How come there are no blue or green mammals?

Have you ever thought about this? Think about it for a minute. If you were to list 10 mammals off the top of your head – perhaps animals like your dog, cat, an elephant, rat, zebra, skunk, raccoon, opossum, bobcat, or even a coyote – you would quickly realize that the colors of these mammals lack blue and green hues. There are a couple of reasons as to why this is, and why other animals like insects, birds, amphibians, and reptiles exhibit these colors quite often.

The reason has to do with chemistry primarily. First off, let’s talk about what produces colors in living things. Pigments are chemical compounds that are responsible for producing color in the biological world. When pigments absorb light, they reflect back certain wavelengths, producing colors our eyes can perceive. Plants, for example, have many different kinds of pigments with all kinds of peculiar names, such as carotenoids, flavonoids, and anthocyanins. Thousands of these chemicals have been identified by scientists and this is the reason why plants can produce a vast array of colors – from the dominant green leaves, to different shades of bark on trees, to the orange color of a carrot, the colorful fruits and flowers there are and the beautiful foliage colors we see during autumn in temperate latitudes.

When it comes to animals however, things are a bit different. The vast majority of animals simply do not have the variety of pigments that plants do. Specifically, they are not able to genetically produce blue and green pigments. Then how come we still see animals that are those colors? There’s blue butterflies, green frogs, and peacocks are well-known for their blue feathers! Most of these animals produce this color through a phenomenon known as structural coloration, which is the optical illusion of a color, essentially. Small structures of the skin scatter and reflect back light in a way so that only the blue wavelengths reach our eyes. But, in reality, there is no blue pigment doing that. When it comes to green, usually there is a yellow pigment involved with a structural blue coloration.

For instance, when a rough green snake (Opheodrys aestivus), a common River Legacy snake, dies, it turns blue because the yellow pigment is no longer being produced but the structural color is still there. Another way animals are able to produce vibrant colors is by obtaining pigments from their environment, typically their diet. This is how flamingos develop their typical pink to red hue, by eating foods like algae, shrimp, and crabs that have these pigments in them. A similar phenomenon occurs with the northern cardinal (Cardinalis cardinalis), another River Legacy common sight.

Now, let’s go back to mammals. Mammals have not been able to evolve or have lost the ability to implement pigments obtained through their diet to the same extent as other animals have. It happens but not to the same degree. This is why eating something like beets can turn the toilet a certain color when we go to the bathroom but it does not turn our skin purple. When it comes to naturally-produced pigments, mammals really only produce one kind – melanin. Melanin is an important pigment that provides protection against the sun’s damaging UV rays but it also is responsible for the majority of colors in mammalian skin. It comes in two kinds – eumelanin (responsible for black and brown colors) and pheomelanin (responsible for yellow or reddish to brown colors). Very few mammals, like mandrills (a type of African monkey), are able to produce small amounts of blue color through structural coloration.

But, how come no other mammals can? Scientists are not really sure but it may have had to do with the evolutionary history of mammals. Early mammals survived during the Mesozoic era, the golden age of the dinosaurs, by basically not being around them too much in order to avoid becoming food or by not trying to compete with them for the same resources. It is believed that most dinosaurs were active during the day so it is most likely that mammals had to turn to a largely nocturnal lifestyle. This meant that mammals did not have the need to develop adaptations that were not necessary in the night, such as the ability to see a wide range of vibrant colors. If there was no selective pressure (i.e. need) for either evolving structural coloration, pigment formation, or the ability to obtain pigments through diet, then the genes that allowed for those traits disappeared from the mammalian gene pool. The majority of animals today, with the exception of most mammals, have stellar color vision. On the other hand, as a result of their evolutionary history, mammals tend to be color-blind when it comes to blue and green colors. The big exception to this are primates – the group to which humans and mandrills belong. Therefore, it is hypothesized that as a result of all of this, the vast majority of mammals lack green or blue colors on their skin or fur.

What an incredible and fascinating subject to be sure. Next time you take a hike in the River Legacy trails and you come across a mammal – whether it be a squirrel, bobcat, or rabbit – you will know why those creatures are not flashing blue and green at you!

