Scientific Name: Mustelidae The charismatic otter, a member of the weasel family, is found on every continent except Australia and Antarctica. Most are small, with short ears and noses, elongated bodies, long tails, and soft, dense fur. There are 13 species in total, ranging from the small-clawed otter to the giant otter. Though most live in freshwater rivers, lakes, and wetlands, the sea otter and the smaller marine otter are found in the Pacific Ocean. Habitat and youngWebbed feet and powerful tails, which act like rudders, make otters strong swimmers. Their nostrils and ears close to keep water out, and waterproof fur keeps them warm. They must carefully groom their fur and furry undercoat to keep them clean and sealed off to water, because they’re not covered in a fatty layer like other seagoing creatures. Otters have the densest fur of any animal—as many as a million hairs per square inch in places. Otters also have particularly stinky poop, which even has its own name: spraints. It’s thought to get its special odor, which some scientists describe as smelling like violets, from the seafood diet otters eat. Most otter species come ashore to give birth in dens, which sometimes have been used by other animals such as beavers. Sea otters are the exception, giving birth in the water. Baby otters, called pups or kittens, stay with their mothers until they’re up to a year old, or until she has another litter. River otters don’t breed until they’re at least five years old. Amazing behaviorsAll otters are expert hunters that eat fish, crustaceans, and other critters. Sea otters have an ingenious method to open shellfish. A sea otter will float on its back, place a rock on its chest, then smash the mollusk down on it until it breaks open. When it’s time to nap, sea otters entangle themselves in kelp so they don’t float away. They also sometimes intertwine their feet with another sea otter, so that they stay together. River otters are especially playful, gamboling on land and splashing into rivers and streams. They learn to swim when they are about two months old, when their mother pushes them into the water. ThreatsOtters and their mustelid relatives were once hunted extensively for their fur, many to the point of near extinction. Despite regulations designed to protect them, many species remain at risk from pollution and habitat loss. The sea otter is listed as endangered on the IUCN Red List, pressured by pollution, pesticides, and conflicts with fishermen who kill them for eating their fish. Asian otter species also face threats from the illegal pet trade. Filming Otters In Brazil's Pantanal, we get the rare opportunity to film a family of rare and elusive giant otters. By Kaylee Mulhollen Sea otters, or Enhydra Lutris, are the second smallest marine mammal but heaviest of the otters. They reach a maximum weight of forty-five kilograms (kg), although their averages are below this with males weighing 28.3 kg and females 21.1 kg. Sea otters are dark brown in color, with a yellow and brown head and neck. In elder animals, their heads appear gray, which has led to the referral as “the old man of the sea.” These remarkable creatures can live out their entire lives without coming to land (Love, 1). They are the only mammals, other than primates, that use tools in the pursuit of food. Sea otters feed upon invertebrates, and will use stones to dislodge their shellfish prey. Sadly, there are many threats affecting sea otters leading to their decreased population. Since they are a keystone species, their role in the environment has a greater effect than other species. The worldwide population of sea otters was once estimated to be numbered between several hundred thousand to one million before nearly being hunted to extinction. Today, these numbers have slowly recovered but are not where they used to be (Defenders of the Wildlife). Factors such as natural predators, oil spills, as well as other human interactions are leading to the endangerment of sea otters. Sea otters encounter many natural predators; some on land, others in the sea. Humans are the biggest threat to the otter, hunting them until their numbers are drastically low. Some fishermen view otters as competition since they eat many of the shellfish humans enjoy such as urchins, lobsters, and crabs. During the eighteenth century, sea otters were hunted to the verge of extinction for their fur; a commodity the Russians referred to as “soft gold.” Other human interactions may also lead to habitat degradation due to the creation of pollutants on land. Run-off enters the waters and contaminates their habitat, food sources, and can even harm them directly. According to Defenders of the Wildlife, in California, parasites and infectious diseases cause more than forty percent of sea otter deaths. Scientists have also reported that man-made chemicals are at some of the highest levels ever seen in marine animals. Other predators to sea otters live in the sea with them. Scientists are unsure why, but shark attacks have increased causing a decrease in northern and southern populations. Sea otters are not typically what sharks prey upon, leading to many half-eaten otters found around shore. Other sea predators include killer whales and sea lions. For example, the Alaskan otter is susceptible to killer whales. Approximately 40,000 are consumed annually in this area shown in the map in figure 1 (“Friends of the Sea Otter”). There is not much we can do to prevent the natural food chain, but if humans take precautions to prevent sea otter