lives and careers on a quest for truth.

April 14, 2014June 21, 2018

Not-so-streamlined science

Front view of a longhorn cowfish. Photo courtesy of I, Drow male via Wikimedia Commons.

Welcome to the Cowfish Blog! You may have heard of a cowfish before, or maybe not, but two things are certain- cowfish are REAL and they look strange compared to most fish. I figured I would introduce my mascot in this first post, and in doing so tell you a little bit about this blog, and science in general. So first, let me introduce my guest of honor, the cowfish.

You may notice a couple of things about the cowfish that stand out as strange. It is shaped like a box. That boxy shape is made of bone, which makes the cowfish much larger than would be necessary to simply contain its innards. This makes the cowfish, which tops out at about 20 inches in length, one of the largest fish around on the coral reefs, where it makes its home. That is excluding the sharks. And the groupers. In any case, it is large, which means it is noticeable if you go snorkeling in the Indopacific, especially because it is bright yellow. Its coloration makes it stand out to tourists, and also to predators. The cowfish doesn’t have to worry about standing out to predators because it has a couple of ways to defend itself. First, it has horns. These horns make it too large to fit in the mouths of most fish, which means only very large predators can hope to make a meal of a cowfish. Second, it is toxic. When a cowfish feels threatened it secrets poison from its skin, and this poison is very dangerous to other fish. This means that a shark that bites down on a cowfish might seriously regret the meal. Cowfish poisoning will first cause disorientation and erratic movements, then coma, then death. It is even toxic to mammals, though it takes a lot of toxin to affect humans. Cowfish toxin can have an indirect effect on humans that keep fish in aquaria, and have a sick cowfish kill an entire tank of fish in a night. Speaking from experience, of course.

I think most people would agree that a cowfish looks like a very slow swimmer. In fact, cowfish are fairly fast swimmers that can swim long distances using little energy and with great stability. They swim using movements from their fins only, since they can’t bend their bodies. At slow speeds the tail is used for steering, like a rudder. Their body shape can automatically correct any tips and dips that happen when waves sweep over the coral reefs on which they live. That is because all of the edges of a cowfish’s boxy frame stick out in a flat plate similar to the keel of a boat. Boat keels are designed to keep the ship stable in the water and to help prevent it from tipping over, and a cowfish keel works the same way. In addition to providing stability, all of the protrusions on the cowfish’s body interrupt water flow from pretty much any direction and push the water away from the cowfish, making for a smooth ride. This is similar to what happens to a delta wing aircraft in flight. Delta wing aircraft are designed for maneuverability, and so, it seems, are cowfish. Cowfish can turn on a dime and swim upside down, which are adaptations that allow them to explore all of the hiding places in a coral reef. As I mentioned, cowfish are also extremely enregy efficient swimmers. Boxfish (a relative of the cowfish) use about as much energy while swimming as a sockeye salmon, a fish built for traveling long distances. In fact, cowfish swimming is more efficient (at pretty much all speeds) than the smallmouth buffalo fish, a carp that lives in the Mississippi River and has a much more typical fish shape.

The cowfish body design is so efficient that engineers often turn to the cowfish for inspiration. One application of the cowfish body shape could be a more energy-efficient design for a stable underwater vehicle. DaimlerChrysler AG actually designed a concept car based on the body shape of the cowfish and its relatives. This car, called the Mercedes-Benz Bionic, was introduced as a highly energy-efficient vehicle in 2005. It can go from 0-60 mph in 8 seconds, which is 0.1 seconds LESS than the Jaguar S Type 2.7d V6 Sport introduced in 2004. Clearly there is a lot that can be learned from the cowfish.

One thing we often don’t think about (or maybe you do, in which case you MAY be a biologist) is how did the cowfish get this way? Over evolutionary time (we are talking hundreds of millions of years) fish are exposed to different pressures that they must be able to survive in order to persist as a species. These include predators, finding food, finding mates, and a variety of other things. So which of these pressures caused the cowfish to look the way it does, and why did it respond to these pressures differently from every other fish? Certainly other fish can avoid predators by hiding or using camouflage, and it seems like the cowfish sure wastes a lot of energy developing its bony armor and toxins when it could have just covered itself in camo. There are plenty of other fish on the reef that are masters of maneuverability, such as the wrasse, and these fish don’t have to build up a boxy shape to accomplish amazing feats of hydrodynamics. So what caused the cowfish’s ancestors to develop its unique shape, horns, and toxins? Perhaps we will never know, but we can imagine that the route from a normal fish-shape to the shape of my most recent Amazon delivery was probably not a direct one. If it was, we would likely see it a lot more often in the animal world. I, for one, am glad that the cowfish’s ancestors took such a circuitous route to become the unique species it is today, not only because I appreciate cowfish for their adorable appearance, but also because I look forward to the day when I can travel underwater in a submarine built like a cowfish. Which may or may not be yellow. But I really hope it is yellow.

This leads me to the reason for naming my blog after the cowfish. The cowfish embodies many of the reasons why I love science. Science is weird and full of questions. You can spend your entire life as a scientist asking and attempting to answer questions. However the answers, when you do get them, are usually not direct, much like the evolution of the cowfish. As a result the quest for answers is a journey that leads the scientist to strange and interesting places. The end is something you probably never expected, but it is also immensely more interesting than you expected. I love that about science, and I love that about the cowfish. So stay tuned for some more not-so-streamlined science- my experiences as a marine scientist, and interesting tidbits about science and the natural world.

For more information:

Bartol, I.K., M.S. Gordon, M. Gharib, J.R. Hove, P.W. Webb, and D. Weihs. 2002. Flow patterns around the carapaces of rigid-bodied, multi-propulsor boxfishes (Teleostei: Ostraciidae). Integrative and Comparative Biology 42:971-980.

Thomson, D.A. 1964. Osctacitoxin: An ichthyotoxic stress secretion of the boxfish, Ostracion lentiginosus. Science 146(3641):244-245.

Gordon, M.S., J.R. Hove, P.W. Webb, and D. Weihs. 2000. Boxfishes as unusually well-controlled autonomous underwater vehicles. Physiological and Biochemical Zoology 73(6):663-671.

Bartol, I.K., M. Gharib, P.W. Webb, D. Weihs, and M.S. Gordon. 2005. Body-induced vertical flows: A common mechanism for self-corrective trimming control in boxfishes. The Journal of Experimental Biology 208:327-344.