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Carnegie Museum of Natural History is home to active research and vast scientific collections. Our scientific researchers regularly contribute to the blog at the museum.

September 14, 2020 by carnegiemnh

Overwintering for Amphibians and Reptiles

by Amanda Martin

With Autumn upon us, temperatures are dropping, and it is getting colder out. Especially in the northern regions, amphibians and reptiles need to prepare for brumation (essentially, hibernation for ectotherms). Ectotherms like frogs, salamanders, snakes, and turtles are highly sensitive to changes in their environment and need to stay warm by actively moving in and out of areas with heat. When temperatures increase, ectotherm metabolism increases, and when temperatures go down, so does their metabolism. But how do they survive during winter, won’t they freeze?

Fig. 1. Eastern garter snake. Photo by A.K. Martin.

Many snakes, like eastern garter snakes (Fig. 1) find shelters called hibernacula and curl up inside, sometimes intermixed with other snake species. These hibernacula are often small mammal burrows, dens, or tunnels below the frost line. During winter, typically between October and March, several hundred individuals will gather in the same den, tightly coiling their bodies together to stay warm enough to survive. They stop eating during this period because it is too cold to properly digest food and will stay hydrated by absorbing moisture through their scaly skin. Even though snakes are awake and sluggishly active, they expend very little energy during this time and do not lose much weight.

Fig. 2. Eastern box turtle. Photo by A.K. Martin.

Turtles, on the other hand, are a bit different. Aquatic turtles survive winter underwater, and the terrestrial eastern box turtle (Fig. 2) buries itself underground by digging into the soil. One extreme overwintering survivor is the painted turtle, which spends most of its time in ponds and slow-moving freshwater. When these ponds freeze, painted turtles bury themselves up to 45 cm (nearly 18 inches) in mud beneath the pond’s surface. Amazingly, these turtles can survive for months in low or no oxygen environments. During warmer months, they breathe air, but when submerged for overwintering they absorb oxygen through the thin skin of their cloaca, a phenomenon called cloacal respiration.

Fig. 3. Wood frog. Photo by A.K. Martin.

Another amazing overwintering feat is the freeze tolerance of wood frogs (Fig. 3) which can become frogsicles! Wood frogs are unable to bury themselves completely, like turtles, so part of their body is often exposed when trying to stay underneath the mud. This is beneficial for obtaining oxygen through their skin. However, they still need to avoid freezing and will move around to warmer areas as needed. Many frogs stay in burrows or under leaf litter to escape the frost, but wood frogs will stay at shallower depths because they have high concentrations of glucose, which produces an “antifreeze” effect. This protects their organs when over two-thirds of their body freezes!

Fig. 4. Red-backed Salamander. Photo by A.K. Martin.

Other amphibians, like salamanders, do not have freeze tolerance like the wood frog. Red-backed salamanders (Fig. 4) are one of the most abundant species in the eastern United States. They are typically found underneath logs and leaf litter at shallow depths, but during winter when temperatures drop below 30°F, they travel as much as 15 inches under the ground in animal burrows. Other species, like spotted salamanders, will also look for deep burrows that are below the frost line.

In early spring when temperatures warm, amphibians and reptiles emerge from overwintering to look for basking sites, sunny spots to warm themselves. With warmer temperatures, the prey of many of these species also become more available. Garter snakes will look for slugs, earthworms, amphibians, minnows, and rodents, for example, and red-backed salamanders will eat a wide variety of invertebrates, such as spiders, worms, snails, and insects. The exact timing of emergence for amphibians and reptiles depends on a given year’s weather, resulting in variable emergence times from year to year that correspond to temperature. Not every individual makes it to the spring, but it is amazing that species that are so dependent on the temperature of their environment are capable of surviving up north!

