Manatee
Manatees, also known as sea cows, inhabit coastal waters and rivers. They are slow, bulky creatures that must periodically rise to the surface to take in air. According to the "National Geographic" website, manatees typically measure 8 to 13 feet in length and weigh between 440 to 1,300 lbs.
American Alligator
The length of the adult male American alligator usually falls between 13 to 14.7 feet, according to the University of Michigan BioKids website. Female American alligators are smaller but still measure 9.8 feet on average. Lengths of 16 to 20 feet have been reported in the past, but confirmed sightings of such vast alligators are rare.
Sharks
Despite generally being regarded as large animals, only 10 of the 465 species of sharks regularly reach a length of over 13 feet, says the ReefQuest Centre for Shark Research website. Species that do reach a maximum length of about 13 feet include the shortfin mako shark, the blue shark and the oceanic whitetip shark.
Snakes
A number of snake species grow to about 13 feet in length. According to the "National Geographic" website, king cobras can reach 18 feet in length, but 13 feet is more common. Boa constrictors and Burmese pythons also can grow up to 13 feet long, but rarely exceed it in the wild.
Rhinoceros
The adult white rhinoceros grows to a length of between 12 to 15 feet. After the elephant, the white rhino is the world's second-largest land animal. The slightly smaller black rhinoceros typically measures 10 to 13 feet in length.
Hippopotamus
The hippopotamus is the third-largest land mammal in the world, after elephants and white rhinos, according to the African Wildlife Foundation website. Adult hippos can weigh in excess of 3 tons and typically grow to lengths of about 13 feet.
Giant Gippsland Earthworm
The world's longest earthworm lives in the soils of Australia. According to the Australian Fauna website, the giant Gippsland earthworm normally has a length of about 6.5 to 10 feet, but the longest on record measured an incredible 13 feet. Due to a decline in its population, the Gippsland earthworm has become a protected species.