Category: Invertebrates

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Spider Silk

Orb Spider Web
Contains 3 Types of Silk

Courtesy & Copyright 2011
Terry Greene, Photographer

Spider silk has long been of interest to scientists and engineers for its incredible strength. Silk can be, by weight, a stronger fiber than steel or Kevlar. But new research has discovered that the strength of the individual fibers does not explain the durability of a web, which can remain functional after sustaining extreme stress. The web’s overall design adds to silk’s durability to create a truly functional product.

Spiders utilize silk for many different reasons – transportation, lining burrows, protecting and securing egg cases, and of course for catching prey. Amazingly, an individual spider has the ability to manufacture several different types of silk, which are used for different purposes. In a typical orb-style web there are at least three kinds of silk at work. One is strong and dry, making up the ‘spokes’ of the web. These are the strands upon which the spider itself moves around, so as not to get stuck in its own trap. The strands which create the characteristic spiral pattern are actually made of two types of silk – one is a fine, stretchy fiber, and the other a sticky, glue-like substance. Together, these two silks make up the part of the web responsible for snaring prey.

Another important property of silk is that when stretched the fiber stiffens. As more pressure is applied, the properties of the silk change, allowing it to become stretchy and flexible. If still more pressure is added, the silk stiffens again, until finally it breaks. Originally, this stiff-stretchy-stiff response to stress was viewed as a weakness, but when analyzed as part of an interconnected web, that’s not the case. A team of scientists from MIT noted that webs could be subjected to a lot of force with only minimal damage. Whether the force was localized – for example while ensnaring a large insect – or more widespread over the entire surface – such as pressure from strong winds – the damage incurred by the web was minimal. Only the individual strands that endure the most pressure break, while others stiffen, flex, and remain intact.

Localized damage allows the spider to more often than not simply repair a web instead of abandoning it and starting over. Creating silk and weaving a web is a costly process for a spider – it takes up a lot of the arachnid’s energy. The ability to simply patch the broken parts is a more efficient strategy which requires less energy expenditure and fewer materials than weaving a new web.

Figuring out how to mimic this response to stress on a material could be infinitely useful in the human world. Imagine a skyscraper in an earthquake that fails in one small place where the forces are strongest – not in its entirety as is currently the case. That same earthquake-damaged building might also need only minimal repairs, saving time, money, and materials. Oh the lessons we could learn from one of nature’s smallest creatures…

Thank you to the Rocky Mountain Power Foundation for supporting the research and development of this Wild About Utah topic. For the Stokes Nature Center and Wild About Utah, this is Andrea Liberatore.

For the Stokes Nature Center and Wild About Utah, this is Andrea Liberatore.

Credits:
Images: Courtesy & Copyright 2011 Terry Greene
Text:     Andrea Liberatore, Stokes Nature Center in Logan Canyon.

Additional Reading:

Chandler, David L. (2012) How Spider Webs Achieve Their Strength. MIT News Office. Available online at: https://web.mit.edu/newsoffice/2012/spider-web-strength-0202.html

National Science Foundation press release (2012) A Spider Web’s Strength Lies in More Than its Silk. Available online at: https://www.nsf.gov/news/news_summ.jsp?cntn_id=123041

Law, Steven (2012) Curious Things About Spider Webs. Available online at: https://www.ksl.com/?nid=968&sid=20488145

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Pot Holes and Fairy Shrimp

Aerial view of potholes in Navajo sandstone, Grand County, Utah. Photo Courtesy USGS
Aerial view of potholes in Navajo sandstone, Grand County, Utah.

Photo Courtesy USGS 

Click to view larger image of , Photo Courtesy USGAdult fairy shrimp
Branchinecta packardi.
Photo Courtesy USGS 

Click to view larger image of Adult Vernal Pool Fairy Shrimp, Photo Courtesy USGSAdult Vernal Pool Fairy Shrimp
Branchinecta lynchi
Photo Courtesy USGS 
 

Shrimp in the desert landscape of Canyonlands National Park? Yep. You can find them, –fairy shrimp– when the rainy season arrives and turns dry, dusty potholes into water-filled rock basins brimming with life.

