The blue whale is the largest animal on Earth, with adults reaching lengths of over 90 feet and weighing up to 200 tons.   ︎   Cows have best friends and can become stressed or anxious when they are separated.   ︎   The mantis shrimp has one of the most powerful punches in the animal kingdom. Its claw can accelerate faster than a bullet, striking with the force of a .22 caliber bullet.   ︎   Some birds, such as pigeons and homing pigeons, have the ability to navigate using the Earth's magnetic field as a compass.   ︎   The Arctic tern holds the record for the longest migration of any bird, traveling about 44,000 miles round trip each year from the Arctic to the Antarctic and back.   ︎   The mimic octopus has the incredible ability to change its shape, color, and behavior to imitate other marine creatures, such as sea snakes, lionfish, and flatfish.   ︎   Female ferrets can die if they do not mate while in heat. The hormonal surge during heat can lead to a life-threatening condition called aplastic anemia.   ︎   The cheetah is the fastest land animal, capable of running at speeds up to 70 miles per hour (113 kilometers per hour) in short bursts.   ︎   Elephants are known for their intelligence and have the largest brains of any land animal. They are also capable of displaying emotions like joy, grief, and empathy.   ︎   The axolotl, a type of salamander, is capable of regenerating entire limbs, including the spinal cord, heart, and other organs.   ︎