No Bones

IS IT A SMALL WORLD AFTER ALL?

Imagine you’re in the car on a rainy day looking out the window. What do you see? Then, pull your focus back to window itself and the raindrops beading up. Now what do you see? An entirely new world, right? Smaller, but a world just the same, individual droplets all interacting. A world you might not have even noticed was there, if you hadn’t looked closely.

It was a discovery, much like that classic raindrop riddled one from childhood, that rocked our world in the Department of Invertebrate Zoology (IZ) AquaRoom just a few short weeks ago. Looking in at the Cassiopea jellyfish and octocoral being cultivated inside the AquaRoom’s 55 gallon saltwater tank, it was all too easy to miss what was, quite literally, right under our noses; but, with the help of time lapse photography zoomed in to focus on the tank glass, an entirely new world was revealed. One of flatworms, isopods, and placozoans - each with a presence larger than life once given the spotlight.

An animated GIF by IZ Intern Alia Payne, depicting the organisms found on the tank wall.

It was in early February that a species of distinctly orange flatworm seemed to randomly appear. Curator Allen G. Collins first noticed the tiny organisms twisting and turning on the tank glass, and with IZ interns Lauren Thomas, Allie Straus, and Kela Bakari hard at work studying individuals under a microscope and thinking through important questions on what makes these captivating creatures tick, the AquaRoom team is making some exciting steps towards grasping the complexity of this tiny world. Armed with a Nikon D7200 camera and 60mm lens shooting 1 image every 3 seconds, the interns are capturing time lapse videos like this one that we hope will enable new insight into these organisms’ activities. There’s so much more to that 55-gallon tank than meets the eye!

In this video you can see a sampling of the countless interactions happening every moment at this microscopic level!

“I think our flatworms should have a Youtube channel,” Lauren joked after I spent so long mesmerized by these animals sporting vibrant orange, and moody brown hues that I had worm-shaped spots wriggling through my vision. I was inclined to agree-- though the skittering isopods and translucent placozoans reminiscent of The Blob are something to behold, the fiery eye-catching flatworms steal the show. But what do we know about these invertebrates?

 

Well for starters, flatworms as a whole glide through their environment by moving hair-like structures known as cilia. They have bilateral symmetry, meaning they’re divided into two halves that are almost mirror images of each other. Surprisingly, the flatworms all used to be united within a single phylum, Platyhelminthes (quite literally platy- “broad or flat” helminthes - “worms”), but now we know that one group, Acoelomorpha, has a separate evolutionary history from the other flatworms. While many flatworm species are parasitic which, unfortunately for their microscopic roommates, means they take from another organism in a way that’s harmful-- such as living in or on the body of the organism they are feeding off of, acoelomorphs are free-living worms.

 

As for our AquaRoom Flatworms, after some literature searches, we concluded that our orange fellows belong to the acoelomorph species Convolutriloba longifissura. This is a species known to reach a maximum length of 6mm. [3] C. longifissura often eat brine shrimp and copepods, and they consume their prey like a vacuum, scooping it right up! [1] Though we relate to how flatworms down their meals, these organisms unlike us have no gut cavity to speak of-- their mouths open up directly into the main layer of tissue in their body. [3]  Speaking of food, their interactions with placozoans and other critters traversing the glass are especially interesting: In the time lapse above (and the cropped excerpt below), a flatworm appears to attempt eating a writhing worm that we initially mistook for a placozoan, but then rejects it just as quickly. While the flatworm recoils, the weird worm then seems to make its escape. One of our questions is whether this is a typical interaction between the two species. And of course we need to put that worm under a microscope to learn more about what it is.

This video depicts the mystery worm's harrowing encounter with the Convolutriloba longifissura.

So flatworms live on other organisms, feed off of them, or try to, but do they ever team up? Apparently, they do. Flatworms of Convolutriloba have symbiotic relationships with green algae that live within their tissue, and it’s these same green algae cells that enable the flatworms to naturally fluoresce. [3]

Though it remains a mystery how exactly these flatworms appeared in the tank, it soon became apparent how their numbers flourished so quickly. Flatworms reproduce asexually through division. What sets C. longifissura apart from other Convolutriloba species however, is the stages it undergoes during division. Through a transverse fission the flatworms posterior end splits off, and then within a 24-hour period, the posterior end splits in half via a longitudinal fission. Within 2-3 days, during which the two budding flatworms develop eyes and a mouth, what began as one individual flatworm has now become three. [2]

Of the genus Convolutriloba’s four known species, three of them have been named from specimens found on aquarium walls-- and placozoans were described from aquarium walls, as well. It seems as though we aren’t the only ones exercising our curiosity by staring at the glass walls of aquaria! These organisms may be minute and mysterious, but just like their Cassiopea tank mates, they are ambassadors of a remarkable natural world worthy of the up-close attention.

By-- Alia Payne and Lauren Thomas

FURTHER READING:
1. Åkesson, B., Gschwentner, R., Hendelberg, J., Ladurner, P., Müller, J., & Rieger, R. (2002, January 06). Fission in Convolutriloba longifissura: Asexual reproduction in acoelous turbellarians revisited. Retrieved from https://onlinelibrary.wiley.com/doi/abs/10.1046/j.1463-6395.2001.00084.x
2. Identification - macropyga. (n.d.). Retrieved from https://sites.google.com/site/macropyga/identification
3. Euichi Hirose and Mamiko Hirose "Body Colors and Algal Distribution in the Acoel Flatworm Convolutriloba longifissura: Histology and Ultrastructure," Zoological Science 24(12), (1 December 2007). https://doi.org/10.2108/zsj.24.1241

Powerful Florida Storm affects biodiversity

Powerful Hurricane Irma altered the marine fauna of Ten Thousand Islands, Florida as it blew through on Sept. 10, 2017.  One of the most prominent observations in its aftermath was the appearance of a marine invertebrate species that is not commonly found in this area, Molgula manhattensis. This species was found in high abundance attached to submerged mangrove debris and formed patchy mats on the sandy bottom of barrier island passes.

Molgula manhattensis belongs to the subphylum Tunicata (Urochordata) commonly referred to as tunicates or sea squirts. They are notable invertebrates (animals without backbones) because they constitute a subphylum of the phylum Chordata (animals with a notochord or backbone, such as ourselves); that is, they are our closest living relatives among the invertebrates. Sea squirts exhibit a backbone type structure called the notochord in their larval stage that is used for swimming to find an ideal location to attach.  Once they attach, the notochord is reabsorbed and shrinks to a simple nerve ganglion.  The animal then metamorphoses into an adult. While developing, a “tunic” or covering is formed for protection. The name tunicate comes from the outer covering. Tunicates are filter feeders, feeding on tiny particles especially bacteria from the water. They are found attached to all types of hard substrate including mangrove roots. Importantly for this story, there are no known freshwater species, all are marine (all live in seawater), but a small number of species are capable of living in brackish water.  

