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b'This week we return to the sea to learn about some marine reptiles, both living and extinct!\\n\\nA marine iguana, eatin:\\n\\n\\n\\nAnother marine iguana, swimmin:\\n\\n\\n\\nMaybe Darwin was right about the marine iguana looking like imps of darkness:\\n\\n\\n\\nA mosasaurus skeleton:\\n\\n\\n\\nA plesiosaur skeleton:\\n\\n\\n\\nThalattosaurs:\\n\\n\\n\\nShow transcript:\\n\\nWelcome to Strange Animals Podcast. I\\u2019m your host, Kate Shaw.\\n\\nIt\\u2019s been a while since we had an episode about the ocean, and I thought it would be interesting to learn about reptiles that evolved to live in a marine environment. Some marine reptiles we\\u2019ve already covered in previous episodes, including saltwater crocodiles, sea turtles, and sea snakes. But we haven\\u2019t talked much about extinct marine reptiles, and I don\\u2019t think we\\u2019ve ever had an episode about the marine iguana.\\n\\nThe marine iguana is only found on the Galapagos Islands. It eats seaweed and algae that grow in shallow water around the islands, so it swims and dives to find its food. It\\u2019s a large, strong iguana that can grow up to five feet long, or 1.5 meters, with short legs, a short snout, and a row of spines along its back. It\\u2019s black or gray in color, which absorbs heat from the sun and keeps the iguana warmer. Many have colorful markings, especially males during the breeding season. The markings might be red or pink, blue-green, yellow, or off-white, depending on subspecies. Some researchers think the kinds of algae eaten by the various subspecies of marine iguana also contributes to the colors of their markings. Males are larger than females.\\n\\nThe marine iguana is well adapted to swimming, although it\\u2019s not a fast swimmer. It uses its flattened tail and partially webbed toes to propel itself through the water, and the spines on its back keep it stable in the water. It has long claws that it uses to hold onto rocks to keep from being swept away. Newly hatched babies can swim immediately, but they stay out of the water whenever possible until they\\u2019re at least a year or two old. The water around the islands is cold, so the marine iguana will forage in the water for a short time, then come back on land to bask in the sun and warm up.\\n\\nOnly the biggest marine iguanas, mostly adult males, will dive for their food. Females and smaller males usually stay in shallow water, especially at low tide when the algae is easier to reach. A marine iguana can dive up to almost 100 feet, or 30 meters, and stay underwater for half an hour. During bad weather, the iguanas stay on shore, often gathered together to conserve body heat.\\n\\nResearchers used to think the marine iguana evolved from land iguanas that were swept from Central or South America by storms and floated to the Galapagos islands on rafts of vegetation. Then genetic studies showed that the marine iguana started evolving separately from land iguanas around 8 to 10 million years ago. The Galapagos islands are of varying ages, formed by volcanic activity, but the oldest is only about 3.2 million years old. So obviously the two groups of iguana were separated long before the Galapagos formed. Researchers then speculated that there may have been other, older islands in the Galapagos or nearby that are now submerged, which were where the marine iguanas first started to evolve separately from land iguanas. Then new genetic studies indicated that marine and land iguanas actually separated about 4.5 million years ago, which is not that much of a difference from the oldest islands of the Galapagos, so researchers are back to the original hypothesis. As I\\u2019ve said before, science isn\\u2019t wrong or right, scientists learn new things and adapt their theories to account for the new information.\\n\\nFor instance, at the moment researchers aren\\u2019t sure how marine iguanas shrink during years when weather conditions keep them from finding as much food as they need. I don\\u2019t mean they lose weight, I mean they actually shrink. Results of a study published in the journal Nature say m...'