When compared with moms who had difficult deliveries ending in vaginal birth, women in the study who had cesarean deliveries said they had more problems getting pregnant after the birth of their first child.
Whale is the common name for a widely distributed and diverse group of fully aquatic marine mammals. They are an informal grouping within the infraorder Cetacea, excluding dolphins and porpoises, so to zoologists the grouping is paraphyletic.dontocetes feed largely on fish and squid. A few, like the sperm whale, feed on large invertebrates, such as giant squid. Grey whales are specialized for feeding on bottom-dwelling molluscs. Male whales typically mate with multiple females every year, but females only mate every two to three years.
1 There are two suborders of whales to which all species of whales belong: toothed whales and baleen whales. 2  Toothed whales include sperm, killer, and beluga whales, and they prey on large fish in deep waters as their main source of food. Whales belong to the order cetacean, meaning they are mammals that are fully adapted to aquatic life. 2  Like dolphins and porpoises, whales are believed to have descended from land animals that returned to the water roughly 50 million years ago after living millions of years on land. 3  b.