Written by Amanda Martin, Post-doctoral Researcher in the Section of Amphibians and Reptiles at Carnegie Museum of Natural History. Edited by Jennifer Sheridan, Assistant Curator in the Section of Amphibians and Reptiles at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

Feeding the Monster in the Sewer

Water is a resource that I often take for granted. I take daily showers, wash my dishes, and do my laundry without a second thought to the amount or quality of water that is used. I only experience small aspects of the natural water cycle on a daily basis, from a bit of condensation on a cold glass of water to the sporadic downfall of rain that occurs in Pittsburgh. The water cycle that I’ve learned about in school can be boiled down to: precipitation, surface runoff, infiltration, evaporation, and condensation; but how do I, as a human being, fit into all of this? What is the human water cycle and how have parts of the water cycle changed within the Anthropocene?

drawing of the city water cycle from waste water to drinking water

As intrigued as I was, I didn’t know enough about my own impact on the water cycle, so I took a deeper dive into learning about what was actually happening to the water that I used. In order to explore the concept of the human water cycle I needed to start by looking at infrastructure. In the case of water infrastructure, outside of irrigation, the water purification systems and sewage systems are some of the most impactful additions human beings have included into the planet’s water cycle. These infrastructural systems span thousands and thousands of miles underground, connecting houses, neighborhoods, and cities. And yet, at least for me, there was a vast mental disconnect between the water that flows underneath us and the water that we consume. I wasn’t sure how to visualize something that was happening underground, hidden away from sight. That’s when I learned about fatbergs.

In 2017 an 820 foot long mass weighing 130 metric tons was discovered in the sewers of Whitechapel in London, England. The same type of mass, weighing 42 metric tons was found in Melbourne, Australia during the outbreak of the COVID-19 virus, most likely due to the flushing of “toilet paper substitutes” (i.e. paper towels, sanitary products, facial tissues). These masses are called fatbergs and can be found in most major cities, especially those with older sewage systems like Pittsburgh. A fatberg is a solidified mass of fat, formed overtime in sewers, that sticks to the build-up of un-flushable sewage. Fatbergs cost hundreds of thousands of dollars to remove, and also reduce river and stream water quality by making sewer overflows more likely. In the Pittsburgh Area, whenever the combined storm and sanitary sewer system is overloaded, excess flow is dumped directly into the rivers.

drawing of a pipe with a fatberg forming in it

Fatbergs are a human phenomenon that directly impacts both us and the greater environment. The sewer overflows that they cause impact both the built and natural environment, introducing pollutants such as human waste from our toilets and fats from our kitchen sinks into the living domain. But as harmful as they are, they can be easily prevented.

How, you ask? The solution is simple… don’t flush down anything other than toilet paper and bodily waste. But why? What makes toilet paper any different from other paper-like materials? The answer lies in the unique quality of the material that toilet paper is made up of. Unlike paper towels that use long fiber pulps, which improves the strength and absorptivity of the material, and facial tissues that contain additives that hold the fibers together, toilet paper is made using approximately 70% hardwood pulps with short fibers and 30% softwood pulps with longer fibers. Due to the hardwood pulps, once the toilet paper makes contact with water, the short fibers, which also help keep the toilet paper soft to touch, are able to untangle and fall away into smaller fragments, eventually dissolving into tiny bundles of short fiber that can easily flow through the sewage system.

jar, wet paper, and a drawing of paper fibers

Objects like ‘flushable wipes’, unlike toilet paper, take hours to days to break down. This means that just because we are able to flush something down, doesn’t necessarily make it safe for sewer and septic systems. If you want to try an experiment to explore this concept, try putting ‘flushable’ wipes and toilet paper into two separate containers of water. See for yourself what happens.

Fatbergs are all the more relevant to us during the times of the pandemic, especially in the United States. As people stay home, more objects that aren’t healthy for the sewage system are being flushed. Think about the times you flushed anything other than toilet paper. Are you feeding a potential fatberg in your neighborhood?

Daniel Noh is an intern for the Center for Anthropocene Studies, Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

Snails in the Desert

Land snails are leaky bags of water that survive on dry land. Snails lose water through evaporation, and because mucus is more than 90% water, they must expend water just to move, gliding on their silvery slime trails. Most land snails occur in moist environments where they can readily replenish lost water. But some snails live in the desert or other arid areas! How is that even possible?