A surprising array of creatures relies on these potholes for life, and one of the most curious is the fairy shrimp. These unique crustaceans are found in small potholes that dot sandstone outcrops found in America’s Southwest. Their eggs maintain resilience during the dry season, and when spring rains arrive, the shrimp hatch.

There are more than 300 varieties of fairy shrimp, the most common being the Vernal Pool Fairy Shrimp. These little guys measure between a half-inch to one-and-a-half inches long as adults. They can be found anywhere ephemeral pools are present, though the majority of their population resides in California and Oregon.

Fairy shrimp vary in color depending on the menu found in their particular pool of residency, ranging from translucent, to orange, even to blue! They feature 11 pairs of legs to propel themselves upside-down, or more scientifically, ventral side-up.

They also use these incredibly helpful legs to eat unicellular algae, ciliates (sil-ee-its), and bacteria by filter and suspension feeding methods. They filter-feed by pumping water through filtration structures — located in their multi-purpose legs — thus capturing the food. They also are adept at suspension feeding by plucking food floating in the water, again, with their tentacle-like legs. They may also grab or scrape food from the surfaces of other things in their vernal pool, such as sticks and rocks.

What’s truly amazing is how fairy shrimp reproduce. They typically lay drought-tolerant eggs during the summer that over-winter in the dried sediment on the pot hole bottom and then hatch in the spring when the potholes fill with rainwater However, if drought sets in, eggs can be transferred to other pools by floating in gusts of wind or being carried by a particularly curious animal.

These eggs are tough and can withstand varying temperatures, drought, and even the test of time; eggs in laboratory settings have survived intact up to 15 years before hatching.

Under the right conditions, you can observe fairy shrimp in Canyonlands, Arches, and Death Valley national parks. Canyonlands and Arches boast at least two species of fairy shrimp: the Packard Ferry Shrimp, also known as the Rock Pool Ferry Shrimp or the Arizona Ferry Shrimp, and the Great Plains Ferry Shrimp.

Fairy shrimp hatch in the Spring, right after the potholes and vernal pools re-fill with water, so that will be your prime time to look for these interesting creatures. As travelers, you can do your part to help the fairy shrimp by leaving their vernal pools alone. Drinking water, stepping in, or touching a pool can throw off the entire mini-eco-system located in this fascinating habitat.

And remember, our fingers are very salty, so even if you’re using a gentle touch, do not put your fingers in a vernal pool, as it just might raise the salinity and throw off the dissolved oxygen percentage needed for fairy shrimp to survive.

For Wild About Utah and National Parks Traveler, I’m Kurt Repanshek.

Credits:
Image: Courtesy and Copyright Kurt Repanshek, www.nationalparkstraveler.com
Text:     Kurt Repanshek, NationalParksTraveler.com.
Additional Reading:

https://digitallibrary.utah.gov/awweb/awarchive?type=file&item=22782

https://www.nwf.org/wildlife/wildlife-library/invertebrates/vernal-pool-fairy-shrimp.aspx

https://www.arizonafairyshrimp.com/fairyshrimp.html

https://geochange.er.usgs.gov/sw/impacts/biology/vernal/

https://www.nasa.gov/centers/dryden/news/X-Press/shrimp_spotlight.html

https://www.fws.gov/sacramento/es_kids/Vernal-Pool-Fairy-Shrimp/es_kids_vernal-pool-fairy-shrimp.htm

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American Invasion

Eurasian Collared Dove, Courtesy invasivespecies.org, Joy Viola, Northwestern University, Photographer
Eurasian Collared Dove
Streptopelia decaocto
Courtesy & © invasivespecies.org/bugwood.org
Joy Viola, Northwestern University, Photographer

Colorado Potato Bug, Courtesy insectimages.org/bugwood.org, USDA ARS, PhotographerColorado Potato Beetle Adult
Leptinotarsa decemlineata
Courtesy IPMimages.org/bugwood.org
USDA ARS, Photographer

Hi, I’m Holly Strand from the Quinney College of Natural Resources at Utah State University.

