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The Mother Spiders That Produce Milk For Their Offspring

Everyone can remember learning about mammals in preschool and early gradeschool. We were taught that only mammalian animals produce milk for the purposes of nourishing their offspring. While this is not exactly accurate due to the many non-mammalian lifeforms that also produce milk, it was good enough at the age of six. However, many people may be surprised to learn that a spider species has recently been discovered that produces its own nourishing fluid for its suckling spiderlings. This spider species is known as Toxeus magnus, and it is also notable for looking exactly like an ant in order to fool predators.

The Toxeus magnus is a species of jumping spider that is native to southeast Asia. Female spiders of this species produce a fluid containing sugars, fats, and proteins in order to provide their babies with nourishment. The lead researcher investigating this new spider species, biologist Rui-Chang Quan of the Chinese Academy of Sciences, is referring to this fluid as “milk” for the time being, as such a substance has never been found before. Interestingly, researchers learned that the spiderlings continue feeding on their mother’s milk well into maturity, which is unusual.

While spiders are not known for producing their own milk, a female spider’s parenting behavior is quite similar to mammalian parenting behaviors. Although many spider species are naturally solitary, many female spiders provide extended care for their offspring. For example, some female spiders avoid eating in order to constantly guard their egg cases, and other females will open their egg cases in order to give their spiderlings an occasional ride on their back. Other females even regurgitate food for their young, like birds do, but the recently discovered species of spider developed the ability to produce nourishing milk. Much like mammals, Toxeus magnus spiderlings are entirely dependent on their mother’s milk for survival. The researchers that found this spider species are convinced that many other spider species exist that also produce milk for their young, only they have yet to be discovered.

Do you know of any insect species that produce milk for their offspring?

Big City Spiders Are Less Afraid of Light Than Their Country Cousins

Spiders in general aren’t known for running around in the daylight. They tend to stick to dark corners, as this helps them better hunt unsuspecting prey and it helps them hide from other possible predators. However, there is one situation in which a spider has a bigger advantage working with light; if the spider in question is a web-weaving spider. Prey such as moths are attracted to sources of light such as street lamps. However, these kinds of light-emitting objects also tend to be located in more urban and suburban areas. Tomer Czaczkes of the University of Regensburg, in Germany, believes that because of this, at least one species of urban web-spinning spider has lost its fear of light, or photophobia, in order to set up their web near such lights and take advantage of the better access to prey attracted to light.Waco Spider Control

It was after seeing many well-fed and happy spiders building their webs near streetlamps in Regensburg that Dr. Czaczkes began to wonder if city life has changed spiders’ behavior. When he found out that urban moth populations are less attracted to light than their rural cousins, he thought that the reverse might be true for urban spiders. Urban spiders should be more attracted to, or less afraid of, lights than rural spiders. To see if his theory was true Dr. Czaczkes and his colleagues took 783 spiderlings from both rural and urban areas, as well as a number of different countries, and placed them in boxes individually that had a board dividing the space in half. He lit one side of each box with a lamp that produced no heat, and left the other side dark, with two tiny gaps allowing the spiderlings to cross between the two sides. After randomly placing each spiderling in either the dark or light side of the box, the researching then watched to see in which side they built their web.

The results were exactly as Dr. Czaczkes expected they would be. Two thirds of the spiderlings collected from rural locations built their webs in the dark side of the box. Their urban cousins, however, only built half of their webs in the dark side, suggesting that the urban spiders were indeed less afraid of light. The rural spiders were still very photophobic, but the urban spiders had adapted to the point where they did not exactly like the light, but had at least ceased to fear it.

Have you ever noticed how many spider webs in urban areas are close to light fixtures? Have you noticed less spiders hanging around near lights in rural areas?

Spider Prevention Tips | Waco Pest Control

Spider Prevention Tips | Waco Pest Control

  • Keep garages, attics and basements clean and clutter-free. Most spiders seek out secluded, undisturbed areas where they can build a web to catch their next meal, so an attic or basement that has been left unused over the past season could be harboring these pests out of sight. Avoid leaving clothing and shoes on the floor and consider storing them inside plastic containers.
  • Seal any cracks or crevices around the home. Spiders can crawl into homes through damaged window screens or cracks in the siding and foundation of a home.
  • Inspect items such as boxes of decorations and grocery bags before bringing them indoors. Packages are often left on the front step when delivered, and groceries might be placed on the driveway while unloading. These are opportunities for spiders and other pests to crawl onto bags and boxes and be carried inside.
  • If a spider bites you, contact your primary care physician for medical advice. Species such as house spiders and cellar spiders pose no health threat to people. Other species such as black widow spiders and brown recluse spiders do have the ability to pierce the skin and inject venom. Their bites cause varied reactions in people, but are very rarely fatal with proper treatment.

Spiders Might Have a Favorite Color Too

Most people believe that humans are the only or one of the only animals on this planet that can see in color. Until now scientists didn’t think insects could see in color, but that fact has just been proven wrong. Scientists recently discovered that peacock spiders can actually see colors, and have the color vision necessary to see and appreciate the male’s brightly colored bodies and their display to attract females. But researchers aren’t stopping there. Now scientists want to see if other spiders with less colorful bodies also have the ability to see in partial or full color.

George Uetz, a biology professor at the University of Cincinnati, joined together with his students to see if the plain old brown wolf spider has color vision. “The assumption was wolf spiders don’t pay attention to color. But we found that isn’t really true,” Uetz said. “We need to look more closely at the neurobiology of their eyes. We need to understand what their retinas do.” Humans have what is called trichromatic vision, which means we have retinal cells that are designed to see red, blue, and green. Uetz and his students found that wolf spiders actually have dichromatic vision, which means they can only see green and ultraviolet colors. Basically, they are color blind, but they can see light in green wavelengths.

Uetz took a group of male and female wolf spiders and studied how they reacted to videos of a courting digital spider on different backgrounds. They changed the color, intensity, and contrast of the background to see how they reacted. The female spiders proved more interested in the videos where the male spider contrasted sharply from the background. The female spiders also reacted more to the color and monochrome backgrounds, rather than the grayscale one, suggesting that color does indeed make a difference to spiders. For the females the intensity seemed to matter more than color, but with the males they showed the videos to, the color also matters. Another thing Uetz discovered was that the spiders’ eyesight also appears to adapt to the changing seasons.

Do you think other spiders see in color? Which ones do you think see the most colors on the light spectrum, such as red, green, and blue like us humans?