Ecosystems Archives

July 26, 2022July 25, 2022

Flower Crab Spiders and Camouflage

An unlimited number of features in the world around us speak of God’s design and wisdom. Consider flower crab spiders with the scientific name Misumena vatia. They earn the “crab” name because they resemble crabs and can walk forward, backward, and even sideways like crabs. Their two front legs are longer and extend out for grabbing prey, which they immobilize by injecting venom. Misumena vatia spiders don’t build webs to catch prey. Instead, they sit on a flower and capture incoming prey with their legs.

Another unique feature of these flower crab spiders is they can change color. The females, which are much larger than the males, have the options of white, yellow, or pale green. White is the baseline color. If they eat colorful prey, they can temporarily take on the prey’s color. For example, their abdomens will turn pink after a meal of red-eyed fruit flies. More commonly, if they sit on a yellow flower, they can secrete a yellow fluid into their outer body cells to give them a yellow color. Unlike chameleons that can change color in seconds, it takes days for Misumena vatia spiders to change their color.

When these spiders sit on yellow flowers, they are difficult for humans to see. However, they become highly visible to humans when they are white and perched for hunting on pink or red flowers. On the other hand, the arthropods that are both predators and prey for flower crab spiders have vision tuned for ultraviolet and blues. To them, the red in the flowers and the white of the spider appear dark to provide camouflage.

Flower crab spiders fill a unique ecological niche. They provide balance for the many life forms that feed on spiders and for the pollinators and plants. God has given us a diverse and beautiful natural world. Unfortunately, we take all this for granted, but when we look carefully, we see design in living things.

Reference: The Spokane, Washington, Spokesman-Review for July 13, 2022, page A01, and Wikipedia.

July 6, 2022July 9, 2022

Flies Provide Useful Functions

We are all familiar with houseflies except those readers in Iceland, where they don’t have any. We may not realize that, like all living things, flies provide useful functions and demonstrate incredible design.

Most of us know that flies can spread diseases such as salmonella, E.coli, chlamydia, typhoid fever, dysentery, cholera, polio, anthrax, leprosy, and tuberculosis. That’s because by using chemical receptors in their foot pads, flies can smell rotting organic waste. They land on garbage or dead animals, vomit digestive enzymes onto them, and lap up the liquified remains with a sponge-like tongue. In this way, they help to decompose and remove organic waste. However, they can pick up bacteria and carry them to humans.

Flies have glandular pads on the soles of their feet that secret a fluid that adheres to any solid surface. That adhesion is greater than the force of gravity, allowing the fly to walk up a wall or upside down on a ceiling. Flies can only fly about 4 miles per hour, so they become food for other life forms.

Flies in their larval stage are called maggots. Because they are sterile, green bottle fly maggots (Lucilia sericata) are used to treat wounds that don’t respond to antibiotics. The fly larvae also promote the healing of diabetic ulcers, gangrene, and burns by stimulating blood flow to the injured areas. In addition, they have been used to treat MRSA (a bacterial infection resistant to antibiotics) because they eat the dead and decaying flesh caused by the bacteria.

There is no question that humans need to restrict fly numbers and avoid contact with them. At the same time, flies provide useful functions and demonstrate incredible design. They are an important food for frogs and other animals and helpful in treating the medical problems of humans. Nothing in nature is evil or malicious because God created all of life with a purpose and function. That is even true of the housefly.

Reference: Sheryl Myers, founding director of Heart of the River Coalition in Anderson, Indiana.

July 2, 2022June 30, 2022

Historic Yellowstone Flood

You have probably heard about the historic Yellowstone flood that closed Yellowstone National Park earlier in June of 2022. On top of heavy rains, warm temperatures caused massive snow melt. The result was that Yellowstone River and its tributaries overflowed their banks, washed out roads in the park, and washed away buildings in the area. Thousands of people had to be evacuated from the park, and it was closed. The northern part of the park suffered the worst damage and is still closed at this time.

The Yellowstone River is the longest free-flowing river in the lower 48 United States. It flows for almost 700 miles without any dams to hold it back. Humans see this flooding as a disaster that will take years and millions of dollars to correct. However, from the standpoint of trees and animals, the flooding is a blessing. Cottonwood and willow trees along the river were declining. They serve to provide shade and shelter for bison, gray wolves, and grizzly bears. The flooding provided new moist soil and carried seeds, allowing new trees to sprout and grow.

When rivers don’t have an opportunity to overflow their banks, erosion deepens the channels, invasive plant species grow along the banks, and the floodplain wetlands dry up. When rivers run wild and overflow their banks, the surrounding wetlands store water and provide habitats for many birds and mammals. In addition, a raging river spreads new soil across the floodplain, reshaping and renewing the land. Scott Bosse, the director of American River’s Northern Rockies office, said, “As humans, we often think that floods are disastrous, and fires are disastrous, but they’re really only disastrous because we put human lives and property in harm’s way. They’re not disastrous from an ecological standpoint. Quite the contrary, they’re healthy for rivers, and especially for a river like the Yellowstone.”

This historic Yellowstone flood is not all bad. As far as the animals are concerned, they are probably relieved to have fewer humans around. The native cutthroat trout in the Yellowstone river can find new access to tributaries to spawn. At the same time, the introduced rainbow trout have had their eggs and fry washed away by the raging waters. The scouring of the river washed up a supply of invertebrates to provide meals for fish and birds. Ospreys, eagles, American dippers, and river otters benefit from a new food supply.

Meanwhile, the historic Yellowstone flood allows cottonwood and willow trees to release their seeds into the wet sandy soil to germinate. Cottonwoods are the dominant trees along the Yellowstone River, and the new trees will benefit breeding birds in the future. Because of the added soil moisture, the flood waters also benefit the grazing animals by giving them more plants to graze on.

Floods can benefit the ecosystem, but humans often build roads, homes, and other structures in floodplains. Or they build homes downstream from dams that have the potential to break and cause a worse flood. God gave us the responsibility to care for the Earth. To do that, we must first respect it and understand how natural systems work. In the long term, the Yellowstone River ecosystem and its tributaries benefit from the historic Yellowstone flood.

Reference: National Geographic “Historic Yellowstone Flooding Brings Renewal Despite Destruction” by S.J. Keller