Manatees are large, gentle, slow moving mammals. they are entirely aquatic, meaning they spend their full lives in the water. manatees are found in the warm ocean waters off the southeastern united states, caribbean islands, eastern mexico and central america. they cannot survive for long periods of time in waters below 68° fahrenheit.
manatees evolved from four-footed land mammals over 60 million years ago. manatees are distantly related to elephants. they range in color from gray to brown, and the average adult is about 10 feet long and weighs between 1,500 and 2,200 pounds. life expectancy is about 60 years. newborns range in size from 4 to 4.5 feet, and weigh about 60 pounds. manatee young are called calves. calves are dependent on their mother for up to 2 years.
manatees live in shallow water habitats. they thrive well in fresh, salt and brackish waters. brackish water is the mix of fresh and saltwater that occurs where freshwater bodies flow into the ocean. in florida, they travel considerable distances during the winter to access warm water. manatees are herbivores, that is to say, they eat only plants and vegetation.
in the u. s. the manatee is listed as a federally endangered species. it is estimated that there are less than 3,000 remaining manatees in florida today. major threats to manatee survival are human activities such as boat-related injuries and deaths, habitat loss or damage, and in some countries, hunting.
question:
the passage mentions that manatees are endangered, mainly due to human activities. what other detail from the passage might explain why manatees are so easily threatened by people?