Several strategies help snails survive in arid situations. For example, some close their aperture with a door or with a mucus sheet, some have small apertures or modify their growth direction to make better seals, some have mucus that inhibits evaporation, and some manage moisture loss by choice of microhabitats.

Fig. 1. Two *Clydonopoma poloense* snails from Dominican Republic showing their opercula. (Photo by S.P. Aiken with permission.)

An operculum, or door, closes the shell in some land snails (Fig. 1), although most land snails lack one. The operculum is attached to the rear of the snail’s tail; when the snail pulls into its shell, the tail withdraws last and positions the operculum to make a tight seal. In addition to protecting the snail from water loss, it also protects from predators.

Fig. 2. Two *Helix pomatia* edible snails from Russia (CM154077) with apertures closed by an opaque epiphragm. (Photo by T.A. Pearce.)

Snails that don’t have an operculum can cover the aperture with a mucus sheet called an epiphragm. In most snails, the epiphragm is thin and clear, but in some species, the epiphragm can be thick and opaque (Fig. 2). During dry periods, snails can form an epiphragm over the aperture or they can make a tight mucus seal between the aperture edges and substrates such as a rock or plant. The seal helps to retard evaporative water loss. Some snails in the desert remain sealed under a rock for years before a rainstorm wakes them.

Fig. 3. *Coelocentrum gigas* from Guatemala CM62.8574 (left); *Achatina zebra* from Africa CM62.6917 (right). Land snails in drier areas tend to have relatively smaller apertures like the shell on the left. Shells pictured are 8 and 8.5 cm tall, respectively. (Photo by T.A. Pearce.)

Snails of arid areas usually have a relatively small aperture (Fig. 3). The smaller surface-area-to-volume ratio reduces moisture loss through evaporation. Just like you would lose less heat (on a cold day) with your parka zipped up and your hood cinched around your face, the snail loses less water with less of its skin exposed, as in the case of a smaller aperture.

Fig. 4. *Ganesella fusca* (left) from Japan (CM106167) and *Zachrysia guanensis* (right) from Cuba (CM152889). Land snails in drier areas tend to have greater change in direction of growth when reaching full size, allowing the plane of the aperture to make a closer seal with flat surfaces. (Photo by T.A. Pearce.)

As growing snails approach their final size, many dip the direction of shell growth toward the shell base (Fig. 4). This results in the plane of the aperture making a tighter seal on a flat surface. Snails of arid areas tend to have shells that make tighter seals on flat surfaces than snails of moister areas.

Fig. 5. Urocyclid semi-slug from a dry area in N Kenya. (Photo by T.A. Pearce.)

The mucus of some species retards evaporation. Snails produce different kinds of mucus, for example, the mucus they glide upon to move, sticky or distasteful mucus when irritated, and mucus on their skin that can retard evaporation. One day when I was traveling in northern Kenya during the dry season after at least 6 months without rain, I was surprised to find a semi-slug (a gastropod whose shell is too small to fit the entire body) resting among some dry leaves and soil (Fig 5). It must have had special mucus covering the body that retarded water loss, allowing this species to survive many months of aridity.

Finally, snails influence their moisture loss by choosing their microhabitats. Some snails burrow underground during hot, dry weather to escape the heat. Other snails crawl under moist logs or descend deep into rock piles to avoid the harshest weather.

Why would snails even choose to live in the desert? I’m not sure anyone knows the answer for sure. My guess is that snails might live in a desert because it allows them to escape predators or competitors who can’t or don’t want to live there.

How do they do it? Snails survive in the desert by leaking water a bit more slowly than snails in moist areas.

Timothy A. Pearce, PhD, is the head of the mollusks section at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

From the Allegheny to our Kitchen Sinks

There are more than 326 million trillion gallons of water on our planet. Our bodies are made up of around 60% water. Even the air that we breathe has water vapors in it. Water is everywhere, but the water we can use is limited. According to the National Groundwater Association, the Earth is made up of about 71% water. Out of that, 99.7% is trapped in oceans, icecaps, soil, and the atmosphere. That leaves us with around 0.3% of the Earth’s water to use and drink. The same water that all living and nonliving things have used again and again since water has been on the planet.

