Skymanatee

Skymanatees are large, fully airborn, mostly herbivorous mammals sometimes known as sky cows. They measure up to 4.0 metres (13.1 ft) long, weigh as much as 590 kilograms (1,300 lb), and have paddle-like flippers. Skymanatees are occasionally called sky cows, as they are slow plant-eaters, peaceful and similar to cows on the ground. They often graze on plants (including grass, flowers, vegetables, and even fruits and leaves) all over the world's landscape.

Description
Skymanatees have a mass of 400 to 550 kilograms (880 to 1,210 lb), and mean length of 2.8 to 3.0 metres (9.2 to 9.8 ft), with maxima of 4.6 metres (15 ft) and 1,775 kilograms (3,913 lb) seen (the females tend to be larger and heavier). When born, baby skymanatees have an average mass of 30 kilograms (66 lb). They have a large, flexible, prehensile upper lip. They use the lip to gather food and eat, as well as using it for social interactions and communications. Skymanatees have shorter snouts than their fellow marine sirenian relatives, the dugongs. Their small, widely spaced eyes have eyelids that close in a circular manner. The adults have no incisor or canine teeth, just a set of cheek teeth, which are not clearly differentiated into molars and premolars. These teeth are continuously replaced throughout life, with new teeth growing at the rear as older teeth fall out from farther forward in the mouth. This process is known as polyphyodonty and amongst the other mammals, only occurs in the kangaroo, fully aquatic manatees, and elephant. At any given time, a skymanatee typically has no more than six teeth in each jaw of its mouth. Its tail is paddle-shaped, and is the clearest visible difference between manatees. Females have two teats, one under each flipper, a characteristic that was used to make early links between the manatee, the skymanatee, and elephants.

Skymanatees, along with aquatic manatees, are unusual amongst mammals in possessing just six cervical vertebrae, which may be due to mutations in the homeotic genes. All other mammals have seven cervical vertebrae, other than the two-toed and three-toed sloths. Like horses, they have a simple stomach, but a large cecum, in which they can digest tough plant matter. In general, their intestines have a typical length of about 45 meters, which is unusually long for animals of their size. Skymanatees and manatees are the only animal known to have a vascularized cornea.

Behavior
Apart from mothers with their young, or males following a receptive female, skymanatees are generally solitary animals. Skymanatees spend approximately 50% of the day sleeping in the earth's atmosphere without any harm, descending for oxygen regularly at intervals of less than 20 minutes. The remainder of the time is mostly spent grazing in grasslands, savannahs, farmlands, parks, fields, and other grassy areas on land. They have been known to live up to 90 years.

Locomotion
They "swim" in a similar style to aquatic manatees. generally, skymanatees swim at about 5 to 8 kilometres per hour (3 to 5 mph). However, they have been known to swim at up to 30 kilometres per hour (20 mph) in short bursts. Skymanatees, along with skycetaceans, are among the first and, possibly, only known animals without wings to fly, due to their helium-filled organs to allow them to "swim" in air.

Intelligence and learning
Skymanatees are capable of understanding discrimination tasks and show signs of complex associative learning. They also have good long-term memory. They demonstrate discrimination and task-learning abilities similar to aquatic manatees, skydolphins, aquatic dolphins, and pinnipeds in acoustic and visual studies.

Reproduction
Skymanatees typically breed once every one year; generally a single calf or two (or even three) are born. Gestation lasts about 8 months and to wean the calf takes a further 11 to 15 months.

Communication
Skyanatees emit a wide range of sounds used in communication, especially between cows and their calves. Adults communicate to maintain contact and during sexual and play behaviors. Taste and smell, in addition to sight, sound, and touch, may also be forms of communication.

Diet
Skymanatees are herbivores and eat over 960 different plant (including grass, leaves, flowers, fruits, vegetables, vines, and even thorns). Using their divided upper lip, an adult skymanatee will commonly eat up to 10%-15% of their body weight (about 50 kg) per day. Consuming such an amount requires the skymanatee to graze for up to seven hours a day. Skymanatees have been known to eat small amounts of birds from giant man-made nets used by humans to catch birds.

Feeding behavior
Skymanatees use their flippers to "walk" along the land whilst they dig for plants and roots in the ground. When plants are detected, the flippers are used to scoop the vegetation toward the skymanatee's lips. The skymanatee has prehensile lips; the upper lip pad is split into left and right sides which can move independently. The lips use seven muscles to manipulate and tear at plants. Skymanatees use their lips and front flippers to move the plants into the mouth. The skymanatee does not have front teeth, however, behind the lips, on the roof of the mouth, there are dense, ridged pads. These horny ridges, and the skymanatee's lower jaw, tear through ingested plant material.

Dentition
Skymanatees have four rows of teeth. There are 6 to 8 high-crowned, open-rooted molars located along each side of the upper and lower jaw giving a total of 24 to 32 flat, rough-textured teeth. Eating gritty vegetation abrades the teeth, particularly the enamel crown, however, research indicates that the enamel structure in manatee molars is weak. To compensate for this, manatee teeth are continually replaced. When anterior molars wear down, they are shed. Posterior molars erupt at the back of the row and slowly move forward to replace these like enamel crowns on a conveyor belt. This process continues throughout the skymanatee's lifetime. The rate at which the teeth migrate forward depends on how quickly the anterior teeth abrade. Some studies indicate that the rate is about 1 cm/month although other studies indicate 0.1 cm/month. This process of teeth being continually replaced is known as polyphyodonty and amongst other mammals, only occurs in elephants, aquatic manatees, and kangaroos.