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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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Utah Paper Wasps

Adult Poliste Paper Wasp, Courtesy and Copyright 2009 Jim Cane - All Rights Reserved
Adult Poliste Paper Wasp
Copyright © 2009 Jim Cane

We credit the Chinese with inventing paper 2000 years ago, but some social wasps have been making their paper nests for eons. Species of paper wasps are found throughout Utah.

The burly bald-faced hornet workers are patterned in black and white. They place their grey, basketball sized paper nests in tree branches.

Bold yellow and black striped Yellowjackets are the persistent unwelcome guests at summer picnics. They too wrap their round nests in an envelope of paper, but typically place it in a shallow underground chamber. Within the paper envelope, both hornets and yellowjackets have a muti-tiered stack of paper honeycombs, like an inverted pagoda.

Open-faced nest of Polistes  paper wasp with grub-like larvae, Courtesy and Copyright 2009 Jim Cane - All Rights Reserved
Open-faced nest of Polistes
paper wasp with grub-like larvae
Copyright © 2009 Jim Cane

Our most familiar paper wasps belong to the genus Polistes. These are the reddish-brown spindly looking wasps. They make their simple paper nests under your home’s roof eaves and deck railings. A Polistes nest consists of a single inverted paper honeycomb suspended from a stiff, short stalk. There is no paper envelope, so you can readily see the hexagonal paper cells. Around your yard, look for the workers scraping fibers from weathered wood surfaces. Workers mix the chewed fibers with saliva and water, carry the ball of wood pulp home, and add it to the thin sheets of their paper nest. The nest is their nursery, where you can see the queen’s tiny sausage shaped eggs and the fat white grubs. The grubs are fed by their sisters, the workers, who scour the surrounding habitat for insect prey or damaged fruit.

The enclosed nest of the bald-faced hornet Copyright © 2009 Jim Cane - All Rights Reserved
The enclosed nest of the
bald-faced hornet
Copyright © 2009 Jim Cane

Utah has been invaded by the European species Polistes dominula. These interlopers are displacing our native Polistes. Where these European Polistes wasps are a stinging nuisance, you can easily dispatch them at their nests with a sprayed solution of dishwashing detergent and water. Thus stripped of its clever defenders, take the opportunity to admire their homes of paper.

This is Linda Kervin for Bridgerland Audubon Society.

Credits:

Photo: Courtesy and © Copyright 2009 Jim Cane

Text: Jim Cane, Bridgerland Audubon Society

Additional Reading:

https://extension.usu.edu/files/publications/factsheet/yellowjackets-hornets-wasps09.pdf

https://ohioline.osu.edu/hyg-fact/2000/2077.html

https://insects.tamu.edu/fieldguide/cimg348.html

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Wildfires in Utah

Wildfires in Utah: Click to view larger image of Fireweed growing in burned area, Photo Courtesy US FWS, U.S. Fish and Wildlife Service
Fireweed Grows in Burned Area
Photo Courtesy
U.S. Fish and Wildlife Service

Hi, this is Mark Larese-Casanova from the Utah Master Naturalist Program at Utah State University Extension.

Prior to settlement by the pioneers at the end of the 19th century, wildfires were relatively common throughout the mountains of Utah. Wildfires were a result of natural disturbance, such as lightning strikes, but many were purposely set by Native Americans. Wildfires restarted the cycle of forest succession and also created a mosaic of plant communities across the landscape.

Although Utah’s changing climate has had a major influence, human factors have considerably altered the natural fire regime over the past 150 years. Fire frequency slowly declined prior to settlement by the pioneers due to a period of global cooling; however, fire activity increased considerably to its highest point during the settlement period between 1856 and 1909. This increase was linked to the dramatic growth in human population and activity, which lead to increased surface fuel from extensive timber harvesting, and inevitably to more ignition sources for more frequent fires.

Between 1910 and 1990, there was a dramatic decline in wildfires throughout Utah, despite the gradual increase in global temperatures. This was due to intensive livestock grazing, habitat fragmentation as a result of development, agricultural expansion, and effective fire suppression. As a result, shade-intolerant trees that relied on fire for regeneration, such as aspen and lodgepole pine, were often replaced by long-lived, shade-tolerant trees, such as spruce and fir. In general, this resulted in a gradual decline in diversity of plant communities.

As a result, more homogenous forests that are densely populated with trees and accumulated fuels are more susceptible to intense fires that burn hotter and are more difficult to control. In 2007, Utah had a record-setting fire season that burned over 629,000 acres, including the 363,000-acre Milford Flat Fire. We’re halfway through the fire season this year, and approximately 400,000 acres have burned in Utah, costing over $47,000,000 to control. Additionally, wildfires that have burned about three-quarters of the acreage this year were classified as large in size. It seems that increased temperatures, decreased snowpack, and a century of land use and management has resulted in a dangerous wildfire situation in Utah and much of the West. It will take some creative management strategies, such as sustainable timber harvesting or prescribed fires, to tackle this ongoing issue if we want to limit the risk and cost of larger and more frequent wildfires.

For Wild About Utah, I’m Mark Larese-Casanova.

