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Diamondback Terrapin Curriculum Guide Educator Background Materials A) Physical Characteristics 1) Northern diamondback terrapins are most easily identified by the diamond-shaped, concentric rings on their scutes (large thin scales) of their carapace (top shell). 2) The carapace can range from light brown to black and may even have a bluish gray appearance. 3) The skin of the diamondback terrapin is often a bluish gray with black speckles, dots, or blotches. Some skins are nearly black or gray and without spots. Like the fingerprints of humans, no two terrapins’ skins are alike. 4) The plastron (bottom shell) may be yellow or olive in color. Suggested Retention Question: What is the best way to identify a Northern diamondback terrapin? B) Gender 1) Females: Female terrapins are larger than males, reaching up to 9 inches in carapace length. They have larger, wider, heads and taller, rounded shells. Females reach sexual maturity around 12 years of age. 2) Males: Males seldom reach 6 inches in length, but have larger, longer tails. Males have smaller heads and flatter shells. Males reach sexual maturity at 4-5 years. 3) Gender Determination Gender is determined in terrapins by the temperature of their nest. 82 degrees or less will produce mostly male hatchlings. 86 degrees or more will produce mostly female hatchlings. Critical thinking question: How could global warming threaten the diamondback terrapin? C) Young An average nest contains 8-12 eggs, which are usually laid between late May and July. Females lay their eggs in sandy area, particularly sand dunes. The mother leaves the eggs alone. Quarter sized hatchlings emerge 7-10 weeks later. D) Diet Terrapin are carnivores and sometimes carrion feeders (scavengers). They eat crabs, shrimp, snails, clams, worms, and small fish. E) Habitat Requirements The terrapin is the only turtle species in the world that relies on estuaries (where fresh and salt water mix) for its entire life. In America they are the only turtle found regularly in estuaries. As reptiles, diamondbacks are cold blooded and need to breathe air. To warm up these turtles need access to basking areas (places for sunbathing). They need cool water or shade to cool down. Our local terrapin, the northern diamondback terrapin, ranges from Cape Cod to Cape Hatteras. While different subspecies of terrapin inhabit coastal areas from Cape Cod to Corpus Christi, this long stretch of bays, sounds, salt marshes, and other brackish environments is very thin and subject to tremendous disruption from development, storms, and sea level rise. F) Threats Northern diamondback terrapins face many threats throughout their range. Loss of nesting sites- Hardened shore like bulkheads and rip rap can make it difficult or impossible for females to reach sandy nesting sites in some areas. Road mortality – While terrapins live in the bays, the females often cross roads in search of sand dunes. During this time they are susceptible to being killed by vehicles. Sometimes the eggs of a vehicle struck female can be saved. But females only reproduce after turning 12, and while they can reproduce for 20 years few of their young survive and so the loss of female terrapins is of great concern. Loss of wetland habitat- All terrapin species rely on a variety of food sources found in wetlands. Crab Traps- Since terrapin need to breathe air they often die if they get stuck in a crab trap. Terrapin will enter a crab trap in search of the bait intended for crabs, or for the crabs themselves. Devices known as BRDs (Bycatch Reduction Devices) or TEDs (Terrapin Excluder Devices) can be easily installed on crab traps to reduce this hazard. Not only are the devices extremely effective at excluding terrapin, but since crabs often avoid crap traps with terrapin in them, they increase a crabbers catch. The Maryland Coastal Bays Program has a limited supply for the public. Ghost traps- submerged crab traps that are lost, discarded, or otherwise abandoned are known as “ghost traps” and threaten terrapins who may enter them and then be unable to escape. Commercial Harvesting- Harvesting of terrapin is now illegal in Maryland and most other states but was historically a very detrimental to terrapin populations. Predation- Diamondback terrapin are susceptible to predation during the first year of their lives. Their eggs and hatchlings are an important food source to many species. However, in some areas terrapin suffer from what are known as human subsidized predators. These are predators whose populations increase because of human activities. For example many coastal resort areas have abnormally high populations of raccoons, skunks, fox, and seagulls because these species are successful at scavenging food from trashcans, dumpsters, beaches and boardwalks. These scavenging animals are also capable of hunting and will readily gobble up terrapin as they search beaches for food. Similarly outdoor cats and loose dogs may try to eat, or play with (which will likely kill) young terrapin. Critical thinking: Which of these do you think are likely to be especially bad in Maryland’s Coastal Bays? H) Lifespan: Terrapin may live up to 50 years in the right environment. Terrapins do not migrate but rather go torpid, or hibernate in the winter. Elementary lesson Themes: Physical characteristics of terrapin Habitat requirements of terrapin General importance of wetlands Terrapin place in the food web How students can play a role in terrapin protection Elementary Lesson 1 Description: This lesson will demonstrate the importance of wetlands by relating the importance of its habitat function for the diamondback terrapin. Students will comprehend four main components of habitat; food, water, shelter, space. Students will illustrate an ideal terrapin habitat and then use overhead transparency sheets to demonstrate the potential effects of different land use practices on said habitat. Time: 1 hour Materials: Activity 1 - Wetland metaphors: Sponge, mixer, strainer, coffee filter, cereal, soap, bag. Activity 2 – Drawing activity: Large sheets of paper (4), crayons/colored pencils, overhead transparencies (4), tape or magnets, field guides or fact sheets. Introduction (10 min): Divide students into groups. Distribute field guides or fact sheets and have each group select 2-3 facts about diamondbacks that can be used to lead a class discussion. With the provided background information, educators will lead a group discussion to touch on the physical characteristics of a terrapin, their habitat requirements, diet and nesting habits, and threats facing them as an individual species. Demonstration (5 min): Instructor may have to review definition of ‘metaphor’ with students. Have volunteers reach into a bag and pull out an item. Then the student, with the help of his/her classmates, will explain how this item represents the functions of a wetland. (E.g. “A wetland is like a sponge because….” A) Sponge – Absorbs runoff and storm surges. Retains Moisture. B) Mixer- Mixes nutrients and oxygen into the water. C)Strainer – strains pollution, sediment from the water. D) Cereal- Wetlands are a source of nutrient rich food. (Hummus) E) Soap – Cleans the water F) Coffee filter – strains small impurities from the water. A. Divide the class into groups. Provide groups with a sheet of paper and markers/crayons/colored pencils. The paper should have a line delineating the shoreline and it should match up with other pieces of paper so that students can place them side by side and have a group shoreline. B. Ask students to think about the previous activity and create drawings of ideal terrapin habitat based on what they have already learned. Photographs of ideal habitat may be helpful. C. Give the students 15-20 minutes to create their habitat and then have them line up their drawings on the blackboard to create a shoreline. Each group selects a representative to explain their habitat. D. Now allow students to ‘develop’ a piece of land by drawing either a single family home, apartment building, farm, restaurant, or retail development on a transparency. Overlay the transparencies on the shoreline to allow students to visualize how development impacts terrapin. E. Lead students in a discussion about how each type of development will affect the terrapin. Ask them to think of ways people can live harmoniously with our state reptile. Reflection (10 min) A. Review components of a habitat: food, water, shelter, space. B. Review the specific needs of a terrapin population. C. Discuss ways people their age can protect diamondback terrapin. Ex. Pollution and litter reduction, volunteer in shoreline restoration projects, install TEDs, don’t support human subsidized predators.
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