Egg Survivorship Game Overview

No Instructions Necessary. Let's Play!

Background and Instructions to Follow:

Background on Terrapins:

Diamondback terrapins are turtles that inhabit estuaries along the east and Gulf coasts of the United States. They range from Cape Cod, Massachusetts to northern Mexico. Terrapins were harvested in the late 1800’s through the early 1900’s as a food source with a high demand leading to reductions in their populations across their range. In the 1930’s, terrapins became less desirable food sources and populations increased in areas with good habitat, but not much is known about populations in certain areas. What make terrapins so interesting are their markings, which are highly variable and prominent. Reasons for the variation include genetic diversity and some variations in their patterns could be linked to environmental conditions.

Female terrapins grow larger than males and some females could be as large as 23 cm (9 inches) in carapace length. Males are smaller and may reach sizes of 15 – 18 cm (6 or 7 inches) as adults. In terms of maturation, females in New Jersey can mature in 7 – 9 years, while males can mature in 3 – 5 years. Females will nest on bay beach areas adjacent to marshes where they can deposit up to 18 eggs (called a clutch of eggs). The mean clutch size at Sedge Island, Barnegat Bay, New Jersey is around 12 eggs (Wnek, 2006 and 2007). The nesting female terrapin will dig a nest, deposit eggs and immediately return to the water. The depth of the nest depends on the compaction of soil and depth at which the female can dig. Eggs are deposited as deep as 21 cm (9 inches). Temperature of the nest influences the gender of terrapins; Eggs incubated at temperatures above 28 Celsius will mostly develop as female and below this temperature, male.

Eggs are somewhat soft, considered cleidoic, which allows for gas exchange during incubation. After approximately two months, terrapins emerge from their nest and make their way to vegetation and nearby marshes. From this point, little is known about their growth and life stage, but we know they live and feed within marsh habitats. Some of their food resources include snails, shrimp, crabs, and fish to name a few.

The goal of this activity is to learn about the basic life history characteristics of the diamondback terrapin. You will be assigned a specific egg number. Although there may be 4 – 18 eggs in a nest, we have an activity for 50 and 100 eggs that would be from multiple nests on the North Sedge Island, Barnegat Bay, New Jersey. The goal is to successfully hatch, emerge from the nest, and become an adult terrapin. Gender will not be addressed at this point.

A general PowerPoint Overview can be downloaded
All we need is 100 simulated eggs and let's go!

Instructions

Items recommended for the activity:

You can use 100 ping pong balls or plastic practice golf balls and number them from 1 to 100 using a permanent marker. These represent the egg numbers and types

Depending on the number students in the class they could be divided in groups. For example, with a class of 32 students, there can be 8 groups of 4 students. Each of the students in the group would get 3 numbered eggs at random. The group of 4 students with a total of 12 eggs would represent an entire clutch of eggs. The remaining eggs can be distributed at random to individuals in different groups so that some of the groups have 13 eggs total and four individuals have 4 eggs.

At the end of the activity, the surviving individual within the clutch is the one remaining!

If you cannot get plastic balls to simulate eggs then number pieces of paper. Remember, there are typically 9 – 16 eggs at Sedge Island, Barnegat Bay, New Jersey. You can divide the groups up accordingly to meet the requirements of the clutch and class sizes.
We have the simulated eggs so let's go!

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