Work Text:
Unit III. The paragraph
Cetaceans
Cetaceans are an infraorder of mammals completely adapted to aquatic life and composed of about 80 different species, among which some of the most recognized are blue whales, dolphins, and orcas. Many species of cetaceans use Venezuelan waters to hunt for food, reproduce, or raise their young, but the most iconic species is the river dolphin or tonina, as it is popularly known, which inhabits the Amazon and Orinoco river basins. Within the infraorder of cetaceans, there are two large groups, differentiated by the jaw, which conditions their type of feeding: the toothed cetaceans, or odontocetes, and the bearded cetaceans, or mysticetids. Toothed cetaceans, as their name indicates, are those that have teeth in their jaw, among which we can find dolphins, orcas, and sperm whales, on the other hand, bearded cetaceans are those that have baleen in their jaw, which are filamentous structures whose function is usually to filter the water to capture prey such as fish, krill and plankton, among which we can find blue whales, gray whales and humpback whales. Feeding habits vary among the different species of cetaceans, but all animals belonging to this infraorder are carnivores that feed on prey such as fish, squid, octopus, or krill. Cetaceans are very intelligent animals, that use many strategies to hunt, such as dolphins, which use echolocation and their speed to hunt fish, orcas, which organize themselves into groups to hunt a wide variety of prey, their favorite being seals, and humpback whales, which create curtains of air bubbles underwater, trapping shoals of fish inside and eating a large amount of them in a single bite. Some cetacean species such as orcas are very social, living in family groups of up to 40 individuals, with the oldest and wisest female as the leader, while other species, such as river dolphins, prefer a solitary life and only come together during the mating season. The great variety in shapes, sizes, and habits of cetaceans is one more proof of the wonderful diversity that we can find in the oceans of our planet, full of amazing animals and mysteries to discover, because although they only make up a small percentage of the great variety of marine life, we can find cetaceans in all the oceans of the world, from the warm waters near the equator to the icy waters of the poles, cetaceans are certainly wonderful creatures