Every morning I go downstairs to the kitchen and pour myself a glass of cold water from a water filter. Without a second thought, I drink the water because I consider this water to be safe. After all, the porous, activated carbon filters absorb various chemicals, including chlorine, lead, and mercury, which ‘purifies’ the water. Furthermore, I don’t have to worry about what could be in the water, because I know that the water is thoroughly cleaned before it enters the house. But how is it cleaned? Where does this water come from and what does it go through in order to splash into my kitchen sink?

Let’s start with a broader concept: rivers. Most major cities can be found along rivers: Paris along the Seine River, London along the River Thames, Seoul along the Han River, and New York along the Hudson River. This is no surprise, as communities need fresh, drinking water as an essential part of building a city. Pittsburgh is no different. In fact, in Pittsburgh, two rivers, the Monongahela and the Allegheny form a third, the Ohio, which on its passage through Pennsylvania, West Virginia, Ohio, Kentucky, Indiana, and Illinois, is the primary water source for over five million people. Within the city, the Allegheny River provides us, the people of Pittsburgh, with fresh water that we use on a daily basis.

illustration of the water cycle: condensation, precipitation, runoff, evaporation

If my water comes from the Allegheny River, what’s the difference between drinking tap water and river water? That’s where the Pittsburgh Water and Sewer Authority, or the PWSA, enters the picture. PWSA is the organization in charge of providing quality water throughout the city of Pittsburgh. The organization’s drinking water system “contains approximately 965 miles of water lines, five reservoirs, and 11 tanks with a water storage capacity of 455 million gallons” (pgh2o.com). And their process for making clean water looks like this. First, the collected river water is coagulated using ferric chloride, potassium permanganate, carbon, and catatonic polymer, which react to the polluting particles in the water, causing them to stick and clump together. The water is then taken through the filtration process, where it flows through pulverized anthracite coal and sand to remove any of the remaining particles. Afterwards, the water is disinfected with sodium hypochlorite, a type of chlorine compound that is used to remove microbial particles. Lastly, once the water has been completely purified, fluoride, the processed form of a naturally occurring mineral, is added back into the water as recommended by the Center for Disease Control to prevent tooth decay.

image of sewage treatment and water treatment over water cycle

As complex as this purification process is, it isn’t perfect. The quality of the water that we receive is affected by what we put into it and there are countless compounds that cannot be completely filtered out by the processes used in water treatment plants. For example, trace amounts of dioxane, a likely human carcinogen from plastic manufacturing runoff, can be found in Pittsburgh’s own water system. Moreover, as of 2019, the PWSA has introduced orthophosphate in order to reduce lead levels, originating from the city’s ancient water pipes, in our tap water. In the end, all the water treatment plants can do is clean the water, test for contaminants, and research new ways to produce and deliver as clean a product as possible. The rest is up to us, the community. It’s up to us to be cautious of how we treat water by watching what we flush, preventing littering, or even reducing plastic use to reduce both microplastics and plastic production.

Water treatment is a growing process; new methods to remove previously unfilterable chemicals are constantly being discovered. With this in mind, think about your relationship with water. How do you treat it? What kind of objects do you flush down the toilet? What are your direct and indirect interactions with our water system? All of our actions matter. Because what we put into the river, will eventually come back to us.

Resources

https://blogs.scientificamerican.com/guest-blog/the-purest-of-them-all/

https://www.portpitt.com/pages/monongahela-river

https://www.wpxi.com/news/what-you-need-to-know-about-pittsburghs-three-rivers/739536503/

http://www.orsanco.org/river-facts/

https://coolcosmos.ipac.caltech.edu/ask/67-How-much-water-does-Earth-have-#:~:text=There%20are%20more%20than%20326,in%20ice%20caps%20and%20glaciers

Canada Goose

When I think of September and waterfowl, my first thoughts go to the Canada Goose (notice I did not say Canadian Goose which is actually an incorrect name of the bird – there are of course “Canadian Canada Geese”). Nevertheless, my thoughts go to the “American Canada Goose” which seems to be everywhere near water come early fall, and the sounds of them honking puts a little flutter in those Pennsylvanians who hunt. September 1 was the first day of the resident Goose season which runs through September 25^th.