Recent Bobcat Sightings

Bobcats (Lynx rufus) are well-known inhabitants of our woods! These cats are usually very secretive but, every once in a while, they are spotted walking openly on our paved trails where people can see them. Unlike most mammals, bobcats are still active despite the increasingly colder days. During fall and winter, they become more diurnal as their prey (rabbits and rodents, mainly) is more active at daylight during those seasons. So, it is possible that more bobcats are going to be seen in the next coming weeks and months. Bobcats, in general, are not aggressive species. It is incredibly rare for bobcats to present danger to people. Nevertheless, here are some things you should know if you happen to encounter a bobcat:

  • Stay within a reasonable distance of the bobcat. If you start getting too close to it, it might think you present a threat. Naturally, it would want to defend itself.
  • If the bobcat starts to walk toward you, which is incredibly rare, slowly start backing away. It is important that you do not run as this might scare the bobcat.
  • Do not touch or attempt to feed the bobcat. Bobcats are wild animals and you always want to minimize opportunities for them to bite. As it is the case with most wild mammals, wild bobcats may be rabid at times. Feeding any wild animal can cause harm to the animal, and there are plenty of food resources in River Legacy Park.
  • If a bobcat decides to walk by you, as long as you do not try to kick it or make sudden movements, the bobcat will just continue on its way.
  • Always have your pets on a controlled leash. The last thing you want is any altercation between a wild bobcat and your dog.
  • Be sure to take a picture and/or video of your bobcat encounter from a safe distance!

Seeing bobcats is a neat experience and if you find yourself in that situation and, as long as you follow these precautions, you will be able to enjoy being in the presence of these wonderful cats!

 

Bobcat (Lynx rufus) seen near the entrance of River Legacy Living Science Center last Saturday, November 10th, 2018!

Why is water important anyway?

Water is a vital resource for life. We have all seen or heard this statement since we can remember. But, what makes water unique for living organisms, from humans to blue whales to bacteria to mushrooms?

While entire articles and books can be written on the subject, here are just a few facts that make water essential:

  • Water has the amazing ability to carry out a vast amount of chemical processes in contrast to many other liquids because of its chemical structure. This allows for humans, plants, and animals to undergo all of the processes they need for survival, from digestion to respiration to photosynthesis. No other liquid would allow for ALL of these to take place.
  • Water prevents things from becoming dry. Since most organisms are majority water, this is key for survival in harsh conditions such as the desert. Without it, animals and plants would literally dry up and harden, dying in the process.
  • Water actually becomes less dense as it freezes. This is something unique to water and it is the primary reason why ice floats. Without this property, our planet’s weather would be drastically different, affecting all life on Earth.
  • Water can absorb a lot of heat before it actually starts heating up in comparison to other liquids. This is the reason why areas where there is a massive body of water nearby tend to be cooler than inland areas (for example, cities by a lake or the ocean). This also makes water an incredibly effective cooling mechanism.

The list goes on and on. Water is constantly being cycled; it goes from the clouds in the form of rain, to the plants and animals in the ground and to reservoirs, lakes, and streams. From there, it either continues to flow until it eventually makes its way into the ocean or it goes to our homes for consumption after a rigorous purification process. Water from our homes eventually rejoins the cycle. All water then ends up in the ocean where it can evaporate into the atmosphere, ready to fall back down as rain. Despite this seemingly never-ending cycle, at the end of the day, water is a finite resource. There was a time when our planet did not have any water and that happening again in the future cannot be ruled out. Therefore, it is very important that we conserve water. Conserving water is also financially smart in the long-run, both for cities and people’s homes.

If you would like to know more about the purification process water goes through, allowing us to be good water conservationists, we invite you to our first Conservation Saturday event at 11 am, Sept. 22. There will be a family-friendly presentation on water conservation, and families will have a chance to create a water bottle water filter. Spaces are filling up quick, so if you would like to sign up, please call 817.860.6752 to RSVP. We hope to see you there!

Spider venom!

Last year, we talked about spiders and their benefits to nature. Today, we revisit spiders to talk about a very interesting trait they have – their venom. Almost all 46,000 spider species have venom. Fortunately for us, there are only a very few that can actually harm people. In our area, there are only two types of spiders of concern: the black widow and the brown recluse spider. Black widows are distinctively black and have a red or orange shape on the back of their belly while brown recluses tend to have a violin-like shape on the back of their thorax.

Spiders primarily use their venom to paralyze prey so they can eat it. The venom is injected into the insect through the spider’s fangs. Spider venom usually is one of two types. Certain spiders produce neurotoxins, which attacks the nervous system of the prey. Other spiders produce cytotoxins, which help in turning the prey into liquid form. This makes it easier for the spider to consume it. In many ways, spider venom is not that different from snake venom.

If you would like to watch a spider eat, we invite you to our public feedings on Fridays at 4:30 pm to see our Texas brown tarantula (Aphonopelma hentzi) eat in his exhibit. Usually the venom will not be seen, but you can be assured the spider is using it to eat its food!

