Insects and Microorganisms

Biology study - insect leg tarsus (last sections on insect legs)

Students will collect and photograph microscopic pictures of insect legs and compare species of insects and arachnids in the design of the tarsus. The study will demonstrate the different features of the insect legs and relate the design of the leg to the insects’ environment.

Process: Collect several insect legs to study and compare the last section of the leg; this structure helps define the way the insect climbs, walks, swims or flies. You may be able to find several types of insects that have died on a window sill or in a container of water where they may have stumbled in a died. Live insects can also be collected and humanely killed in a collecting jar with some nail polish remover on cotton balls. The insects should be photographed and identified before the legs are removed and viewed under the microscope. The types of insects can include flies, ants, spiders, centipedes, beetles, butterflies, or other common insects in your local area as long as the insect is not poisonous or endangered and protected. Different insects can be saved in individual jars or containers to collect several samples from each bug, remember insects have 6 legs and spiders have 8 which can be multiple samples. Students can share samples of insects if the collected insects have multiple legs that can be removed and shared.

Concept: Studying the same portion of different species of insects will allow students to directly compare the structure to the purpose in each insect sample. The tarsus is analogous to a foot, and this portion of the insect leg will show the relationship between the structure and the purpose in each insect type studied. Insects will have distinctly different tarsus to provide ways for the insect to climb, swim, or balance depending on the environment the insect lives in.

Standards: from NYS standard http://www.nysed.gov/curriculum-instruction/science-learning-standards

P-LS1-2. Plan and conduct an investigation to determine how familiar plants and/or animals use their external parts to help them survive in the environment.

MS-LS4-2. Apply scientific ideas to construct an explanation for the anatomical similarities and differences among modern organisms and between modern and fossil organisms to infer evolutionary relationships.

MS-LS4-4. Construct an explanation based on evidence that describes how genetic variations of traits in a population increase some individuals’ probability of surviving and reproducing in a specific environment.

Examples

Many insects can be collected without catching live bugs, below is a stink bug I found on a window sill. This bug is able to climb and climb, and the tarsus on this insect has a large pair of claws to hold itself securely when it lands.

Looking at the stink bug tarsus under magnification clearly shows the strong claw.

A ladybug was also collected and the much smaller and lighter insect has a tarsus that is not as robust compared to the stink bug.

Finally we can view a very small gnat to see the tiny hooks on the ends of it's tarsus, the very light gnat still seems to need hooks similar to the stink bug and not like the lady bug.

Biology study – culture microorganisms from soil

Students will culture microorganisms from soil and leaf litter to photograph and identify different microorganisms in the culture. Students will learn about the lifecycles of the microorganisms in soil cultures and identify the roles of the different microorganisms in the culture.

Process: Collecting microorganisms and getting them to reproduce in a colony is a simple classroom or home project, using a sealed jar and leaf litter and dirt a student can cultivate a assorted sample of microorganisms in less than a week. Simply filling a mason jar or similar sealed container ½ way with grass, leaves and some soil and covering this material with clean water will allow the already present microorganisms to reproduce. After the jar is filled with the leaf litter and water, keep the sample in a warm dark place to allow the microorganisms to reproduce. Be careful to avoid using any antibacterial cleaners when washing the jar or any tools used in collecting these samples. Even a small amount of anti-bacterial soap left in the sample jar will destroy the colony. After about a week in the warmth the culture should be actively growing in a small drop of the water collected from the jar can be used to view microorganisms under the portable microscope. Use caution in opening the sample jar as there will be an odor from the decomposing leaf litter and bacteria in the jar, and remember to wash your hands when working with these samples and cultures.

Concept: These cultures will show the diverse assortment of microorganisms in our natural environment and allow students to observe several different types of single and multi-cell organisms in one sample. Students will also observe the ways these microorganisms move through the water in their environment and these different methods will help in the identification of the different creatures.

Standards: from NYS standard http://www.nysed.gov/curriculum-instruction/science-learning-standards

MS-LS4-4. Construct an explanation based on evidence that describes how genetic variations of traits in a population increase some individuals’ probability of surviving and reproducing in a specific environment.