endangerment, we may see their population numbers greatly increase.A second threat to sea otters are oil spills. Oil caused from offshore drilling, another human interaction, enters their habitat and produces an immense threat to the otters. Sea otters do not have a layer of blubber like most marine animals but instead have the densest fur in the animal kingdom to keep them warm. Oil causes their fur to mat, preventing the insulation of their bodies as seen in figure 2. Without this insulation, sea otters can die from hypothermia. Severe damage of otter’s lungs and eyes, as well as kidney and liver failure can be caused by the toxicity of the oil. The accumulation of only 200 parts per million of toxic hydrocarbons in a sea otter’s body tissues can lead to death. One example of the impact the spills have on sea otters is the Exxon Valdez oil spill in Alaska’s Prince William Sound (figure 3). On March 24, 1989, the 30,000-ton tanker swerved to avoid ice and in result poured eleven million gallons of crude oil into the sea. Within a month, the oil affected 1,244 miles of shoreline along the Alaskan peninsula. The Prince William Sound was home to the healthiest populations of sea otters in the world, so any otters in this area were at risk. By September, 1,016 sea otters as well as 37,000 birds of seventy-four different species had been found dead (Love, 132). John Love describes the devastating findings in his book Sea Otters, “A thousand sea otter carcasses have been picked up- most of them almost unidentifiable lumps of black, congealed oil. Many more may never have been found.” Arguments have begun on the true toll of the spill, but scientists agree the actual death toll was between 100,000 and 300,000, leading to the Exxon Valdez oil spill being described as the greatest environmental disaster in history. “Contrary to claims of rapid recovery and limited long-term effects, ample evidence accumulated in the decades since the spill has demonstrated that not all injured species and ecosystems recovered quickly,” writes James Bodkin. The ‘lucky’ otters that survive the spills are taken to rescue centers, where only half of the treated otters survive. The stress of being handled can worsen the otter’s symptoms caused from the spill. Those who do survive may have permanent internal damage, meaning they may never be able to return to the wild and must live the rest of their lives in captivity. According to Love, of the sea otters who recovered, only forty-five returned to the wild, each with radio tags to monitor their fate. Oil spills will continue to remain a threat for sea otters as well as many other species until offshore drilling around their habitats end and companies learn from the Exxon, as well as other, incidents. In the 1970s, conservation of otters became an issue of importance that remains with us today. According to Paul Chanin in his book The Natural History of Otters, there are four main methods available to conservationists: legislation, habitat protection, education, and captive breeding. ‘Save the Otter’ was a campaign by Friends of the Earth with the objective to add otters to the Conservation of Wild Creatures and Wild Plants Act of 1975. By 1978, catching or killing an otter or attempting to do so in England or Wales became illegal (Chanin, 162). Controversy over legally protecting otters in the 1970s brought the species to the publics’ attention, which helped conservation organizations by generating a great deal of public sympathy. While legal protection is useful, habitat protection is more important when helping endangered otters. Setting aside large areas and providing nature reserves could be useful to provide otters with a safe refuge unless or until their wild habitats are suitable. A third important task in conservation is educating the public on the species. To truly stop the degradation of otters’ habitats, the public must be informed of their consequences and be persuaded to act differently. The fourth and final important task in conservation is captive breeding. “So far only a very small number of species have been returned to a truly wild state in sufficient numbers to re-establish a viable population, for example, the Hawaiian goose or ne-ne and the European bison,” writes Chanin. Captive breeding is an important aspect of conservation with the goal of supplementing populations or re-introducing those that have become extinct. In the case of sea otters, captive breeding may be a very useful tool to increase their population. By themselves, none of these methods have the ability to ‘save’ the sea otter; however, together, we may see significant improvement within the species. Factors such as natural predators, oil spills, as well as other human interactions will continue to lead to the endangerment of sea otters unless sufficient work is done. Through the use of legislation, habitat protection, education, and captive breeding, sea otters may one day return to the abundant population they once were. There is only one Earth, and our job as humans is to maintain and support the growth and lives of all species. By working together, we may one day see sea otters, as well as all other species, safely live in unity.
Bodkin, James L. Long Term Effects of the Exxon Valdez Oil Spill. 2012. Print. Chanin, Paul. The Natural History of Otters. Helm, 1988. Print. Love, John A. Sea Otters. Fulcrum Pub., 1992. Print. “Otter Spotting Locations.” Friends of the Sea Otter, Friends of the Sea Otter, 19 Nov. 2014. |
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