Mangrove branches covered with Molgula manhattensis

 

Molgula manhattensis, the species that appeared in large numbers after the storm, is of interest because there are no former records for the Ten Thousand Islands region, despite long-term research on the turtles that live there. Van Name (1945) indicated M. manhattensis occurred along the U.S. coast from Maine to Texas but its distribution appeared to be interrupted by the Florida peninsula. Regarding this discontinuity, however, Frey (1965) warns that “lacking really adequate data on distribution one must always be cautious that a presumed interruption in range reflects the actual condition in the species rather than merely the patchiness of fortuitous collections”. The latter appears to be the case with the perceived distribution in western Florida.

Published (Dragovich and Kelly, 1964) and online information indicate that M. manhattensis occurs as far south as Tampa Bay. The Department of Invertebrate Zoology database shows additional records from Charlotte Harbor, a major estuarine system south of Tampa Bay. The southernmost records (Captiva Pass in Pine Island Sound and the Caloosahatchee River) are only around 90-100 km north of the recent collection in Ten Thousand Islands. We have since received unconfirmed reports of sea squirts (most likely M. manhattensis) being collected during fish trawl studies in the backwater bays of the Ten Thousand Islands prior to the hurricane (P. O’Donnell, RBNERR, pers comm.). Collectively, these data suggest M. manhattensis has occurred cryptically in the less-saline backwaters throughout southwest Florida and it took a major hurricane to bring it out of hiding.

Prior to Hurricane Irma’s landfall, southwest Florida was already experiencing an excess of 15” of rainfall (138%) for year-to-date historical amounts. This amount increased to +24” (150%) after the storm’s passage. All the nutrient-rich freshwater draining into the estuaries and the churning of waters by Irma’s strong winds created hypoxic (no oxygen) conditions for weeks in the Ten Thousand Islands. M. manhattensisis one of the few sea squirts that will live in polluted, low-salinity waters (Van Name, 1945) so it makes sense that this species flourished after the storm. Now that conditions have improved, it will be interesting to see whether M. manhattensis continues to thrive in the outer zone of this estuary or retreats to obscurity in the backwater bays.

By Linda Cole – National Museum of Natural History, Dept. of IZ and Jeff Schmid – Conservancy of Southwest Florida, Dept. of Environmental Science

 

REFERENCES

 

Dragovich, A. and J.A. Kelly, Jr. 1964. Ecological observations of macroinvertebrates in Tampa Bay, Florida 1961-1962. Bulletin of Marine Science of the Gulf and Caribbean 14:74-102.
Frey, D.G. 1965. Other invertebrates-an essay in biogeography. In: H.E. Wright Jr. and D.G. Frey, The Quaternary of the United States. A Review Volume for the VII Congress of the International Association for Quaternary Research, pp. 613-632. Princeton University Press, New Jersey.
Van Name, W.G. 1945. The north and south American ascidians. Bulletin of the American Museum of Natural History 84:1-476.

Metal Medusae: Trace elements in the upside-down jellyfish Cassiopea

What comes to mind when you think of a jellyfish?  Stings?  Tentacles?  SpongeBob SquarePants with his net?  I like all of these answers, but after coming across some scientific studies, I’d add the elements copper, zinc, chromium, arsenic, and iron to the list.

Cassiopea are unique in their upside-down lifestyle. This is an upward view from under the soft mesh we use as a barrier between our delicate jellies and the intake of the water filter.

Researchers in Australia have discovered that the upside-down jellyfish can accumulate trace amounts of these METALS in its bell and oral arms, and these amounts exceed those in the surrounding seawater (Templeman & Kingsford, 2010).  The specific elements measured in their study were aluminum, arsenic, barium, cadmium, chromium, copper, iron, manganese, and zinc.  But if you’re now envisioning the ocean as a liquid wasteland, rife with old power wires and discarded toasters, be sure to read ahead before you cancel your next beach vacation.

Some beautiful shots of our AquaRoom inhabitants.

Some of these metals are actually ESSENTIAL TO LIFE: copper is in hemocyanin, the oxygen-delivery protein used by multiple invertebrates such as horseshoe crabs, octopuses, squids, lobsters, shrimps, and snails; iron facilitates oxygen transport in hemoglobin, the oxygen-delivery protein of vertebrates (like us!); chromium helps regulate our sugar levels; DNA function requires zinc; and manganese is present in our bones.  But as with many good things, too much = bad.  And although a good general principle is arsenic = bad, minute quantities of this notorious element may even be essential, too (Hunter 2008).

A section of the periodic table of the elements (Patti 2006), with the nine elements found in Cassiopea outlined in purple.

With such a delicate threshold between essential concentrations and harmful ones, keeping a sharp eye on these levels is quite important.  This is where the term BIOMONITOR comes into play.  Also known as a bioindicator or indicator species, this is an organism that can provide useful information about the surrounding environment.

Jellyfish have often been overlooked for this role.  To be an effective biomonitor, species should have a wide geographic distribution, be relatively sedentary, tolerant of physicochemical (physical/chemical) changes, be readily identifiable, and be able to accumulate elements of interest (Templeman & Kingsford, 2010).  But Cassiopea are unlike most jellyfish in these respects: in addition to their expansive coastal marine environments, Cassiopea ARE relatively sedentary (they hang out upside-down on the ocean floor), and this trait also makes identification easy; they are EURYHALINE (your word of the day, meaning they can tolerate water of varying saltiness); and from the studies, it’s evident they can retain metals that have significant importance to life (Templeman & Kingsford, 2010).

This aerial shot demonstrates how Cassiopea are easily identified.

But why not just sample the water itself?  Why is a biomonitor so important?  While directly measuring contaminants in the water can be helpful, getting this information from a living creature provides much more relevant data in terms of how these contaminants affect the organisms and their ecosystem (Epstein et al. 2016).  What’s more, these metals can accumulate as they are passed up the food chain, posing potential risks to larger predators and, eventually, us!  This accumulation is not apparent when only sampling the water.

And one more very cool thing: researchers were able to use a jellyfish’s metal composition to determine where it came from  (Templeman & Kingsford, 2010)!  The animals were collected from one of five locations in Australia, ranging from the continent’s north coast to its east coast, which is about 1700 miles (2700 kilometers)!  For any fans of forensic science shows, this reminded me of investigators tracking where an item was purchased based on its UPC code, or where soil found at a crime scene could have originated.  Perhaps someday soon a jellyfish will be entered as a piece of evidence because of what metals are found in its bell.

