Environmental Science: How Species Respond to Environmental Changes

Last week I shared with you three activities I shared with the Scouts. A timeline activity to introduce them to the historical events that have helped shape environmental policy in the United States, key terms bingo, and a fortune teller illustrating the metamorphosis of honey bees.

Today, my focus is on how organisms respond to changes in the environment and endangered species. These activities were selected to meet the requirements for #3a and 3e of the environmental science merit badge.

 Each Sunday through the month of September, I will post a description of the activities I coordinated and the resources I used to teach the environmental science merit badge. Today’s post is the second in the series.

Environmental Changes & How Species Respond @EvaVarga.netResponding to Environmental Changes

Ecologists do not only study organisms; they also study how organisms interact with other organisms and how they interact with the nonliving parts of their environments, like chemicals, nutrients, habitats, and so on.

The range and type of interactions that organisms can have with each other and with their environments are large and complex. Some ecologists focus on how individual organisms respond to their environment. Other ecologists are more interested in how organisms of the same species interact with each other in populations.

Still others spend their days examining how whole populations interact with other populations in a community. At the highest level, some ecologists focus on the big picture, studying the interactions between all of the living and nonliving elements in a given area, or ecosystem.

Natural Environmental Changes

Our environment is constantly changing. Natural disasters can cause drastic environmental changes and if severe enough, even mass extinctions. By examining previous natural disasters – earthquakes, tsunamis, hurricanes, and volcanoes to name just a few – and their environmental impacts we can learn what to expect in the future.

We opened our lesson with a discussion on the processes of erosion. The Scouts were asked to submit to me photographs of areas where they had observed erosion and to describe what elements contributed to the process. Here are a few of the photos they submitted:

Why Should We Care?

So, why should we care about ecology? For some communities changes to climate are causing longer droughts, more severe floods, and harsher environments. Let’s put it into perspective with just one case study made famous by John Steinbeck’s novel, Cannery Row.

Every year, more than 92 million tons of ocean life (like fish, aquatic plants, and so on) are “harvested” from around the world for human consumption. Billions of people rely on these harvests to sustain life – either for food directly or for their livelihood. A poor understanding of marine ecology can result in disaster.

One of the most well-known of these disasters occurred off of the coast of California in Monterey Bay in the mid-1950s. At the time, this bay was one of the most productive fisheries in the world, particularly sardines. However, before 1960, harvests had plummeted, and, by 1973, the last sardine cannery in Monterey closed its doors forever.

Unfortunately, the fishing industry had not applied common ecological sense in their decisions. Sardines were removed from the bay faster than they could reproduce, resulting in a population crash and the end of an economy.

How Do Caterpillars Respond to Stimuli?

Rainforest CaterpillarsBefore my children were born, I volunteered on an Earthwatch expedition to study Rainforest Caterpillars. It was one of the most memorable experiences of my life – particularly when I consider the impact it had on my classroom teaching strategies. While the focus of our study was on Parasitism in Caterpillars, what stands out to me about this experience was the real-time observations we were able to make in the field – recording how the caterpillars responded to mechanical stimuli.

Essentially, we would gently pet them with a small paint brush and then pinch them carefully with a pair of tweezers (enough to get a reaction but not to harm).  We would then record their behavior or reaction to the stimuli.

We did this to get a general idea of how the different species would defend themselves and observed a wide variety of behaviors including thrashing about, rearing up and attempting to bite the attacker (that would be us), as well as and most amusing, kicking frass at us.

If you have caterpillars in your local area, give this a try. How do your local species respond to the same stimuli described above?

How Do Aquatic Organisms Respond to Stimuli?

Materials

  • Living specimen of planktonic aquatic life
  • Droppers
  • Vinegar
  • Caffeinated and decaffeinated coffee
  • Sugar
  • Specimen pipettes
  • Compound micropscope
  • Salt crystals
  • Microscope slides and coverslips
  • Cotton fibers

Procedure

  1. Using a specimen pipette, remove a drop from the collected specimen.
  2. Place culture on the microscope slide and cover. Focus microscope to locate organism.
  3. After first observing normal activity, introduce artificial stimuli so the the response can be observed. Record behavior observations on a chart in a lab notebook.
  4. Prepare a new culture specimen if necessary; repeat steps 1-3.
  5. Carefully place a small salt crystal near some of the swimming organisms. Observe and record their response.
  6. Continue to add each stimuli, observing and recording the behavior each time.
  7. Observe movement. Are new structures visible on the organism? Has movement increased or decreased?

