The age of a manatee can be determined by their teeth.
FICTION! Manatees’ marching molars are always being ground down by the soil and plants they eat and are replaced by more growing in from the back. Other than outside features, the only way to determine the age of a manatee is by the bones in their inner ears, which grow similar to tree rings!
Manatees' tails (flukes) are specially adapted to maintain their body temperature.
FACT: The arteries in the base of the manatee's fluke, or peduncle, are branched like a broom, have very thin walls and lie next to similarly shaped veins. As arterial warm blood flows away from the heart, heat is transferred to the blood in the veins returning back to the heart. This counter-current heat exchange is an "optimal heat-trap design" and is also found in whales, dolphin and birds' feet. In the same area, manatees have a deeper set of veins which allows arteries to expand and results in dissipating heat, ie, cooling
Manatees' facial hair, vibrissae, are the only sensory hairs on their body.
FICTION: Manatees have approximately 3000 tactile hairs on their body and each are stimulated by 20 to 50 nerve cells called axons. This unique sensory system can detect approaching creatures, stationary objects, water currents and low frequency vibrations, it does not exist in any other creature on land nor in Water.