Who knew jellyfish were such metalheads?

By Daniel Jackson

References

Epstein, H. E., Templeman, M. A., & Kingsford, M. J. (2016). Fine-scale detection of pollutants by a benthic marine jellyfish. Marine Pollution Bulletin, 107, 340-346. http://dx.doi.org/10.1016/j.marpolbul.2016.03.027

Hunter, P. (2008). A toxic brew we cannot live without. Micronutrients give insights into the interplay between geochemistry and evolutionary biology. EMBO Reports, 9(1), 15–18. http://doi.org/10.1038/sj.embor.7401148

Patti, S. (2016). Period Table of Elements [Open-source computer software]. Retrieved from https://sourceforge.net/projects/periodic-table-of-elements-qt/

Templeman, M. A., & Kingsford, M. J. (2010). Trace element accumulation in Cassiopea sp. (Scyphozoa) from urban marine environments in Australia. Marine Environmental Research, 69, 63-72. Doi:10.1016/j.marenvres.2009.08.001

 

 

 

 

Creatures from another world right under your nose

The vast world of invertebrates encompasses some truly beautiful and bizarre creatures, animals so exotic-looking that you’d only expect to encounter them in the deep regions of underwater realms.  But many would be surprised to know that the National Museum of Natural History houses LIVING jellyfish in the 2^nd-story region of its terrestrial Invertebrate Zoology department.

These animals do not mind living amongst the webs of algae, and their hardiness make them ideal creatures to care for and study.

That’s correct—within the labyrinth of hallways and staff offices, nestled amongst the specimen collections and laboratory space, there exists the AquaRoom.  Inside, dozens of jellyfish reside in a series of aquariums, the largest of which holds 55 gallons of saltwater (mixed by hand with Instant Ocean salt, deionized water, and intern elbow grease).  And by far the most bountiful of our lovely lifeforms belong to the genus Cassiopea, commonly referred to as the upside-down jellyfish.

While called the upside-down jellyfish, these animals do not always remain so oriented. Here we see one individual breaking from the norm as it hovers over its fellows like a mothership.

Cultures of Cassiopea jellyfish are relatively easy to maintain and propagate.  Personally, the only prior experience I had with aquariums was owning a few kinds of pet-store fish, but fellow intern Christine Martin and I have succeeded in caring for these magnificent animals over the last year, allowing them to grow in size and reproduce.  Regarding size, these animals are typically 1/16-1/8 of an inch (.16-.32 cm) in diameter when they start swimming around as babies; however, our largest jellyfish currently has a diameter of around 5 inches, or 12.7 cm (a conservative estimate).  This means some of the baby jellyfish we received in 2014 have increased 40- to 80-fold in size since the AquaRoom started regularly keeping marine invertebrates!

Some of our largest Cassiopea; the jellyfish on the right is approximately 5 inches across! This is an aerial view, making it easy to see why these are called upside-down jellyfish.

And Cassiopea are not the only aquatic occupants lurking in our AquaRoom, either.  We also maintain cultures of box jellyfish (class Cubozoa), care for an impressive octocoral (class Anthozoa), and look after several other Cnidarians that we periodically receive from institutions such as the National Aquarium, although these species usually require more intensive care than our upside-down jellyfish.  Currently the primary jelly care-taking reigns have been handed over to Christine, and she would definitely be the best person to speak with if you’d ever want to take the AquaRoom tour!

One of the AquaRoom’s other inhabitants: a box jellyfish (Class Cubozoa). This shows the stages of development as the polyp (upper left) metamorphoses into a juvenile jellyfish (bottom left). You can see how earlier the remarkable eye (with lenses, etc.) of the adult jellyfish develops early during the polyp metamorphosis (upper right). 

Observing these jellyfish in person borders on indescribable, but I will try anyway.  It is strange to develop such a level of respect and awe for a faceless invertebrate animal, not to mention one that lives in water while also being 95% composed of it.  Part of this connection may be a result of feeding and caring for them for months, but I believe the feeling has deeper roots.  To be face-to-face with a being so blatantly different and strange while knowing, consciously or otherwise, that they successfully and comfortably share the same world we do—that is a mind-bender.  If you are ever annoyed, saddened, or just bored by day-to-day life, maybe spend an afternoon with our jellyfish: it’s like visiting another planet, but without running out of oxygen, or getting too close to the Sun, or getting too far from the Sun, or crashing into an asteroid, or absorbing too much gamma radiation, or…you get it.

Another AquaRoom dweller, our lovely octocoral (Class Anthozoa, Subclass Octocorallia). At one point, one of this coral’s arms was knocked off, so we actually have an additional (albeit much smaller) coral that is doing just fine on its own!

In other words, there is a hidden dimension, beyond that which is known to the average Smithsonian museum visitor.  It is a dimension as vast as a small office and as timeless as 2014.  It is the middle ground between ocean and knowledge, between science and education, and it lies between the exhibit of Human Origins and the summit of the museum’s 3^rd floor.  This is the dimension of fascination.  It is an area which we call the AquaRoom.

 

By Daniel Jackson, IZ Intern

 

 

Tiny Jewels in the Ocean

In the group of marine animals known as echinoderms (from Greek, meaning “spiny skins”), there are five distinct groups alive today – the familiar starfish, sea urchins (including sand dollars), sea cucumbers, sea lilies, and brittle stars.   A beachcomber picking things up along the shore, or a deep-sea fisherman sorting his catch in a net, can usually tell at a glance to which group of echinoderms a specimen belongs, for the five main groups have fairly distinctive shapes. 

But, not always.

Figure 1. A typical brittle star. From Hendler, G. et al. 1995. Sea stars, sea urchins and allies. Smithsonian press.

 

There are about 2,000 species of brittle stars alive today, and most brittle stars are shaped like this (Figure 1), with a small central disc and five so-called arms.  But, in 1879, a British scientist, Dr. W.P. Sladen, discovered a strange little echinoderm, about half an inch across, that he at first thought was a starfish – it was certainly starfish shaped - but on further study, he was amazed to find that it was a brittle star.  He named this new genus Astrophiura, which might be translated to mean “starfishy brittle star”.  In the intervening 100 years and more, about eight additional species of this strange animal have been found, in various areas of the world’s oceans.  Until recently, though, none had been recorded from the Atlantic Ocean.

A few specimens, some in the collections of the Smithsonian’s Natural History Museum, and others that have been collected very recently in the vicinity of Curacao in the southern Caribbean, have proven to be Atlantic Ocean representatives of this weird starfishy brittle star, and I have named this new species Astrophiura caroleae in honor of Dr. Carole Baldwin, a Curator of Fishes in our museum, who founded DROP (Deep Reef Observation Project) several years ago, and whose dedication and enthusiasm has resulted in many new deep coral reef discoveries being made using a manned submersible, Curasub, which can dive to depths of 1000 feet and more.

