What’s the deal with fiddler crabs?


Image: CC via Wikimedia Commons

We have a new case study lesson that was published last week over at the National Center for Case Study Teaching in Science. The center is run through the University of Buffalo and is supported by the National Science Foundation. This collection is very beneficial to any science teacher, and I encourage you to look through the topics for use in your classroom.

Our case (which you can find here) deals with animal weapons, specifically extreme weapons. Our minds typically go to moose or elk antlers, but there are lots of examples from the animal world. The case looks at this from a bioenergetic perspective. For example, male moose have large antlers even though allocating resources towards growing those antlers deplete their bones in other areas by 60%. That’s incredible! It seems like their has to be a better answer than just for fighting. This case looks at fiddler crabs. Why do males have one large claw that sometimes is as big as their whole body? This large claw would seem to come with some disadvantages.

Screenshot 2016-03-10 09.06.20

This case is designed to be used in a flipped classroom. However, there are many different ways you can use it. Take it, and make it your own. Here’s the abstract:

In most animals, the drive to breed and produce offspring is strong. However, most males live their whole lives without having the chance to breed. The events leading up to mating can be very dangerous and also very costly to an individual. Some males have evolved elaborate structures, or weapons, as a result. The structures do help males in both combative situations and with attracting females, but ironically, the structures themselves come with certain costs. This flipped case study provides students with the opportunity to not only see how animal structures and functions are linked, but also to see how certain animal structures are needed and costly. There are videos that students are expected to view before the case. The case was initially designed for a second semester college general biology class for majors. However, it can also be used in non-major biology classes. Students should have some background knowledge of natural selection, specifically sexual selection as well as energetic demands of certain structures.

Organic Compound case

Mysterious Death on the Greenway
Instructors at MCC have designed a specific case study for biology students that allows the students to practice metric conversion problems, test for organic compounds, and use scientific inquiry to solve a mystery. The case is built around a deadly barred owl attack that some students observed at the greenway trail section. The story can be found here. The students complete this case in the lab. However, the data is real and was collected at the trail section. Each student group is responsible for analyzing data sets and drawing conclusions. At the end, they are required to submit a report detailing which bird they think is responsible for killing the female barred owl.

1. To learn the math behind metric conversions
2. To learn how to properly test for various organic compounds using Benedict’s reagent, Biuret reagent, Iodine solution (IKI), and Sudan III solution.
3. To learn how to generate hypotheses from data sets.
4. To learn how to design controlled experiments based on hypotheses.

The Return of Canis lupus case study

The Return of Canis lupus
Although gray wolves once freely roamed North America, the gradual loss of their habitat from westward expansion and extermination programs led to their demise in the early 20th century. Many argue that predators such as wolves benefit a functioning ecosystem. In 1995, following years of extensive planning and controversy, wolves were brought from Canada and restored to Yellowstone National Park. This case study provides students with an opportunity to integrate various abstract ecological concepts (trophic cascades, keystone species, interspecific versus intraspecific interactions) with applied ecology as they learn about the wolf reintroduction debate and the conservation of an ecosystem. As part of their case work, students formulate and present a management plan. Originally designed for a college ecology course, this case has also been successfully used with both majors and non-majors in basic biology courses. Students will need some background knowledge of community and population structure within ecosystems.

Tree ID project

Campus Tree ID
Instructors have designed a dichotomous key specific to trees on and around the Mitchell campus. During this activity, botany students have to apply the knowledge that they have learned in class to identify various species of trees and shrubs. Some of the terms that students are required to know include the following: blade, petiole, simple, compound, alternate, opposite, whirled, palmate, pinnate, and parallel. As student groups identify the species by working their way through the keys, they are also required to read about the natural history of the plants.