Left: Our Chilean rose hair tarantula eating a cricket. A venom drop, in white, can be seen on the right side of the mouth.

The Armadillo and the Bobcat

 

 

 

 

 

 

 

Exiting the back doors of the Science Center, I headed out for a walk. To my right was a Texas persimmon, bordered by layers of the scarlet turk’s cap, a beautiful plant with flowers deeply red. The large stone steps escorted me down to the level of the trails.

Overhead hung vines, whose mustang grapes quietly tumble to the ground and are squished by herds of wandering feet. I walked further, passing the American pokeweed, a plant which hides its toxicity behind its blueberry-like appearance. To my left, a forking trail leads to an alleyway of poison ivy, appropriately labeled so that onlookers can observe without risk.

Finally, I reached my destination – the pedestrian bridge, whose sturdy wooden panels are upheld by the strength of red metal framing. Beneath this bridge flows Snider Creek, which on this day was dry from weeks of Texas heat and drought. I leaned over the edge to look.

Along the dry creek bed I saw movement. What was this bizarre creature? A medium-sized body, slender, coated in a thin layer of light brown fur. I struggled to identify it. But as it turned its head upward, facing me, the uniqueness of its facial structure with its tufted ears, disclosed its identity. I was looking at a bobcat, my first time seeing one in the park.

I was mesmerized by this sighting; I’d wanted to see a bobcat for quite some time. But as the cat ran away, and I began to excitedly return to the building, I heard another noise, this time along the bank that lines the creek. I looked to my left to see an armadillo just beside the bridge digging in the dirt, slowly heading in the same direction as the bobcat.

What an incredible walk this had been. To see a bobcat in the park is a rare privilege, but to see one within 50 feet of an armadillo is remarkable. These creatures are vastly different. Both are mammals, but that concludes their overlap. One is lengthy and thin, walking with the elegance of the feline family. The other is spherical and armored, trudging along. How strange, then, to see these incredibly different animals in such close proximity.

But this is what one encounters along the River Legacy trails. Each walk is different. Some are calm and quite; others are filled with the humming of cicadas and the chirping of birds. During some, one sees young turtles, ribbon snakes, or eastern cottontail rabbits. On a rare occasion one might spot a beaver wading in the pond, its uppermost layer of fur made dark by the water. And on some lucky days, as I was fortunate enough to experience, you may see the astounding variation of the natural world displayed in front of you, as bobcats and armadillos wander along the same creek.

Come visit our trails and let us know what you find.

Written by Josh Ripple, a Summer Intern at River Legacy Living Science Center and student at Stanford University.

Beavers at River Legacy!

River Legacy is home to lots of very well-known mammal species such as bobcat, raccoon, squirrel, and armadillo. But, did you know that the North American beaver (Castor canadensis) also lives here? Here are some cool facts about one of River Legacy’s most secretive mammals.

  • Beavers are the second largest members of the rodents, after the South American capybara. They can weigh up to 71 pounds!
  • Beavers have an extra thick layer of fat under their skin. This helps with insulation from very cold water.
  • Beavers are incredible architects! They are able to construct their homes in rivers, streams, and/or lakes using twigs, mud, sticks, chewed-on trees, and other similar materials.
  • Beavers can remain underwater for up to 15 minutes!
  • Beavers can use their tail to slap it on the water to warn other beavers nearby of potential danger, such as predators.

Beavers are largely nocturnal. The best way to find them during the day is during the dawn hours. Walking the trails close to the Trinity River or Snyder Creek during this time could provide you with the wonderful experience of seeing a beaver! We’ve even spotted one in our pond recently at River Legacy Living Science Center!

Learn more about the beaver and other animal architects during our NEW Animal Architects Summer Class in July. Spaces are still available for the class which meets July 9-13 and July 16-20. Sign up online at www.riverlegacy.org or call 817.860.6752, ext. 102 to enroll today!

World Environment Day

Today, June 5th, the world celebrates World Environment Day! Since 1974, on this day, the United Nations has encouraged and promoted awareness and ways we can all help to take care of the environment.

