Lesson Plan

Lesson: Invertebrates and interdependence  

Objective: Students will demonstrate understanding of environmental/species interdependence by identifying consequences to species of removal of a particular element.

Other objectives that lesson can be used to teach: Students will demonstrate understanding of the relationship of adaptation to environment by creating an animal with adaptations to particular environmental conditions with explanation of how adaptation(s) help the creature to succeed in that particular environment.

  1. Take students to a location on creek.  Specify boundaries and have students concentrate on noticing and making note of what is before them in that specified area.
  2. Map the area to show geographic, geological, biological features of place. (shade, no shade; fast or slow running water; on water or under water; on plants or not; under rocks; eatables; oxygen; temperature…
  3. Look for animals and note what animals live where in the location; the features of the places where particular animals live.  Essential/preferred.
  4. Have students discuss what it is about the particular places where particular animals live that might attract them to those places
  5. Observe animal behavior and elements of anatomy that allow them to live in the particular environment considering the features of that environment.
  6. Activity involving consideration of changes to niche and effect on animals.
    1. Incorporate drawing, drama, story writing…
      1. Consider use Song of the Dodo.  
  7. Activity in which students develop adaptations for animals that would better suit them for a particular niche or that would allow them to adapt to changes in the environment possible, probable, or fictional.

Evaluation:  Simple evaluation: Students offer reasonable explanation as to what would happen to particular animal as a result of a particular change to environmental conditions in the niche where it resides.  

Students would show understanding of cause and effect, adaptation and environmental conditions by the products created during activities described in lesson elements 6 and 7.


  1. Use the create an animal activity, here with either specified environmental conditions or conditions students create.
  2. Deep study of animal interdependence:
  3. Carnivores and herbivores. 
  4. Storytelling, dramatic productions, art, songs; creation of guides and catalogues, etc.
  5.  Deep study of particular niches
  6. Deep study of particular animals
  7. Deep study of plant and animal interdependence
    1. Features and functions
  8. Deep study of the life of a particular tree or plant
  9. Deep study of water
    1. Water quality
    1. Flow
    1. Temperature
    1. Etc.
  10. Deep study of particular animal or class of animals
  11. Deep study of hydrology, stream biology
  12. Deep study of geology and geography as it relates to existence of niches.
  13. Study of how nutrition is derived from what particular animals eat
    1. Chemistry of foods and nutritional value particular of animals and plants and the nutritional needs of particular plants and animals
  14. Scat

This lesson can be used over the course of a day or a part of it used for a two-hour lesson or extended to include deeper and more rigorous study over the course of a week.

We can use this template to develop lessons for studying trees and plants at short or greater distances from the creek using interdependence as the theme.

Evaluation:  Students would show understanding of cause and effect, adaptation and environmental conditions by the products created 

What would happen if a feature of place were removed?

Bugs attracted to………….

Fish attracted to bugs…….

Birds and ? eat fish….

Take out element

Notes: Aquatic invertebrates are a major source of food for birds, mammals, amphibians, reptiles, fish, and other invertebrates in both aquatic and terrestrial habitats. Changes in a food source of such importance as aquatic invertebrates can have repercussions in many parts of the food web. The life cycles of aquatic invertebrates are intricately connected to land as well as water, and the majority of aquatic invertebrates spend part of their life cycle in terrestrial habitats. 

To assess the status of aquatic invertebrates in the Sierra Ne- vada, we must first consider the status of aquatic habitats. Aquatic invertebrates have complicated life cycles that are inextricably connected to both aquatic and terrestrial envi ronments (Erman 1984b). The impacts of human use of land and water are reflected in species assemblages in streams and lakes. 

stoneflies, caddisflies, alderflies, dobsonflies, snails, and clam 

Stream environments can be divided into two major habitat types:

Riffles – which are shallow rocky areas with swift currents, and

Pools – which are deeper areas often at stream bends where currents are slower, particles settle out and deposits of sediment, leaves and wood accumulate.