Alternatively, you might consider the Goldfish Lab I shared sometime ago.

Environmental Science Endangered SpeciesEnvironmental Changes & Endangered Species

In addition to the activities and discussion described above, Scouts were expected to write a 100 word (minimum) report an an endangered species of their choice. They were then asked to present what they had learned with the group. In this way, we would have a broader perspective and learn how environmental changes have effected a variety of species.


Join me next week as we explore topics related to pollution and acid rain.

A Surprise Cross Pollination Experiment

We attended Norway Day in May and enjoyed a variety of activities and cultural presentations.  One of the activities the kids took part in was painting a flower pot and planting a Petunia that they could take home.  Sweetie selected a white Petunia and Buddy, a deep purple (sadly I wasn’t able to get a photo of Buddy’s – he wasn’t happy with his painting and didn’t want me to take a picture).

petunia cross pollination

We brought the flowers home and enjoyed their blooms indoors for a short time.   Frustrated with the dirt spilling on my counter, I suggested the kids put their pots on the front porch.  Sweetie was careful to water hers regularly (Buddy, not so much) and as could be expected, hers bloomed again.  To our surprise, however, her blossoms were no longer white but striped with purple!  “Mom!  Look at my Petunia!  I think bees must have visited both mine and Buddy’s!  Isn’t this cool?”

petunia nature study

Cross Pollination

Petunias are flowering plants that belong to the Solanaceae family and are hardy to climates within planting zones 10 to 11. Even though these sun-loving plants grow flowers that contain both the male and female reproductive organs, also known as the stamen and pistil, they won’t self-pollinate. Pollination thereby must occur through insects or wind to transfer pollen from one flower to another.  You can also play the role of the insect and transfer pollen yourself.

  1. Select a healthy, freshly bloomed petunia plant. Lightly swipe your fingernail over the yellow pollen on the anthers inside one of the plant’s flowers — if the pollen sticks to your nail, the flower is ready to pollinate other flowers
  2. Look for the stigma that’s sticking out in the center of a petunia flower that you want to pollinate. Lightly touch it with your finger. If it’s glistening and sticky to the touch, the flowers are ready for pollination.
  3. Moisten a cotton ball with rubbing alcohol and swipe it over a pair of tweezers to sterilize them. Allow the tweezers to air-dry.
  4. Hold onto the parent petunia flower with your nondominant hand. Use the tweezers to grasp the base of the filament inside the flower. The filament is the thin stem that holds up the anther with pollen. Pull upward to remove the filament from the flower with the anther and pollen intact.
  5. Rub the anther over the top of the stigma of the receiving petunia flower so the yellow pollen adheres to it. Pollinate as many flowers as you like in this manner.
  • Alternatively to removing the stamen, you can swipe a small paintbrush over the pollen from the parent flower and brush this pollen on the stigma of the receiving plant.

petunia pollination

When the pollen from one flower is carried to the stigma of another flower they combine their genetic information (RNA) and their seeds should produce a hybrid of the 2 original plants.  The hybrid may not have obvious changes in its appearance because plants carry similar genes. If you want only plants with the same characteristics from year to year then simply save the seeds from your favorite blooms and plant the seeds next year.

hybrid  A cross between two parent plants that are from the same species but don’t look exactly like each other.

This discovery – while unplanned – was a fascinating opportunity for us to further explore the concept of pollination.  While some plants, such as peas, self-pollinate very well; others, such as Petunias, are structured in such a way as to assure cross-pollination.  If your children are full of questions and interested in further exploring cross-pollination, encourage them to set up an experiment to answer their questions.  For example:

Experiment :: What would happen if flowers that usually cross-pollinate were self-pollinated instead?

For this experiment consider using Wisconsin Fast Plants which carry out their entire life cycle in less than a month if grown under constant lighting.  The flowers of Fast Plants have long pistils and short stamens, which makes it difficult, if not impossible, for them to self-pollinate.  Once the plants set seed, wait for the fruits to ripen, then count the seeds in the fruits and examine their quality. Which plants set the most seeds: the cross-pollinated plants or the self-pollinated plants? Was there any difference in the size and development of the seeds? Try germinating the seeds from each set of plants, either on moist soil or moist paper towels. Is there a difference in germination rates?

Submitted to the Outdoor Hour Challenge Blog Carnival at Handbook of Nature Study.

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