One of our missions at River Legacy is conservation and preservation of the lands around the Trinity River. While not everyone can be involved in taking care of the forest, there are a few steps that you can take at home to be good stewards of the environment, especially on this very special day:

  • When doing laundry, try using your washer and drier only when you have a full load. You can help conserve water this way!
  • When watering your yard, do it in the early morning when it is cooler. If you do it in the middle of the day, the water will evaporate quickly. This is especially true during this hot season.
  • Try taking shorter showers as to conserve more water and replace your shower head with a low flow shower head!
  • Drink out of reusable water bottles versus plastic! Plastic takes thousands of years to decompose.
  • When at the office or school, try printing double-sided as to conserve paper. The less paper we waste, the less trees we are wasting.
  • Disconnect electrical appliances. Having them plugged in only uses up electricity. For example, your TV or computer when you’re not using them.

Starting in the Fall, we will have a new program dubbed Conservation Saturdays. This program will be centered around specific things we can do to help conserve natural resources such as water as well as all aspects of the forest. Stay tuned for more information in the next couple of weeks!

Beautiful Autumn Colors

As we welcome December, the end of fall is fast approaching. In fact, there are only 17 days left of autumn. While River Legacy and North Texas in general do not see much traditional autumn foliage, there are a few trees that exhibit some fall hues. By now, most of the leaves have begun to fall to the ground, but there are still some trees with their green, orange, brown, red, or yellow foliage.

But, what drives the leaf color change? It has to do with the chemistry inside the leaves and how it responds to seasonal changes. Leaves contain many pigments, including chlorophyll as well as carotenes, xanthophyll and others. Chlorophyll is probably the one most of us are familiar with. This is the pigment that gives leaves their green color. When a plant undergoes photosynthesis, the process by which it creates its own food, chlorophyll takes center stage. It absorbs energy from the sun’s rays to be used in creating this food. As autumn approaches, the temperature gets cooler and the length of sunlight the leaves receive shortens. This causes chlorophyll to break down, making the green color go away. So, leaves are left with the other pigments and these become visible. Carotenes and the other pigments give leaves their yellow to orange colors in the fall. There are other chemical processes at work that add the red hues that are commonly seen as well.

Eventually, the leaves break off the tree. Since trees will no longer be able to make their food during the winter, they go into a state of dormancy where their metabolism slows down. It is a process that is very similar to animal hibernation. The trees are not dead during this time, contrary to what it might seem.

Before all of the leaves fall in a few days, come take a walk at River Legacy to catch a glimpse of some of the beautiful tree color changes in the park and Science Center grounds.

 

What is basking?

Whenever you take a walk through the woods, you might see lots of reptiles and amphibians enjoying a sunbath. Turtles usually gather on top of a log, all lined up neatly one behind the other. Sometimes, they decide to take in the sun just off the side of a creek or river. Snakes and lizards usually like to receive the sun’s heat just off the side of a trail or on top of a log or surface. Amphibians, likewise, exhibit similar behavior.

But, have you ever wondered why these particular animals do this? What reptiles and amphibians are doing is called basking. Basking is the action of receiving warmth directly from a heat source, such as the sun or a heat lamp, by simply standing or sitting under it. Both reptiles and amphibians are ectotherms, which means that they are not able to regulate their own body temperature in the same way that other vertebrates, such as mammals or birds, can. Sometimes, this is also referred to as being “cold-blooded.” Their body temperature basically depends on their environment. Basking allows these animals to be able to obtain the energy that they need in order to move about, find food, mate, and all the other things that they need to do. This is the reason why, if a reptile or amphibian gets cold, it starts acting in a very sluggish manner.

Next time you visit River Legacy Living Science Center, take a close look at our pond. In it, you will find a small island in the middle that is a very popular spot for basking turtles. You can also search for basking lizards on any surface where the sun is hitting.

Spiders are our Friends

Spiders (Class Arachnida) are animals that, often times, get a bad reputation. Some people find them creepy, dangerous, menacing, etc. While there are some species that do present a danger to humans due to their venom (black widow, brown recluse), most spiders are beneficial and a crucial part of the ecosystem.

Spiders are carnivores whose prey includes many species of insects, thus keeping their populations in check. This is especially important for agricultural crops. Simply put, without spiders, swarms of vegetable-devouring insects would overwhelm much of the world food supply. In addition, they also eat mosquitoes and flies, which can carry diseases. On top of that, many of the things that spiders produce such as venom and silk are being used in innovative ways in the medical and engineering fields, respectively.

Here at River Legacy, there are dozens upon dozens of spider species. As you walk around our trails, take a close look at the dozens of spider webs that can be seen throughout the forest. If you see a web that looks like a funnel and it is very close to the ground, it likely was made by a grass spider (Genus Agelenopsis). Orb weavers (Family Araneidae), including the yellow garden spider (Argiope aurantia) (pictured), and wolf spiders (Family Lycosidae) are also very common.

Yellow garden spider