More and more you are likely to hear this sound in Utah yards, parks and fields. [Eurasian Collared Dove, Courtesy Ryan O’Donnell, www.xeno-canto.org/98068] That’s the call of the Eurasian collared dove. Originally from Asia, this dove has been expanding its territory around the world at an incredible rate. The first sighting in Utah was in Orem in 1997. And now the doves are everywhere. So far, it doesn’t look like our native mourning dove is affected. But such rapid population explosions rarely occur without some sort of undesirable ecological consequence.

In America, the Eurasian collared dove is an invasive species. But not all non-native species are invasive. “Invasive” only applies when species spread far beyond the area where they are first introduced. Luckily, not all invasive species turn out to be serious pests. Ecologist Mark Williamson suggested the tens rule. About 10% of introduced species establish lasting populations and 10% of those go on to become problems.

There’s a long list of Eurasian invasives in Utah. Among them is the highly flammable cheat grass that comes from southwestern Asia. Those massive clouds of starlings? They come from Europe. Tamarisk from Eurasian deserts lines the Colorado River and tributaries. The common carp is an unwelcome Eurasian colonist of our lakes and large rivers. And the American west’s iconic tumbleweed is an invader from the Russian steppe.

Why so many invaders from Eurasia? Well for the last 500 years, there has been a net outflow of Eurasians—especially Europeans—to other parts of the world. And this human population carried its biological baggage along with it—in the form of animals, plants and diseases. Some ecologists believe that the physical geography and human history of Eurasia has conditioned its species in such a way that they will consistently outcompete the species of other continents. But that’s debatable. For in the last decades the New World has started to lob some pretty competitive species over to Eurasia.

For example, the American mink was brought to the Eurasian continent in the 1920s for use on fur farms. But–because of deliberate releases and accidental escapes–the mink is now common in the European wild. And it’s a pest. The American mink is taking the place of the European mink which is now threatened with extinction. Furthermore, the American mink is gobbling up populations of many ground-nesting birds.

Unless you are involved in agriculture, you might not have heard of the Colorado potato beetle. But potato growers around the globe know this striped orange and brown beetle from the American southwest very well. It has a voracious appetite for potato leaves and quickly develops resistance to any chemicals used against it.

And a final example: the American bullfrog is considered one of the world’s most damaging invasives. The bullfrog does amazingly well in a variety of habitats –even artificial ones like millponds, irrigation ditches and reservoirs. Its incredible adaptability helps it spread and outcompete native frogs. Moreover, it has been transmitting a deadly fungus to previously unaffected populations of frogs, toads and salamanders.

Thanks to Lyle Bingham for information on the Eurasian collared dove. And to Ryan ODonnell for his audio recording from xeno-canto.org. For more information on the Eurasian collared dove and other invasive species go to www.wildaboututah.org.

For Wild About Utah, and the Quinney College of Natural Resouces, I’m Holly Strand.

Credits:

Theme: Courtesy & Copyright Don Anderson Leaping Lulu
1. Photographer Joy Viola, Northwestern University, Bugwood.org https://www.invasive.org/browse/detail.cfm?imgnum=5413582
2. USDA ARS Photo Unit, USDA Agricultural Research Service, Bugwood. https://www.insectimages.org/browse/detail.cfm?imgnum=1321015

Audio of Eurasian collared dove:
Ryan P. O’Donnell, XC98068. Accessible at www.xeno-canto.org/98068.
Creative Commons Attribution-NonCommercial-NoDerivs 2.5

Text & Voice: Stokes Nature Center: Holly Strand

Sources & Additional Reading:

Bingham, Lyle. 2009. The New Dove in the Neighborhood. Wild About Utah Program https://wildaboututah.org/the-new-dove-in-the-neighborhood/ October 8, 2009.

di Castri F. 1989. History of biological invasions with special emphasis on the Old World. In: Drake JA, Mooney HA, di CastriF, Groves RH, Kruger FJ, Rejma´nek M, Williamson M, eds. Biological invasions: a global perspective. Chichester, UK: John Wiley and Sons.