But as streams dry up, riffles disappear and pools can become disconnected. This reduces the richness of the stream community and results in a simpler food web. For instance, large algae-eating and filter-feeding invertebrates, which are prime food for larger animals, like birds and fish, tend to disappear.

Mountain streams can bounce back, according to the scientists. In fact, it wasn’t until several years into the drought that the team observed a precipitous decline in biodiversity and the reorganization of the food web. But increased volatility in the climate could prevent recovery even when water returns.

When flows do return, they increasingly come back in excess, in what climatologists call a whiplash. “We’re swinging from one extreme of drought to another extreme of flooding,” says Herbst, “and how this affects stream communities is not well understood.” These wide variations in flow may actually do more harm to the ecosystems than good.

Normally perennial mountain streams may become intermittent, with disconnected stretches persisting for long periods. This is standard in coastal creeks, and the wildlife there has adapted to these conditions. There’s a whole community of insects, and even some amphibians and fish, in coastal watersheds that can survive these intermittent flow regimes. But this is not common in the high Sierra Nevada.

What’s more, mountain streams play an outsized role in their watersheds. A small pond or creek at the headwaters of a river can be more critical to the resiliency of the ecosystem than miles of downstream habitat. It’s far easier for biodiversity to flow back downstream after a disturbance than to creep its way up the watershed. And if these mountain refuges run dry, there’s nothing farther upstream to reinhabit them.

“This scenario points out what you want to search for in making conservation decisions about what to protect in the mountains,” says Herbst. “In what areas might there be these potential reservoirs from which re-colonization could occur?”

Invertebrate biomass in the water was highest during the high water period and lowest in the summer and fall. Aquatic insects are the largest component of the aquatic invertebrate community, and most of them emerge as terrestrial adults in summer and fall in the Sierra Nevada, with fewer species emerging in spring and a small minority in the winter. Thus, invertebrate biomass is low then the water is low because many insects are in the terrestrial stage or are in the egg or small larval stage (N. A. Erman 1996).

Invertebrates can accommodate the natural rise and fall of floodwater by moving up with the water and outside the stream banks, by burrowing into the substrate, or by taking refuge in root wads and debris along stream edges. They return to the stream channel as the water recedes. Natural floods perform the function of flushing sediment from the stream system, which, in turn, increases pore spaces within the steam-bottom substrate and provides surface area for invertebrates to inhabit. In contrast, year-round constant flow, a condition found in some artificially managed streams, is also abnormal to invertebrate communities of the Sierra Nevada. Under constant flow, sediment is not flushed from these streams, and other poorly understood triggers to life cycle changes and in-stream migrations my not be present (Reiser, et al. 1989).

In streams, sediment accumulation depletes available habitat for invertebrates, as pore spaces in the rocky substrate are filled with sand and silt. Over time, continued sedimetation can create a cemented stream bottom with no substrate pore spaces available for invertebrate colonization.

As sediment increases, species richness, density, and biomass decrease. Sediment obstructs respiration, interferes with feeding, causes loss of habitat and habitat stability, and may alter production of invertebrate food sources (Johnson et al 1993).


Wood has been intentionally removed by state and federal agencies, including the California Conservation Corps, and my loggers and woodcutters. In addition, downed wood was retained more easily in meandering stream channels. Wood in streams serves several functions for invertebrates. It retains organic matter (leaves, sticks, and needles) that falls into the stream. It slows the water and creates pools, thereby allowing the opportunity for invertebrates to feed on organic matter, which increases the efficiency of nutrient use. Wood creates complexity of habitat by forming pools and breaking up otherwise long stream runs. And some invertebrates feed specifically on the wood or attach themselves to the wood and feed on the algae, microinvertebrates, and bacteria that grow on wood (Murphy and Meehan 1991).

Published by lafered

Retired professor of education concerned with thoughtfulness

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