Liggers, snails and the Everglades

 

Among the most beautiful snails are the Florida Tree Snails of the genus Liguus. Few groups of molluscs have such a storied past. Liguus, or Ligs, are arboreal snails occurring in southern Florida, Cuba, with a single species in western-most Haiti. The number of species involved depends on the people asked and the amount of beer consumed. Most people agree that Cuba, with an abundance of named species, was the ancestral home of the group. It was probably only a short hop for Guantánamo’s snails to the Haitian shore via hurricane-driven foliage. And many, including this writer, believe that Ligs were also the original Cuban refugees to Florida – rafted from Cuba to the Keys and the Gold Coast. And from there, all heck broke loose.

Delicatus form

Delicatus form

The situation is this: the snails live in hammocks, which are islands of trees surrounded by sawgrass and other soggy vegetation. To the tree-hugging snails this intervening area might as well be the ocean. They cannot, by themselves, get from Hammock A to Hammock B unless they are blown there on vegetation during hurricanes or perhaps rafted during floods. It is what happens next that is important. In all likelihood only a very few snails will make it to the next hammock. Should they survive and there are enough individuals to mate (they are hermaphrodites) or they are already pregnant, that next generation, now isolated, will have only a small fraction of the genetic variation of the original populations. The result is an enormous variety in shell coloration where specific patterns only occur in a single hammock or group of hammocks. Fifty-nine patterns have been named.

 

Barbouri form

Barbouri form

In Florida the Ligs occurred in three general areas: the Keys, the Gold Coast, and the Everglades. Collecting them, particularly in the Everglades, could be an adventure. And those adventurers called themselves Liggers. On foot, on horseback, in Model As, some of America’s most famous malacologists ventured into the chigger-infested, cotton-mouth crawling, gater guarded, sawgrass cutting landscape in the early 1900s. Long before GPS or even decent maps, these intrepid collectors produced hand-drawn maps and named and numbered hundreds of hammocks and cataloged the Ligs they found there. Archie Jones, perhaps the most experienced of the Liggers, once remarked that a Ligger needed two qualities: high stamina and low IQ.

 

 

Lignumvitae form

Lignumvitae form

These were not just shell collectors. They were conservationists. They quickly realized that many of the hammocks were being destroyed and others would inevitably be lost as well. The Keys were being cut-over for houses. The Gold Coast was being paved in concrete for posh hotels. The hammocks, and their unique snails, would soon be lost forever. But by 1957 snails were being transplanted out of harm’s way into the newly formed Everglades National Park where they would be protected. Most of the 59 “forms” still exist today but perhaps not in their original location. That’s where the Division of Molluscs comes into the picture.

 

 

We have one of the largest collections of Florida Liguus in the world, much of it purchased directly from Archie Jones. We were interested in zoogeographic patterns between the color forms. We used the powerful but complicated mapping software ArcIMS to plot the various distributions. But first we had to georeference the hundreds of Liguus hammocks – whose location you may remember was in the form of hand-drawn maps nearly a hundred years old. With the invaluable aid of several students we found and plotted the hammocks. Using a layer for each color form it was possible to compare distributions with each other and other environmental factors such as land type. The effort is available on line through our Division website. It is the first of its kind to map these snails (and the only one as far as I know). Go here and select “Maps:”

http://www.biosci.ohio-state.edu/~molluscs/OSUM2/

Septentrionalis form

Septentrionalis form

Original range

Original range

Original range under concrete

Original range under concrete

Castaneozonatus form

Castaneozonatus form

Original range

Original range

Besides being beautiful shells the Ligs beg several very interesting ecological and phylogenetic questions. The elephant in the malacological room is: “Are they all the same species, just local variations, the product of a single Cuban introduction?” I suspect not. My pet hypothesis, lacking any data whatsoever, is that our Floridian Ligs are the product of several introductions of several species. “Are they color forms, species, subspecies, or something else?” I suspect something else. I think this is a fantastic opportunity for some student to investigate this complicated problem using emerging phylogenetic methods.

As a parting word, the Olde Tyme Liggers were not averse to a little ad hoc experimentation. “I wonder what would happen if we took this snail from Hammock A and this snail from Hammock B and put them in a snail-less Hammock C? Whaddaya think?” Well, they form hybrid color patterns, all dutifully named after colleagues and wives.

About the Author: Dr. G. Thomas Watters is Curator of Molluscs at the Museum of Biological Diversity.

You’re an insect curator. Cool! So what is it you do?!

 

We frequently give tours of the Triplehorn Insect Collection to school groups, families, etc.  Since most entomologists like to talk about their insects, that’s usually a fun time for me.  It is also a great time to flex my General Entomology muscles.  Visitors ask lots of questions, some of them interesting (How many ants are there in an ant’s nest? Do young cicadas sing underground?), some funny (Do you eat bugs every day?), some actually very difficult to answer (How many bugs are there in the world right now, how much do they weigh, and how do you know? How come you don’t have a list of all insect species in the world?).

Open collection cabinet showing insect drawers.

Open collection cabinet showing insect drawers.