Figure 2. From Pawson, D.L. 2018. Zootaxa 4378 (2).

 

Astrophiura caroleae, like its weird relatives, is about half an inch across, with a starfish-like central disc, and tiny fragile so-called free arms, which are usually broken off when individuals are collected.  This animal (Figure 2A, 2C, 2D) is usually easily visible because of its bright reddish color, and it adheres to hard surfaces, so it can be found attached to dead shells, pieces of coral, and man-made objects – such as discarded beer bottles (Figure 2B).

Does this little creature play an important role in the general economy of the deep sea?  Probably not.  It is seldom found, but it always excites interest and pleasure.  A tiny and beautiful jewel that challenges us to learn its secrets!

By Dave Pawson

Oh how you’ve grown! The Life Histories Program at the Smithsonian Marine Station, Fort Pierce, Florida

In 1972, Dr. Mary Rice made a decision that changed how biologists see the Atlantic coast. As the newly appointed director of a small marine station in Fort Pierce, FL, Rice decided to open her doors to the Smithsonian’s scientific community and research fellows, enabling them to expand their work from specimen collections, to in-depth studies of organisms in their natural habitats. At the station, Rice established the Life Histories Program, which tracks the growth and development of marine invertebrates. For Rice, the Smithsonian Marine Station became an ideal place to research these fascinating creatures and the transformations they experience as they grow from egg to adult. 

Mary Rice and Kevin Eckelbarger comparing specimens in the Life Histories lab in 1974, which was located on a barge on the campus of Harbor Branch Oceanographic Institute at the time.

Mary was most interested in sipunculans, or ‘peanut’ worms, a family of marine worms found worldwide from the shore to the deep sea. She studied the reproduction and development of the many sipunculan larval forms, and then compared them to the development of other worms, followed by more distantly related invertebrates. Through her research, Dr. Rice hoped to gain a better understanding of marine invertebrate development as a whole, and the role it plays in their ability to reproduce, disperse and adapt to different environments.

Mixed plankton sample showing a broad diversity and abundance of Gulf Stream animal forms.

Rice continued her research for 36 years, until her retirement in 2002. Eight years later, Michael Boyle arrived at the Smithsonian Marine Station, first to learn directly from Mary’s extensive experience (she was still working even though long retired), and most recently, as a staff scientist to manage the future course of research in the Life Histories Program. Like Rice, Dr. Boyle’s research focuses on the life histories of marine invertebrates, with a special interest in the evolution and development of sipunculans.

The Smithsonian Marine Station at Fort Pierce, Florida, as it looks today.

This research goes well beyond pure scientific curiosity. Throughout their life histories, invertebrates have a huge impact on the ocean ecosystems we rely upon to feed us and sustain our planet. The large animals we harvest are reliant on the tiny plankton as a food source directly or indirectly depending on their feeding strategies. Furthermore, many of the non-motile adult invertebrates, such as corals, oysters and even some worms, actually form reef structures that shield our coastlines from storms and erosion, simultaneously serving as habitats for all sorts of ocean life.

Compilation of photomicrographs of plankton specimens of various types and the mixed plankton tow sample they were collected from.

To gain a better understanding of the many roles marine invertebrates play in the ocean ecosystem, the Smithsonian began its StreamCode project. Inspired and coauthored by Michael Boyle and Karen Osborn, and with the passionate dedication of several Smithsonian scientists from the Department of Invertebrate Zoology (IZ) and NOAA’s National Marine Fisheries Service (NMFS), the StreamCode project is focused on documenting the stunning diversity of microscopic invertebrates in the water column along Florida’s Atlantic coast. With the Smithsonian Marine Station at Fort Pierce as a base of operations, this team of scientists has set out to collect zooplankton from the Florida Current region of the Gulf Stream.

Most of the June 2017 StreamCode participants (left to right): Allen Collins, Ai Nonaka, Chan Lin, Cheryl Ames, Kate Hansen, Michael Boyle, Karen Osborn, Elise Hartil, Will Jaeckle, Ellen Strong, Leann Biancani, Mike Vecchione, Robert Boyd.

With a multipronged approach using high-resolution photography, DNA sequencing of genetic ‘barcodes’, and detailed descriptions of microscopic diversity, marine scientists will begin to obtain a clearer picture of which planktonic invertebrates move with and survive in the Gulf Stream. 

Kate Hansen and Michael Boyle imaging and processing copepods collected during the June 2017 StreamCode expedition.

From the collections made for this study, more detailed life history studies will allow us to investigate the adaptations of these invertebrates to a broad assault of environmental challenges. Following in the footsteps of Dr. Mary Rice, Dr. Boyle’s efforts in the Life Histories Program, along with help from IZ and NMFS scientists, may give us a more detailed understanding of the development and dispersal of meroplanktonic animals as they surf the currents of the world’s open ocean.

Mary Rice and Michael Boyle in the molecular biology laboratory at the Smithsonian Marine Station at Fort Pierce.

 

By Robert Boyd, Department of Invertebrate Zoology Intern and Masters student at American University

Unsung Invertebrates: Stalked Jellyfishes

“Those who dwell among the beauties and mysteries of the earth are never alone or weary of life.” –Rachel Carson, The Sense of Wonder (1965)

Per usual, the words of trailblazing conservationist and marine biologist Rachel Carson are timelessly applicable. In the quote above, as excerpted from her award-winning composition The Sense of Wonder, Carson emphasizes the values rooted in straying away from what is familiar, and instead pursuing the unknown within the natural world.  Such a reflection analogizes the current conservation crisis of under-studied species such as the stalked jellyfishes, due to their inconspicuous identities. As a relatively obscure group in the world of science (until recently), stalked jellyfish populations have been inadvertently excluded from most conservation efforts, as their existence is often overlooked.

The stauromedusa Craterolophus convolvulus, nestled among the algae, by David Fenwick Senior

Belonging to the class Staurozoa, stalked jellyfishes are members of the Cnidaria phylum, specifically residing under the order Stauromedusae. Early in their taxonomic history, stalked jellyfishes caused some confusion as they were first misclassified as relatives of sea cucumbers, only to later be inaccurately associated with sea anemones (possibly because both organisms live attached to the seafloor). The absence of a medusa stage, in addition to the stalked jellyfish’s favored fixed orientation, provoked major deliberation as to its relationship to other cnidarians with free-swimming tendencies.