European Environment Agency, 2012. The impacts of invasive alien species in Europe EEA Technical report No. 16/2012. EEA, Copenhagen.

National Invasive Species Information Center (NISIC): Gateway to invasive species information; covering Federal, State, local, and international sources.
https://www.invasivespeciesinfo.gov/index.shtml

Simberloff, Daniel. 2013. Invasive Species: What Everyone Needs to Know. Oxford University Press

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Sphinx Moths

Sphinx Moths: Big Poplar Sphinx, Pachysphinx occidentalis, Courtesy Whitney Cranshaw, Colorado State University, bugwood.org
Big Poplar Sphinx
Pachysphinx occidentalis
Courtesy Whitney Cranshaw
Colorado State University
bugwood.org

White-lined Sphinx
Hyles lineata
Courtesy Whitney Cranshaw
Colorado State University
bugwood.org

White-lined Sphinx Caterpillar
Hyles lineata
Courtesy Whitney Cranshaw
Colorado State University
bugwood.org

I vividly remember the first time I saw one – a small winged creature whirring from flower to flower in the evening light, its long tongue dipping for nectar within tube-shaped blooms. I was mesmerized, and struggled for a closer look.Sphinx Moths

If you’re thinking that I must have seen a hummingbird, you would be making a very common mistake. A mistake, in fact, that has given this critter one of its many nicknames. The winged wonder I saw that summer night was a sphinx moth, also called a hummingbird or hawk moth because of their large size and bird-like characteristics.

In all stages of their life, these insects are large. Caterpillars grow to a robust 4 inches in length and adult wingspans can measure more than 5 inches. Sphinx moths are also some of the fastest insects on earth and have been clocked flying at over 30 miles per hour. Their size, speed, and flying ability reflect those of the hummingbird so closely that they are commonly misidentified.

Sphinx moths are a beloved sight in many Utah gardens. However, they also hold a bit of a devious surprise. The larvae, or caterpillar, of one common species of sphinx moth are well known by vegetable gardeners. They are large and bright green with a distinctive horn near their hind end. Like the adults, these larvae go by many names, the most common being the tomato hornworm. Hornworm caterpillars, unlike their adult counterparts, are not beloved by gardeners. They are voracious beasts with the ability to strip the vegetation off a tomato or pepper plant in one day.

Aside from our garden plants, young hornworms of other species feed on a variety of vegetation including willow, poplar and cottonwood trees. Adult moths rely on a host of flowers such as columbine, honeysuckle, larkspur and evening primrose. Here in Utah you might come across one of a handful of different species in the sphinx moth family including the five-spotted hawk moth and the white-lined sphinx. Look for them in the late summer evenings as daylight begins to fade. But be sure to look twice to avoid mistaking them for something they’re not.

And the next time you find a hornworm on your tomatoes, maybe just relocate the little bugger so that you can enjoy it once metamorphosis changes the beast into a beauty.

For more information and pictures of our native sphinx moths, visit our website at www.wildaboututah.org. Thank you to Rocky Mountain Power Foundation for supporting the research and development of this Wild About Utah topic.

For the Stokes Nature Center and Wild About Utah, this is Andrea Liberatore.
Credits:

Photos: Courtesy Whitney Cranshaw, Colorado State University, Bugwood.org
            Images licensed under Creative Commons Attribution 3.0 License
Text:    Andrea Liberatore, Stokes Nature Center, logannature.org

Additional Reading:

Cranshaw, W.S. 2007. Hornworms and “Hummingbird” Moths. Colorado State University Fact Sheet 5.517. Found online at: https://www.ext.colostate.edu/pubs/insect/05517.pdf

Buchman, Steve. 2010. Pollinator of the Month: Hawk Moths or Sphinx Moths (Sphingidae). US Forest Service. Found online at: https://www.fs.fed.us/wildflowers/pollinators/pollinator-of-the-month/hawk_moths.shtml