During a recent tour of the collection, after my brief intro on the history and structure of the collection, an 8-year old visitor asked me point blank: ‘If all the bugs in the collection are dead & put away in their little boxes, what do you do the whole day?’  Somebody behind me gasped, but I thought that was a good question, especially as I had just told them that we keep our specimens in cabinets, safe from humidity, light, and especially other bugs that might want to try and eat the dead specimens. So I told them that, yes, we keep the insects safe in cabinets, but that’s when they are not being used. And use them we do, a lot!

Much of what we know about the natural world comes from museum specimens. Scientists use the specimens and the data associated with them to answer many basic questions such as:

  • Where can you find this (species of) wasp? – museum specimens have labels attached to them that contain locality information.  The geographic coordinates for the locality can be plotted on a map like the one below. Data for multiple specimens of a species help us understand the geographic distribution of the species.

    Distribution of Pelecinus polyturator based on museum specimen data.

    Specimen records plotted on a map show the skewed distribution of Pelecinus polyturator, a parasitoid wasp, in North America.

  • When is the best time of the year to find that wasp? – specimen labels may contain a date of collection, which then may help pin-point the time of the year the species can be found in a specific place.
A detailed specimen label.

This label provides both detailed locality data and biological information (host species) as well.

Detailed specimen labels.

Label including geographic coordinates, altitude, type of trap, and habitat.

With locality and date of collection alone we can already learn a tremendous amount about that species of wasp.  For some areas, we can look up weather reports from that exact day and see if it was raining that day, what the average, the maximum and minimum temperatures were, also the barometric pressure, and other environmental factors that may (or may not) affect the species.

Labels may provide information on the way the specimen was collected (examples: by hand at light; using traps like a Malaise (below, middle), or yellow pans (below, right)), and the kind of vegetation (forest, grassland, prairie, etc.) encountered in the area it was collected.

Light trap

Malaise trapYellow pan trap

 

 

 

 

Sometimes labels also include information on what the specimen was feeding on, burrowing in, coming out of, what other species it was associated with, and more. It is quite amazing how much valuable information insect collectors manage to squeeze onto a tiny piece of paper!

The label information found on museum specimens is extremely valuable data for scientists trying to learn about a species and to start assessing the impact of environmental changes on living organisms.

Now, back to the young visitor’s question: ‘What do we do the whole day?’ One of the major responsibilities of a curator (= caretaker) is to make specimens and specimen data available for scientific study. That can be done either by carefully packaging and sending the specimens on loan to a scientist, or, more recently, by databasing the specimen information and making it available online to the scientific community and the general public.  Either way, that involves a lot of work, particularly in a large — we hold about 4 million dry specimens — and, relatively old — we just turned 80 in 2014 — collection like the Triplehorn.  It is not uncommon for us to loan 3,000 specimens to one scientist. The largest loan we sent out to date contained 28,000 specimens – we worked on the preparation of that loan for months!  We also welcome scientists who want to come on research visits to the collection.

So, just making the specimens and the specimen data available to the scientists is a lot of work. We could stop right there and we would still be very busy every day of the week. But we don’t stop there, oh no!  The collection keeps growing in various ways.

  • Scientists deposit voucher specimens of their research with us — that’s actually one of our main missions, to house and preserve vouchers of scientific studies so other scientists can examine those specimens if and when they need to.
  • Private insect collectors also donate their collections to us — just last month we were presented with the late Steve Sommer Collection of butterflies and moths from Ohio and the Midwest, about 1,000 specimens.
Repairing specimens.

Repairing specimens.

These new arrivals are placed in a -40°C freezer for several days to kill any potential pests that might be infesting the specimens.  Next they are examined for damage, and even sometimes fixed — broken parts are glued to a card or put away into tiny vials or gel caps. After this basic upkeep work is done, we add the specimen data into our database — sounds simple, but there are many steps to that operation, and, you guessed, a lot of work involved. Finally, we add the specimens to the main collection.

I won’t get into details of the curatorial or the databasing work here, but in case you are interested, you can read about it in the collection’s blog, the Pinning Block, and follow our  posts on our Facebook page.

Oh, and did I mention we collect?  Yes, we collect new specimens for our own research (in my case, and Dr. Johnson’s, it is parasitoid wasps), or to fill in the gaps we have in the collection. That’s a big source of growth and (guessed righ again?) more work!

Dr. Norman Johnson collecting parasitoid wasps in South Africa.

Dr. Norman Johnson, Director of the Triplehorn Insect Collection, collecting parasitoid wasps in South Africa.

Newly collected specimens are always being prepared, dried, mounted, labeled, databased, and added to the collection.  These specimens will one day be studied by scientists and maybe even be described into a new species.  In the meantime it is up to the curatorial staff of the collection to keep them safe and accessible. And that’s an entirely new post. Keep tuned!

About the Author: Dr. Luciana Musetti is the Curator of the Triplehorn Insect Collection at Ohio State University. All photos are courtesy of the author.

Thanks to Norman Johnson & Gisele de Souza da Silva for careful review and thoughtful suggestions.