Using an adhesive basal disc as a holdfast to latch themselves onto boulders and rocky substrates, as well as onto sea grasses and aquatic plants alike, stalked jellyfishes usually inhabit rock pools and shallow tidal zones with environmental conditions that accommodate their sticky situation! Because species of stalked jellyfish maintain a lifelong sessile position, it is vital that the ecosystem in which they are affixed allows for adequate water circulation to regularly propel food sources into the jellyfishes’ reach. Equipped with nematocysts (stinging cells) stored within the cnidocytes of the tentacles located atop each of their eight “arms”, stalked jellyfishes fire these toxic darts to impair their prey, allowing them time to capture the stunned organism with their tentacles.                                                                  

Lucernaria sainthilairei on the rocks, by Alexander Semenov.

Despite the information collected thus far regarding the behavioral tendencies, anatomical structures, and ecological roles of stalked jellyfishes, the species still remain relatively unexplored. Yet in recent years, scientists have been working in a race against time to properly research individual species, providing scientific names and descriptions of “new” species (they aren’t really new, just new to science!) that lack a proper identity, prior to and in prevention of their untimely extinction. In fact, bringing these poorly known species into the scientific spotlight may be key to their conservation in an ever-changing environment under the pressures of human activities. Without exposure to the attention elicited by extensive research efforts, many species reside in an out of sight, out of mind void where no conservation efforts are made to protect them, solely due to their unsung status. In fact, no species of stalked jellyfish has ever been evaluated to determine if it is threatened or endangered [but see the exciting efforts being made by Stauromedusae UK].

While most stauromedusae are found in cold waters, a few such as this Calvadosia sp. are found in tropical waters. This animal was documented as part of the Moorea Biocode Project in French Polynesia.

As for knowledge about stalked jellyfish biodiversity, Dr. Lucília S. Miranda from the University of São Paulo in Brazil, has made monumental contributions and revisions to the pre-existing understanding of the species in a set of newly published papers. With help from her collaborators, whom she accredits for “assisting [her] with data collections, enriching [her] discussions, and moving [her] forward in [her] research”, Lucília discusses the stalked jellyfish’s nomenclatural history, while underscoring an overall need for further analysis and documentation of all things Stauromedusae. Initially compelled by the cnidarian life cycle, Lucília chose to further delve into staurozon biology through an extensive study of stalked jellyfishes for her PhD (part of which was spent as a visiting researcher in the NMNH Department of Invertebrate Zoology), in which she progressively developed interests in areas including the systematics, evolution, and macroecology (the study of the relationships between organisms and their environments) of stalked jellies. With a scarce selection of background information available, the ambiguous nature of such an under-studied species posed obstacles in her research at times, yet Lucília remains grateful for the challenges presented in her work.

Manania uchidai from Hokkaido Japan.

Some of the earliest records of Stauromedusae research (even dating back to more than 100 years ago) contain anecdotal reports of stalked jellyfish populations disappearing from where they were once abundant, possibly due to pollution. Despite such speculations, stalked jellyfishes have never been studied well enough to fully determine how sensitive they are to pollution or other environmental changes, putting them into a precarious position. Who would have thought that simply living off the grid could potentially be so detrimental to a group of species? However, because every species fulfills a unique role in their surrounding ecosystems, identifying anonymous organisms and extracting further information through research initiatives are fundamental steps in piecing together an ultimate understanding of how Earth’s systems sustain life.  

By Meredith Kucik, NMNH Intern

 

Further Reading

Miranda LS, Mills CE, Hirano YM,  Collins AG, & AC Marques. 2017. A review of the global diversity and natural history of stalked jellyfishes (Cnidaria, Staurozoa). Marine Biodiversity. doi:10.1007/s12526-017-0721-4

Westlake H. E., Page L. R. (2016). Muscle and nerve net organization in stalked jellyfish (Medusozoa: Staurozoa). J. Morphol. 278, 29–49. 10.1002/jmor.20617

 

Miranda LS, Branch GM, Collins AG, Hirano YM, AC Marques & CL Griffiths. 2016. Stalked jellyfishes (Cnidaria: Staurozoa) of South Africa, with the description of Calvadosia lewisi sp. nov. Zootaxa 4227 (3): 369–389. doi:10.11646/zootaxa.4227.3.5 

 

Miranda LS, Collins AG, Hirano YM, Mills CE & AC Marques. 2016. Comparative internal anatomy of Staurozoa (Cnidaria), with functional and evolutionary inferences. PeerJ. 4:e2594. doi:10.7717/peerj.2594

 

Miranda LS, Hirano YM, Mills CE, Falconer A, Fenwick D, Marques AC & AG Collins. 2016. Systematics of stalked jellyfishes (Cnidaria: Staurozoa). PeerJ. 4:e1951. doi:10.7717/peerj.1951   

 

Miranda LS & AC Marques. 2016. Hidden impacts of the Samarco mining waste dam collapse to Brazilian marine fauna - an example from the staurozoans (Cnidaria). Biota Neotropica. doi:10.1590/1676-0611-BN-2016-0169

 

Collins AG. 2014. Knowing a body well: On the importance of studying the histology of stalked jellyfish. 

A strange squid appears even stranger IRL

For readers over 30 years old, IRL means "in real life".

Combfin squids in the family Chtenopterygidae are small, muscular, midwater squids that occupy tropical to subtropical waters probably at depths of 500-1000m during the day and near-surface waters at night. The posterior end of the mantle is broadly rounded. The fins are peculiar: they consist of muscular pillars called fin ribs, connected by thin membranes. The membranes are often torn in captured specimens, giving the fin the appearance of a comb; hence the family name. The fin extends nearly the full length of the mantle.

Every time I have caught Chtenopteryx they have been pretty beaten up. A few years ago, when E/V (Exploration Vessel) Nautilus was conducting ROV operations on Thessaloniki Mud Volcano in the Mediterranean, they recorded video of "a small squid" swimming near the ocean floor at about 1300 m. I finally got to see it recently and it was, as far as I know, the first in-situ observation of Chtenopteryx, probably C. sicula. As you can see from the frame grabs on the Tree of Life and the Nautilus Live video below, this strange squid looks even weirder when it is alive. 

When first encountered, chromatophores (tiny pigment sacs) were expanded over the fin ribs, emphasizing these unusual structures. On the dorsal mantle above the digestive gland was a dark oval patch. Also, patterns of chromatophores on the lateral arms are displayed and then fade. The display of these patterns was surprising to cephalopod biologists and the purpose of the displays is unknown. Seeing it near bottom may seem unusual for a midwater squid, but it may just be at the deepest part of its daily vertical migration.

by Mike Vecchione

“GALLERY OF CARCINOLOGISTS” Returns to IZ-NMNH

The Department of Invertebrate Zoology (IZ) holds a unique collection of more than 400 portraits of influential scientists that have worked on crustaceans (carcinologists) from Aristotle to the present. Accompanying the portraits are biographical files that contain valuable information on their life and works. This collection has been painstakingly gathered by various IZ curators, with help of outside colleagues, over many decades, and holds valuable information for biologists and historians of science. The portraits consist of large format photographs and negatives, as well as line drawings (some original), and many were framed and exhibited on the hall walls of IZ, each with a brief biographical summary. This collection exhibited on the halls of IZ floors on the West Wing of the Natural History building was originally called the “Rogue Gallery”.