Credits:

Images: Courtesy U.S. Fish and Wildlife Service, images.fws.gov

Text:     Mark Larese-Casanova, Utah Master Naturalist Program at Utah State University Extension.
Additional Reading:

Madany, M. H., and N. E. West. (1983). Livestock grazing-fire regime interactions within montane forests of Zion National Park, Utah. Ecology 64:661-667., https://www.jstor.org/discover/10.2307/1937186?uid=3739928&uid=2&uid=4&uid=3739256&sid=21100946519023

Neugebauer, C. (Jul 15, 2012). Burning through money: the cost of Utah wildfires. Salt Lake Tribune., https://www.sltrib.com/sltrib/news/54485976-78/fire-fires-cost-costs.html.csp

Utah Fire Info webpage: https://www.utahfireinfo.gov/

Williams, J., D. Albright, A.A. Hoffmann, A. Eritsov, P.F. Moore, J.C.M. de Morais, M. Leonard, J.S. Miguel-Ayanz, G. Xanthopoulos, P. van Lierop. (2011). Findings and implications from a coarse-scale global assessment of recent mega-fires. 5th International Wildland Fire Conference. Sun City, South Africa., https://www.fao.org/docrep/014/am663e/am663e00.pdf

Live Worldwide Network for Lightning and Thunderstorms in Real Time, Blitzortung, https://en.blitzortung.org/live_lightning_maps.php?map=30

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A Modern Day Phoenix

“Phoenix,” an immature Golden Eagle
Aquila chrysaetos
Courtesy Wildlife Rehabilitation Center of Northern Utah (WRCNU.org)

Elk Bath
From a 2000 fire in the
Bitterroot National Forest in Montana

Courtesy Wikimedia &
USDA Forest Service
John McColgan, Photographer

Hi, I’m Holly Strand.

You may have heard about the golden eagle nestling that was badly burned during a recent Utah wildfire. Its nest was totally destroyed, but the little eagle had fallen to the ground and survived. After the fire, he was found by Kent Keller, a volunteer for Utah’s Div. of Natural Resources, who had banded the young eagle a month before. The eagle was dehydrated—his feathers, face, and feet were badly burned. So Keller obtained a permit from wildlife officials to intervene. Now in the care of the Wildlife Rehabilitation Center of Northern Utah the eagle is recovering rapidly. Even so, it will take a while for the damaged feathers to be replaced by healthy new ones. Phoenix–as is he was aptly named–won’t learn to fly for at least another year.

With this and other fire-related stories in the news, I‘ve been wondering about the fate of animals caught in wildfires. Scientific observations of animal behavior during fire events are rare. But by conducting post-fire surveys, and comparing results with unburned areas, some researchers have been able to piece together an idea of who survives, who dies and who thrives.

Obviously, faster and more mobile animals have the advantage. Birds can fly away and most mammals can outrun the spreading flames. Spring fires can be disastrous, destroying birds who haven’t fledged –like Phoenix– or mammals who are still too immature to escape. Fortunately, fires are more frequent in mid to late summer when little ones have matured.

If a fire moves through an area quickly, without superheating the ground, dormant animals or those hiding in burrows can survive. The surrounding soil provides plenty of insulation. Soil also protects most soil macrofauna and the pupae of many insects.

Animals that live their lives totally or partially in the water may not suffer at all during a fire. However, smaller bodies of water, such as streams, can quickly heat up fairly quickly. Oxygen loss is a problem as well. And fire-fighting chemicals dumped from the air can end up in water, killing fish, frogs and other animals.

Indirectly, the alteration of habitat by fire can also restructure animal populations. Interestingly, there are quite a lot of animals that benefit from post-fire habitats. For example, the insect population above ground may plummet during a fire, but then increase above pre-fire levels when fresh young plants start to grow back. Burned trees are attractive to certain beetles as breeding sites. An increase in beetles is a windfall for the woodpeckers that devour them. Swallows and flycatchers use burned dead trees as perch sites. They survey from on high and then swoop to catch their insect dinner. Seed eating birds like Clark’s Nutcracker, gobble up conifer seeds when cones open in response to fire.

Among mammals, ground squirrels, pocket gophers and deer mice generally increase after severe fires. Even large herbivores such as pronghorn or deer may benefit from the increased food and nutrition on recent burns. In turn, predators of these creatures enjoy a bumper crop as well.

For images of Phoenix the recovering golden eagle and a link to the Wildlife Rehabilitation Center of Northern Utah go to www.wildaboututah.org.

For Wild About Utah, I’m Holly Strand.

Credits:

Images: Courtesy Wikimedia, Louis Agassiz Fuertes, Gavin Keefe Schaefer and Dave Menke, US FWS images.fws.gov
Text: Holly Strand

Sources & Additional Reading:


Baker, William L. 2009. Fire ecology in Rocky Mountain Landscapes. Washington, DC: Island Press.https://islandpress.org/ip/books/book/islandpress/F/bo7019409.html

Bradley, Anne F.; Noste, Nonan V.; Fischer, William C. 1992. Fire ecology of forests and woodlands in Utah. Gen. Tech. Rep. INT-287. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. https://www.fs.fed.us/rm/pubs_int/int_gtr287.pdf

Hutto, RL. 1995. Composition of bird communities following stand-replacement fires in northern Rocky-Mountain (USA) conifer forests in Conservation Biology Volume: 9 Issue: 5 Pages: 1041-1058 https://www.fsl.orst.edu/ltep/Biscuit/Biscuit_files/Refs/Hulto%20CB1995%20fire%20birds.pdf

Wildlife Rehabilitation Center of Northern Utah https://wrcnu.org/