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Sea Otters: Plundered Populations
Transcript of Sea Otters: Plundered Populations
(natality) Death Rate
(mortality) Immigration Emigration The number of live births in a population over time The number of deaths in a population over time When individuals of a population enter a different population When individuals of a population leave the area Sea Otters: Sea Otter History Plundered Populations Before 1750, an estimated 16,000 sea otters lived in California.
Today, there are less than 3,000 sea otters living in California.
Why? Alaskan Sea Otter Russian Sea Otter Southern Sea Otter The Role of Sea Otters in the Kelp Forest Sea otters have over one million hairs per square inch of otter fur. Compare that to humans who only have one hundred thousand hairs on their entire head! Sea otters have to consume approximately 25% of their body weight in food each day. That’s like a 150-pound person eating over 150 hamburgers a day! Otters are able to dive down as deep as 330 feet (100 meters) and stay underwater for up to 7 minutes. An otter is a "keystone species." Keystone species are species that have a greater impact on their environment than what the population numbers predict. In other words: for how few they are, they are incredibly important for that environment. Without them everything would fall apart. Kelp forests provide a habitat as well as a food source for a variety of animals. Sea otters need a lot of energy to stay warm in the cold water, so they eat large quantities of their favorite food: sea urchins. Sea urchins, being herbivores, feed on kelp. When the sea otters were nearly eliminated by hunting, sea urchin populations increased greatly, and kelp forests nearly disappeared. Why? Because the kelp was eaten down to the bare rock by hordes of sea urchins! When the sea otters were declared an endangered species, and therefore protected from hunting, the otter population recovered and the kelp forests grew back.