What's Killing the Blue Crab?


Lesson Plan Standards

1.1.1 1.2.3 1.4.2 1.4.3 1.4.6 6.2.3


Students will first complete an anticipation guide on interesting facts of the Maryland Blue Crab and the parasitic organism Hematodinium. The class will discuss their answers to hook students into the topic at hand. Students will then complete a jigsaw graphing exercise that will illustrate the population decline of MD Blue Crabs since the 1990's and how various environmental factors are related to Hematodinium outbreaks.



Students will be able to graph data collected from scientific research in order to determine how the crab population has declined and how environmental factors influence Hematodinium outbreaks.

Lesson Materials

  1. Anticipation Guide      
  2. Data for the graphs       
  3. Graph paper or Computer with MS Excel


  1. Students will complete the anticipation guide on the MD Blue Crab and Hematodinium individually by reading each statement and writing true or false in the "before" column.
  2. The teacher will hold a discussion with the class to determine the validity of each statement. The teacher can use a "thumbs-up, thumbs-down" method for quick student feedback. All statements on the anticipation guide are true.
  3. Students will be given 1 of 4 sets of data: (1 & 2) date, prevalence, water temperature, and water salinity, (3) year, prevalence, average temperature, and total precipitation, (4) year, crab harvests. The data was compiled from a series of published research articles.
  4. Display all graphs for students to see.
  5. Discuss with students the relationship between water temperature and Hematodinium, salinity and Hematodinium, salinity and total precipitation, average temperature and water temperature, and finally crab harvests and all environmental factors.
  6. Students will develop a hypothesis to answer the question "What is killing the MD Blue Crab?"



Diseases of Aquatic Organisms.pdf

Gretchen A. Messick, Jeffrey D. Shields. Epizootiology of the parasitic dinoflagellate Hematodinium sp. In the American blue crab Callinectes sapidus. Diseases of Aquatic organisms dis aquat org. vol 43; 139-152, November 14 2000.

Maryland State Standards

The student will recognize that real problems have more than one solution and decisions to accept one solution over another are made on the basis of many issues.  
The student will formulate a working hypothesis.
The student will analyze data to make predictions or decisions or to draw conclusions.
The student will use experimental data from various investigators to validate results.
The student will describe trends revealed by data.
The student will conclude that populations grow or decline due to a variety of factors. At least — Linear/exponential growth Carrying capacity/limiting factors Species specific reproductive factors (such as birth rate, fertility rate) Factors unique to the human population (medical, agricultural, cultural) Immigration/emigration Introduced species. 

The Blue Crab: Callinectes Sapidus

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pile of cooked crabs