4th Grade Waterloo Decomposers
Nature's Recyclers
Full-day trip at the Eddy Discovery Center
Observe fungus, bacteria and invertebrates at work in two types of forests, a swamp and a bog.
Unit – “Nature’s Recyclers” (Fall or Spring)
Students start learning as soon as they board the bus!
Naturalists discuss the natural systems for breaking down and recycling organic matter. Topics are broken in to three basic categories: fungi, bacteria and invertebrates (the "F.B.I."). Learning to OBSERVE and make a "best guess" or SCIENTIFIC HYPOTHESIS of what is happening in the field is an important aspect of this trip.
Fungi are all around us, breaking down decaying matter through a biochemical, enzymatic process. When there are enough resources at hand, the fungi send up fruiting bodies, commonly referred to as "mushrooms." Beneath the soil are extensive networks of "roots" called mycelium. Students will look for these thread-like structures beneath rotting logs and under leaf litter. Some mycelium networks run for many square miles.
Scientists are discovering that mycelium serve as "a vast communication network in the forests." (Michael Pollen) Watch this preview for the film Fantastic Fungi to learn more.
Some fungi glow in the dark! Their bioluminescensce is due to an enzyme called luciferase. This same, oxidative enzyme is used by fire flies to "flash" and signal for a mate.
Lichen are a dual organism composed of a fungus and an algae, living symbiotically.
Science is always evolving. A great example is the slime mold. Until recently, it was categorized as a fungi. Today, it is understood that slime molds are, in fact, soil-dwelling amoebas. In times of stress and scarce food resources, slime molds will act collectively to survive. Watch Heather Barnett's Ted Talk to learn more.
It can feel sad to see or consider dead animals. However, death is a normal and inevitable process. Decomposition of a carcass may be discussed or observed.
Turkey vultures are part of natures "clean up crew." Without them, carcasses could remain for extended periods time, decomposing slowly. Unlike most birds, vultures have a terrific sense of smell and their nose can lead them to "dinner" from over a mile away.
While vultures might not be "pretty," their role in the ecosystem should not be taken for granted. In India and Pakistan, over 95% of the vulture population has been poisoned by a drug used to treat cattle. This decline has lead to a variety of problems relating to the unconsumed carcasses, including an explosion in wild dog populations and rabies.
The hike along trails ends at a BOG, a unique ecosystem that "flips" many of the rules of decomposition that were observed at the start of the hike. Bogs are floating land masses with highly acidic water. In most circumstances, specimens decompose to the point that only the skeleton remains. In bogs, the skeleton is dissolved by the acids, but the flesh and hair are preserved through a form of pickling.
The picture above shows a few of the plants that can tolerate and grow in this highly acidic environment: tamarack, pitcher plants, and poison sumac. Naturalists will discuss other unique and interesting aspects of bogs.
Bacteria are everywhere - even inside us! - but without a microscope, we must instead look for signs of bacterial activity. When a dead animal begins to bloat, the gas inside the body cavity is a by-product of bacterial activity.
One gram of soil contains 40 million bacteria. The gut of an adult human contains six pounds of symbiotic bacteria that help break down food, regulate metabolism, and regulate moods. If a bacteria is parasitic, or harmful, antibiotics are used to combat infection.
Invertebrates are detritivores that obtain nutrients by eating detritus - decaying leaves, rotting logs, bark, etc. Examples found include slugs, centipedes, millipedes, worms, and pill bugs.
Time and weather permitting, students will visit a cemetery in the afternoon. Behavior must be respectful in deference to any visitors.Decomposition of the various grave stones will be studied, with observations on how different types of stone (limestone, sandstone, granite, marble) degrade at different rates. Decomposition is broken in to two categories: ABIOTIC: degradation via a chemical (e.g. acid rain) or physical (e.g. water, erosion) process
BIOTIC: the metabolic breakdown of materials by living organisms (e.g. lichen)