Who loves water? Marine Mammals!
Marine mammals are warm-blooded creatures that live in the ocean all the time or for large amounts of time. More importantly, these animals rely on the ocean for their main food sources. There are many different types of marine mammals, from whales to polar bears. Sadly, many of these wonderful species are being threatened due to a number of man-made causes. By learning more about them, we can all help to educate others and take steps towards protecting marine mammals.
Marine mammals are generally divided into four main categories: cetaceans, pinnipeds, sirenians, and fissipeds. Cetaceans resemble extremely large fish, which makes them very easily recognizable. They include dolphins, porpoises, and whales. Cetaceans typically have flippers near the front of their bodies and depend on thick blubber layers to keep their core temperatures stable. Many cetaceans have been known to possess remarkably high levels of intelligence. Pinnipeds are marine mammals that tend to be semi-aquatic. They have sleek bodies and use two sets of wide flippers to swim and move on land. Sea lions, seals, and walruses are prime examples of pinnipeds. Sirenians spend their entire lives underwater, but unlike many other marine mammals, they are herbivorous. Dugongs and manatees are the best-known types. Although they appear very heavy and awkward due to their large size, sirenians are able to move quite adeptly in the water. Finally, fissipeds are creatures that are carnivores. They are quite distinctive by the simple fact that they have separated digits and fur. They include polar bears and a few certain types of otters. They spend some time on land and often dive into the ocean for food.
Diversity and Habitat
Within each category of marine mammals are many different sub-species. They live all around the world, but their concentrations are higher in some areas than others. This is mainly due to the availability of food sources and the environment. Areas with high amounts of marine mammal life generally lie roughly halfway between the Equator and each of the North and South Poles, where there are plenty of feeding opportunities.
Anatomy and Physiology of Marine Mammals
Marine mammals developed in various different ways to adapt to their different habitats. One key requirement is the need to stay warm while in the water. The main two features that fulfill this requirement are blubber and thick coats of fur. The body shapes, which are often elongated, also help to minimize any heat loss. Marine mammals have incredibly strong fins, flippers, or paws to help them swim very long distances through strong ocean currents. Since they need to be strong swimmers to find food, they are also able to hold their breath for long periods of time before surfacing. Finally, marine mammals have unique ways of hearing underwater, such as echolocation used by dolphins and whales. This enables them to stay underwater and be alert to any oncoming predators.
There are many reasons that have caused marine mammals to become threatened, or in some cases, even endangered. Humans are primarily to blame for most of these cases. Over a long period of time, marine mammals have been hunted for fur, food, blubber, and other parts. Although there are regulations in place, illegal hunting still continues. Even fisheries that do not intend on capturing marine mammals end up doing so accidentally due to entanglements in nets, fishing lines and traps. On several occasions, marine mammals have suffered grave injuries or fatalities after being hit by boats. On another level, escalating pollution levels make their current homes uninhabitable or cause sickness, deformations, genetic defects, and death. Beyond this, pollution also leads to climate change, which in turn alters the temperatures of the ecosystem and changes the animals' behavior. Climate change also contributes heavily to habitat loss, as seen with rapidly melting glaciers and dwindling food sources.