The biographical files are stored in acid-free reprint boxes and contain original obituaries or copies of biographies, photographs and slides, and in some cases, news clippings and/or unpublished notes on life aspects of the scientists. Given the size and importance of this collection, all components were scanned and digitized over the last decade with the help of several hard working student interns. In a digitized format, this unique resource is accessible to researchers and interested users around the world, and eventually will be posted online.

With downsizing and renovation of the Natural History building (NHB), the “Gallery” exhibit was removed from the walls and moved to for temporary storage at the Museum Support Center (MSC, Suitland, MD).  The portraits were wrapped and packed into storage bins to await their next showing.  Fast forward 4 years (and 2 moves), the “Gallery” once again is up and gracing the walls of the Department of Invertebrate Zoology at NHB. Drs. Rafael Lemaitre and Stephen Cairns were instrumental in making this happen.  Dr. Cairns assisted with selection and placement of the portraits.

A small selection of portraits and corresponding biographies is presented here.

Just a few of the storage bins packed with framed portraits and ready for delivery to NHB.

Selecting and moving Gallery portraits from MSC to NHB. Dr. Cairns holds a portrait of Dr. Paul Illg destined to be hung outside Dr. Jon Norenburg’s office at NHB, by request.

Paul Louis Illg (23 September 1914 – 10 May 1998)

Professor of Zoology, University of Washington. Had an illustrious career in life sciences, and contributed to making his University’s Seattle campus and Friday Harbor Laboratories, one of the leading institutions in the world for studying marine zoology, especially invertebrates. Published prodigiously for more than 50 years on parasitic copepods, particularly those living in ascidians. His research on microscopic ascidicolous copepods greatly extended biological and taxonomic knowledge, and illuminated evolutionary processes in these extremely complex parasitic crustaceans. His work is without equal in the systematics literature.

Arranging the portraits after they arrived back to the halls of IZ at NHB.

First ones first….Dr. Ted Bayer’s portrait was hung outside Dr. Stephen Cairns’ office. (Dr. Cairns was a student of Dr. Bayer.)

 

Frederick “Ted” Merkle Bayer (31 October 1921 – 2 October 2007)

Received his BS from the University of Miami, and MS (1954) and PhD (1958) from George Washington University. Published over 130 papers and books on the taxonomy and natural history of soft corals, describing over 170 new species, 40 genera, and three new families. Species from different groups of animals have been named in his honor, including the hydroid Hydractinia bayeri, described by the Emperor of Japan, Hirohito. A curator at the Smithsonian Institution (1975 until retirement in 1996); emeritus researcher until 2006.

Not a carcinologist, but an outstanding bio-illustrator, he was tasked to create detailed water color sketches of color patterns of live Trapezia, coral reef crabs.  These sketches and associated field notes are now part of the Illustration Archives of the Department of Invertebrate Zoology, and have become extremely useful for modern revisionary taxonomic studies of these spectacular and ecologically important reef crabs.

 

CLASSIC CARCINOLOGISTS:

Georges Cuvier (23 August 1769 – 13 May 1832)   

French anatomist considered the founder of the sciences of comparative anatomy and paleontology. Worked at the Museum of Natural History, Paris. Was Chancellor of the University of Paris, and served in the cabinet of Louis XVIII. An antievolutionist, he became the most eminent European scientist of his time, and virtually an intellectual dictator in the field of biology. Perfected the animal classification system of Linnaeus by grouping related classes into broader groups he called phyla: Vertebrata, Mollusca, Articulata (jointed animals), and Radiata (everything else). In doing so he stressed internal structures as indicative of relationships, rather than external features. Made important collections of crustaceans and published on groups such as the isopods.

Charles Robert Darwin (12 February 1809 – 19 April 1882)

His participation as naturalist in the 5-year voyage of exploration of the H.M.S. “Beagle” (1831-1836) made this expedition the most important in the history of biology. His observations led him to propose in 1858 (jointly with A.R. Wallace) the famous theory of evolution, detailed in “The Origin of Species” (1859). Began work on barnacles in 1846, and intensively studied their larval development, metamorphosis and adult morphology. His 4-volume work on living and fossil barnacles (1851,1852,1854,1855) elucidated their affinities, functional morphology, and evolution, establishing a classification still used today. A painstaking perfectionist in collecting and classifying his information, he was a man of independent means. Member of The Geological Society of London.

Henri Milne Edwards            (23 October 1800 - 29 July 1885)   

Head chair of Crustacea, Arachnida and Insecta, and also of Mammals and Birds, Muséum national d’Histoire naturelle, Paris. Great French morphologist and classifier. Best known for his multi-volume work considered the first breviary of carcinologists: “Histoire naturelle des Crustacés” (1834-1840), where he named 1400 species and 350 genera. First to propose idea that the crustacean body is arranged in series of homologous segments each with a pair of appendages.

Alphonse Milne-Edwards (13 October 1836 - 21 April 1900)        

French carcinologist, succeeded his father (H. Milne Edwards) as chair of Mammals and Birds, and became director of the Muséum national d’Histoire naturelle, Paris. Studied fossil crustaceans, and published many works documenting the diversity and morphology of decapods, mostly Brachyura and Anomura, from classic exploratory expeditions conducted on ships such as the "Travailleur", "Talisman", and the "Blake".

James Dwight Dana (12 February 1813 – 14 April 1895)    

Professor, Yale College. One of the first professional American scientists. Attained the rank of zoologist, then leaving this for geology, his chief field. Became known in 1836 with a treatise on mineralogy, followed by a series of short papers on copepods. Geologist and Zoologist of the “U.S. Exploring Expedition” (1838-1842), one of the great events in the history of science in the United States. In his monumental work “Report on the Crustacea” (1853-1855), described hundreds of new species, and presented a philosophical treatment of the classification, relationships, and distributions of species. Editor for 50 years of “The American Journal of Science”, and founder of the National Academy of Science.

Classic carcinologists: Georges Cuvier, Charles Darwin, Henri Milne Edwards, Alphonse Milne-Edwards, James Dwight Dana.

