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.
Despite living in the water, whales breathe air. And like humans, they are warm-blooded mammals who nurse their young. A thick layer of fat called blubber insulates them from cold ocean waters. Some whales are known as baleen whales including blue, right, bowhead, sei and gray whales. This refers to the fact that they have special bristle-like structures in their mouths (called baleen) that strains food from the water.