Chelonlans: Reptiles with Shells Turtles, Tortolses, and Terrapins More than 250 species ofturtles, tortoises, and terrapins inhabit Earth's deserts, woodlands, freshwater ponds streams, marshes, and oceans. Scientists call these reptiles with shells chelonians, and evidence suggests that these creatures have changed very little in the last 200 million years. Recognizing a member of the Chelonia order is easy for many people, but classifying the animal as a turtle or a tortoise can be tricky. Some experts say that a chelonian that lives mostly in the water is a turtle.while chelonians that live on land are tortoises. However, it isn't always that simple. For example. box turtles are primarily land animals, but they're still called turtles. In parts of the United States, some turtles are known as terrapins, a name that comes from an American Indian word meaning "little turtle."Terrapins live in or near brackish (slightly salty) water along the Atlantic and Gulf coasts. Wherever they live, all female turtles, tortoises, and terrapins lay their eggs on land. 3 Achelonian's shell is made of flat bones that fit neatly together, and the shell doesn't come off -It's part of the creature'skeleton. A turtle's backbone and ribs blend into the upper shell, called the carapace. The lower shell is called the plastron. The upper and lower shells are connected at the sides. 4 A layer of skin covers the bones of the carapace. In most chelonians.this skin produces large scales called scutes. In a few species, the skin forms a tough, leathery layer over the shell. Some chelonians can pull their heads and feet into the she You might hear a hissing sound as it retracts its head and legs: the animal is expelling air so it can fit inside. The Threat of Extinction Because chelonians have been around for so long.it might be surprising to learn that some species are endangered. Although otters, raccoons. crocodiles, snakes, bears, and large birds can feed on chelonians, that's not what has brought some turtles and tortoises to the edge of extinction . The greatest threat usually comes from human beings. 6 In many areas of the world, the nesting sites and habitats of chelonians This sentence is from the passage. "Because chelonians have been around for so long.it might be surprising to learn that some species are endangered." (Paragraph 5) How does paragraph 7 help to further develop this idea? 1. It proposes solutions to the multiple human threats that turtles face. 2. It describes how little the turtle species has changed over the centuries 3. It compares and contrasts the impact of human and animal groups on turtles. 4. It explains why humans should be concerned about saving the turtle population.