Modern day carcinologists at the National Museum of Natural History: Austin Beatty Williams, Thomas Elliot Bowman, Isabel C. Pérez Farfante, and Fenner Albert Chace, Jr.

 

SMITHSONIAN INSTITUTION/NMFS STAFF

Austin Beatty Williams (17 October 1919 - 27 October 1999)

Research Scientist, Systematics Laboratory, National Marine Fisheries Service, based at the National Museum of Natural History, Smithsonian Institution. Obtained his Ph.D (1951) at the University of Kansas, studying Ozark crayfishes. His numerous publications covered the taxonomy, systematics, biogeography, and evolution of various decapod groups, both Fossil and Recent. Best known for his invaluable and widely used "Marine decapod crustaceans of the Carolinas" (1965), and its later expanded version "Shrimps, lobsters, and crabs of the Atlantic coast of the eastern United States" (1984). He was co-founder and president (1983-1985) of the Estuarine Research Federation, and was an active member of The Crustacean Society, and the Biological Society of Washington, among others.

(Photo: 1997, taken during ceremony in his honor)

Thomas Elliot Bowman III (21 October 1918 – 10 August 1995)

Curator, Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution. Produced 163 papers on isopods, copepods, amphipods, mysids, and mictaceans. His mastery of crustacean comparative anatomy and morphology led him to produce classic, provocative studies such as on structural homology of the telson and on the evolution of stalked eyes.

Isabel C. Pérez Farfante (24 June 1916 – 20 AUGUST 2009)

Carcinologist Emeritus, U.S. National Marine Fisheries Service, Systematics Laboratory. Born in La Havana, Cuba, she received her Ph.D. from Radcliffe College (1948). She was professor and researcher at the University of Havana; director of the Cuban Centro de Investigaciones Pesqueras; and associate in Invertebrate Zoology, Museum of Comparative Zoology, Harvard University. She has authored zoology textbooks, and numerous papers on the systematics of penaeoid shrimps, most notably landmark studies of the commercial genus Penaeus. She is senior author of the book “Penaeoid and sergestoid shrimps and prawns of the world” (1997). (Married name: Isabel C. Canet)

Fenner Albert Chace, Jr. (5 October 1908 – 30 May 2004)

Zoologist Emeritus, National Museum of Natural History, Smithsonian Institution. Born in Fall River, Massachusetts. Obtained his Ph.D. in 1934 from Harvard University. He was Assistant Curator of Invertebrates (1934-1942) and Curator of Crustacea (1942-1046), at the Museum of Comparative Zoology, Harvard University. Joined the staff of the U.S. National Museum* in 1946 where he worked until his retirement in 1978. He then completed his 7-part study of the caridean shrimps from the “Albatross” Philippines expeditions (1907-1910), published in Smithsonian Contributions to Zoology between 1983 and 1997. His interests centered primarily on caridean shrimps, and he is considered by his peers as one of the most influential and respected specialists on caridean shrimps in the latter half of the 20^th century.

Mary Jane Rathbun (11 June 1860 – 14 April 1943)

Ascended from “copyist” to assistant curator in charge of the Department of Marine Invertebrates, U.S. National Museum. Prodigiously productive, considerably advanced knowledge of fossil and Recent decapod crustaceans of the world, describing 1147 new species, 63 genera, and 5 higher categories. Best known for her unparalleled, monumental 4-volume monograph of New World brachyuran crabs, and a treatise on freshwater crabs.

Waldo LaSalle Schmitt (25 June 1887 - 5 August 1977)

Head curator, Department of Zoology, U.S. National Museum. Succeeded M.J. Rathbun. His tireless collecting efforts during numerous expeditions worldwide led to the immense holdings of the national collections. His dedication to the advancement of invertebrate systematic zoology contributed to the unmatched growth and international recognition of the Department. Author of numerous taxonomic studies on decapods and stomatopods, and the popular book "Crustaceans" (1^st printed 1931).

Raymond Brendan Manning           (11 October 1934 – 18 January 2000)

Senior Zoologist, Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D.C.  Earned his BS (1956), MS (1959), and PhD (1963) from the University of Miami.  He published 278 papers on stomatopods and decapods, including landmark monographs and other studies on West African crabs, Indo-pacific dorippids, commercial geryonids, cave shrimps, and callianassids.  Above all, he was a master in stomatopods, and increased the known species from a handful to nearly 500 worldwide.  In all, he named 279 species, 138 genera, 5 subfamilies, 19 families, and 3 superfamilies of extant decapods and stomatopods, and at least 15 genera and 27 species of fossil decapods.  A tireless collector, he obtained more than 50,000 decapod and stomatopods for the Museum and other institutions.  One of the founders, and first President (1981-1983) of The Crustacean Society, from which he received in 1999 the “Excellence in Research Award”.

 

OTHER NOTABLE CARCINOLOGISTS:

Aristotle (384 – 322 B.C.)

Greek philosopher, founder of zoology and natural history. Organisms we now call crustaceans (decapods, stomatopods, copepods) can be identified in his “Historia Animalium” under the account of “bloodless” animals. His description of 180 different Aegean Sea animals is the precursor of all subsequent publications in marine biology.

Maria Sibylla Merian (12 April 1647 – 13 January 1717)

Artist-naturalist, born in the imperial city of Frankfurt am Main. She was not only skilled in watercolor and oils, but also was a keen observer of habits of caterpillars, flies, spiders, and other creatures. Her most famous works are her “Raupen”, and after traveling to America, her “Metamorphosis of the Insects of Suriname”, and “European Insects”, which include exquisite plates depicting life stages of insects.  She can be hailed as the first woman carcinologist as she prepared 60 crustacean paintings for Georg Everard Rumpf’s (Rumphius) 1705 book on the crustaceans from Amboina.

Jean-Baptiste P.A. de Monet de Lamarck (1 August 1744 – 28 December 1829)

French naturalist. Took a long time finding himself. As a soldier he fought with distinction in the Seven Years’ War. In 1781 he was appointed botanist to the king, and in 1793 (at nearly 50 years of age) professor of zoology at the Museum of Natural History in Paris, at which time he came into his own. Between 1815 and 1822 he produced the gigantic 7-volume work “Histoire naturelle des animaux sans vertèbres” which founded modern zoology. He coined the terms “vertebrate”, “invertebrate”, and “biology”. In his book “Philosophie Zoologique” he was the first biologist of rank to rationalize the evolutionary development of life. Unappreciated and often maligned in his time, he died blind and penniless.