Eighty years ago, Canada Geese almost never spent the summer in Pennsylvania. W.E. Clyde Todd, the first curator in the Section of Birds at the Carnegie Museum, kept meticulous records of the comings and goings of many birds in Western Pennsylvania. He has the distinction of the longest tenure of any employee at the museum, having started as a field collector in 1898 and retired and became emeritus curator in 1944. Even after retiring, he continued to come to the museum almost daily until his death in 1969. Mr. Todd, who lived most of his life in Beaver, published the landmark book Birds of Western Pennsylvania in 1940. Several paragraphs in the chapter on the Canada Goose mention early arrivals of the species from the north where they spent the summer as well as late migration to the north where they bred after having spent the winter roaming Pennsylvania fields and waterways. He mentions in the account that the first breeding of American Canada Goose did not occur until 1937 when a few pinioned geese released a few years earlier were successful in breeding in the state.

Today the Canada Goose is almost TOO prevalent for many residents. County and state parks, farm ponds, golf courses, and lawns adjacent to the three rivers seem to be very littered with “fertilizer” which prevents people from running barefoot on the lawns. There are actually professional Geese Police who use Border Collies to chase the geese away from unwanted areas, especially those where lethal means cannot be used. Loud noises have also been used, but as soon as the noises cease or the Border Collies leave, the geese return to foul the lawns and make the water “foul” also. Goose droppings contribute to over fertilization of ponds and lakes causing algal blooms which can be harmful to native fish, invertebrates, and the natural ecosystems of our waterways

Hunting is the only guaranteed method of keeping the resident Canada Goose population in check, of course only in areas where hunting is safe and legal. Hunting can reduce the negative impacts of a species that was not historically a year-round resident. In areas where the practice is safe, legal, and well-regulated, hunting can help to restore ecosystems, reduce local nuisances, provide nutritious food, and get people outdoors! Although the nuisance goose season has liberal bag limits, populations of the birds continue to increase.

Goose recipes can be found on the web using a simple Google Search. There are those who love the taste of a well-prepared bird, and those who think the meat is unfit for human consumption. Make a friend with a goose hunter and you can decide yourself.

Biography of Mr. Todd: https://sora.unm.edu/sites/default/files/journals/auk/v087n04/p0635-p0649.pdf

Book review: https://sora.unm.edu/sites/default/files/journals/auk/v057n04/p0579-p0595.pdf

Canada Goose sounds: https://www.allaboutbirds.org/guide/Canada_Goose/sounds

Stephen Rogers is Collection Manager in the Section of Birds at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

Mesozoic Monthly: Gryposaurus

The Late Cretaceous-aged (~75 million-year-old) large-nosed North American hadrosaur (aka duck-billed dinosaur) *Gryposaurus* by ginjaraptor on DeviantArt.

Anyone who frequents the Pittsburgh area is familiar with ‘Pittsburghese,’ the regional dialect given full voice in what was once voted America’s ugliest accent (a fact that does not diminish our pride for it). One of my personal favorite Pittsburghese words is “nebby,” which translates to “nosy” for any non-local readers. “Nebby” can be used in a variety of contexts: the distant relative asking prying questions about your love life at Thanksgiving dinner is nebby, the pet cat trying to crawl under the bathroom door to see what you’re doing is nebby, and even the statue of Carnegie Museum of Natural History mascot Dippy the Diplodocus, silently judging your driving on Forbes Avenue, is nebby. We can assume other dinosaurs were nebby too, since so many had huge noses to stick into things. One of the biggest noses in the fossil record belongs to Gryposaurus notabilis, the star of this edition of Mesozoic Monthly.