Constantine Samuel Rafinesque (22 October 1783 – 18 September 1840)    

Born in Constantinople, Turkey, into a French-German family. He privately studied natural sciences, medicine and mapmaking. He was an eccentric, perhaps unbalanced man, but his intellectual breadth was enormous. A keen naturalist, nearly every one of his 900+ publications is rare, appearing in obscure places or journals. His carcinological work focused on the faunas of Sicily and the eastern U.S. Most of the numerous crustacean names he proposed never attained taxonomic status because of faulty descriptions, lack of illustrations, and his practice of not keeping specimens. His work was unfairly ignored or minimized by contemporaries. He died in poverty and isolation in Philadelphia, and his collections and books sold as junk. In early years he used the name Rafinesque-Schmaltz.

by Rose Gulledge

 

Visiting PhD Student Investigating Parasites of Mammals

I am a little hesitant to tell people outside of my research field what I study, which is surprising if you know me - I love talking about my research. It’s fascinating (and I’m not at all biased). I would like to think my enthusiasm for my research project is contagious; however, my fervor is often met with varying degrees of disgust. Why?

Because I study parasites. And not just any parasites; I study the roundworms, tapeworms, and flukes of rats and mice. Not only is there a stigma against parasites, but also against the rodents I collect. I will spare you the explanation of why rodents are awesome and mostly misunderstood, but I will be delving a bit more into the study of parasites.

These groups of parasites, the roundworms, tapeworms, and flukes, are collectively known as helminths. In most cases, these helminths reside in the body cavity, organs, and various tissues of their hosts. While their creepy crawly nature may repulse some people, they are remarkably important to individual hosts, populations, communities, and to the ecosystem as a whole, yet they are often ignored in many fields of study in the biological sciences. There is a growing body of literature attesting to their importance even outside of human and veterinary medicine (see citations below for a few examples).

Whitney working at the microscope picking worms.

 

Before scientists can determine the role of parasites in host evolution, community ecology, trophic ecology, and so on, we must first know more about parasite diversity and abundance. Parasites are largely understudied, and species new to science are still being discovered and described. Parasitological surveys of hosts have merit for documenting the diversity and abundance of parasitic species in hosts.

I approached Dr. Anna Phillips at the American Society of Parasitologists’ annual meeting in July 2015 about joining one of her research projects. Anna, a research zoologist and one of the curators of the invertebrate collections, is collaborating with researchers in Spain to investigate the parasite fauna of rodents and tree shrews from Borneo. Few studies have examined the parasites of these species from these localities, so this investigation is important to determine the diversity and abundance of the parasites of these hosts.

We have a few goals for this research. First, we will document the helminth diversity and abundance in these hosts. Second, we will describe species new to science. This will allow for these helminth species to be included in future ecological and evolutionary studies and considered in conservation management plans. Third, these helminths will be DNA barcoded – certain genes will be sequenced and input into an open access database for future use by other scientists (for example, for identification or phylogenetic studies).

This past May, I spent three weeks going through some of the rodent specimens looking for parasites. Unfortunately, I was only able to get through a small portion of the rodent samples – fortunately, this was due to the high numbers of parasites found in each specimen. Morphological and molecular identification for these first samples is ongoing; we hope to have the rest of the parasites collected and identified by next year. After identification, the parasite specimens will be deposited into the National Parasite Collection for future scientific use.

With such a large number of helminths found in the intestines of each rodent, you may wonder if the rodents and tree shrews were alive when they were collected. Yes, they were alive! So were they sick?

That is a more interesting question. Parasites can affect their hosts in a variety of ways – they can influence host reproduction, behavior, health, and life span. The effects and their magnitude differ between parasite species and host species, and are influenced by the number of parasite species and the number of individual parasites infecting the host.

Back to the original question – what about the rodents and tree shrews? I did not collect these specific rodents and tree shrews so I don’t know if they were lethargic, skinny, weak, acting strangely, in breeding condition, etc. We do have some clues about the parasites’ effects on their host’s health though. I examined the organs where the parasites were located, and in most cases, I only found slight physical damage, often to the intestinal villi. There were some specimens with more serious damage: intussusceptions, where a portion of the intestine inverts itself, and multiple perforations of the intestinal and stomach wall were present.

Intussusceptions in humans and other animals can cause abdominal pain, vomiting, and diarrhea. While this condition has been linked to infection with parasites, there are other causes too. There is no way for us to definitively say that these intussusceptions were results of parasitic infection. If they were linked, we would be able to conclude that these parasites are having a negative impact on their hosts’ health.

We can conclude that the perforations of the organ walls were caused by the parasites. I found a number of nematodes half buried in the walls of the stomach and the large intestine. I did not find any of the worms passing completely through the organ wall; rather, the walls were thickened where the parasites had burrowed in. The hosts likely suffered abdominal pain when the worms originally burrowed into the organ walls, and may have also experienced blood in the feces or diarrhea.

Roundworms embedded in the wall of a mammal’s stomach.

With parasitological studies such as this one, we are limited to making observations and finding correlations between a parasite’s presence and possible effects on the host. Experimental and manipulative studies are required to definitively link cause and effect, but observational studies are still very important for determining the biodiversity and abundance of parasites, as well as driving the formation of hypotheses linking parasites and their effects on the host.

In the next few months, we will continue to sort through the rodent and tree shrew specimens, collecting, sorting, and counting the helminths found. Helminth specimens will be sequenced for DNA barcoding, prepared for museum installation, and described as a new species if they are species new to science. We look forward to the exciting discoveries and results from this work!

By Whitney Preisser, a fourth year doctoral student in the Department of Wildlife and Fisheries Sciences at Texas A&M University. Her research investigates the latitudinal diversity gradient of parasitic helminths in North America. She can be reached at wpreisse *at* tamu.edu.

Further Reading

1. Altizer, S, CL Nunn, and P Lindenfors. 2007. Do threatened hosts have fewer parasites? A comparative study in primates. Journal of Animal Ecology. 76:304-314.
2. Fenton, A and MA Brockhurst. 2008. The role of specialist parasites in structuring host communities. Ecology Research. 23:795-804.
3. Palm, HW, S Kleinertz, and S Rückert. 2011. Parasite diversity as an indicator of environmental change? An example from tropical grouper (Epinephelus fuscoguttatus) mariculture in Indonesia. Parasitology. 138:1793-1803.
4. Ricklefs, RE. 2015. Intrinsic dynamics of the regional community. Ecology Letters. 18:497-503.
5. Wood, CL, JE Byers, KL Cottingham, I Altman, MJ Donahue, and AMH Blakeslee. 2007. Parasites alter community structure. Proceedings of the National Academy of Sciences of the United States of America. 104:9335-9339.
6. Dougherty, ER, CJ Carlson, VM Bueno, KR Burgio, CA Cizauskas, DP Seidel, NC Harris. 2016. Paradigms for parasite conservation. Conservation Biology. 4:724-733.