Gryposaurus belongs to a group of dinosaurs called hadrosaurs, which are commonly referred to as duck-billed dinosaurs. Hadrosaurs were herbivores that got their nickname from the flat, toothless, somewhat duck-like beaks at the tips of their jaws. These beaks were used to bite through tough vegetation so that it could be ground up by the numerous teeth embedded in the rear half of the jaws. There are two main groups of hadrosaurs, both of which are featured in CMNH’s Dinosaurs in Their Time exhibition. Probably the more famous group is the Lambeosaurinae, known for their distinctive head crests that housed extra-long nasal passages. Virtually everyone can recognize the incredible backward-curving crest of Parasaurolophus (featured multiple times in the Jurassic Park franchise), and visitors to CMNH will also know the helmet-like crest of Corythosaurus. The second group is the Saurolophinae (traditionally known as the Hadrosaurinae), which typically lack bony crests. You can find a simulated carcass of the saurolophine Edmontosaurus (lovingly known to those of us in CMNH’s Section of Vertebrate Paleontology as “Dead Ed”) between the two imposing Tyrannosaurus skeletons in Dinosaurs in Their Time.

A gallery of hadrosaur heads. Top left: the lambeosaurine *Parasaurolophus* at the Field Museum of Natural History in Chicago (photo by the author). Top right: the lambeosaurine *Corythosaurus* at Carnegie Museum of Natural History (photo from Wikimedia Commons). Bottom left: the saurolophine *Edmontosaurus* at the Houston Museum of Natural Science (photo from Wikimedia Commons). Bottom right: the saurolophine *Gryposaurus* at the Natural History Museum of Utah in Salt Lake City (photo from Wikimedia Commons).

As a crestless hadrosaur, Gryposaurus was a saurolophine. Despite its lack of crest, its skull still had pizzazz: its nasal bone arched dramatically, giving the impression of a ‘Roman nose’ (which is very noticeable if you compare the skulls of Edmontosaurus and Gryposaurus in the image above). The name Gryposaurus notabilis means “notable hooked-nose lizard” in homage to this feature. G. notabilis is the type species of Gryposaurus; type species are typically the first ones to be named in a genus, and therefore become the reference to which all new specimens that may belong to that genus are compared. The other species (such as G. monumentensis, shown in the photo montage above) are similar enough to the type species that they can be referred to the genus Gryposaurus, but they differ in too many ways to be assigned to G. notabilis itself.

Occasionally, paleontologists will revisit a fossil species or genus and decide that it is either too similar to another to justify its own name or that certain specimens are too different to be grouped under the same name. Kritosaurus, another saurolophine with a ‘Roman nose,’ has fallen victim to both of these circumstances. It was originally considered its own genus, but was subsequently revisited by paleontologists who decided that it was so similar to Gryposaurus that the two genera were lumped together under the name Gryposaurus (when combining taxonomic groups, the first name that was published is the one that gets used). However, later paleontologists reviewed the evidence again and split a single species of Kritosaurus back out of Gryposaurus. The famous sauropod (giant long-necked herbivorous dinosaur) Brontosaurus underwent a similar series of changes over the years: originally, it and Apatosaurus were considered different animals, but after a review they were lumped together under Apatosaurus. Recently, the two were split apart again and the name Brontosaurus was revived (to the delight of fans of that name around the world).

It is not uncommon in paleontology for species to be lumped or split based on new or revisited evidence. When you consider that the decision to name new fossil species is often based on fragmentary, highly incomplete skeletons, you can see why it might be difficult to get things right the first time! These changes sometimes give people the impression that paleontologists “can’t make up their minds” or “contradict themselves,” but we must remember two things. First, that science is meant to change based on new evidence. Second, there have been thousands of paleontologists over the course of history, and every one of them is an individual person who can draw their own conclusions based on the same evidence. Although the resulting changes can disappoint fans of a specific animal or hypothesis, revision is normal and beneficial for the field as a whole. Scientists are supposed to be nebby – it’s how we make new discoveries!

Lindsay Kastroll is a volunteer and paleontology student working in the Section of Vertebrate Paleontology at Carnegie Museum of Natural History. Museum staff, volunteers, and interns are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

Overwintering for Amphibians and Reptiles

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Feeding the Monster in the Sewer

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From the Allegheny to our Kitchen Sinks

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Canada Goose

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