The Teenage Mutant Ninja Turtles were created by Kevin Eastman and Peter Laird and first appeared in Mirage Comics in 1984. Since then they've appeared in television shows, movies, video games and comic books. TMNT has been entertaining people for decades and every generation has looked different, but Leonardo, Donatello, Michelangelo and Raphael have always been there with their humanoid turtle anatomy, kicking butt.
If there were any doubts regarding the turtle's superhero nature, those have squashed thanks to recent team-ups with Batman and the Power Rangers along the way. The Turtles' super abilities aren't put on blast like many other popular heroes, but that doesn't mean they don't exist.
Anatomy and Powers
The TMNT were created by a mysterious radioactive ooze that mutated them into humanoid turtle creatures. The mutations culminated in heavily armored features like their shells and cranial plates. Their hands became tridactyl forelimb with opposable thumbs that allow them to maneuver their weapons and their feet are similar, but only have two digits. The Turtles's internal organs resemble human anatomy, including a chambered heart structure and similar intestinal system. They also possess the emotional depth of a human and many human interests and tastes -- like pizza, for one.
The Turtles have always possessed meta-human abilities like enhanced strength, speed, agility and reflexes. They're also resistant to cold. Splinter's ninjutsu training allowed the turtles to hone and strengthen their abilities to incredible levels. Leonardo even took his ninjutsu training to otherworldly heights by obtaining the ability to heal himself and others from fatal wounds. This healing ability goes beyond the Turtles' amphibious healing properties. The height of this power allowed Leo to cure himself of a so-called incurable venom when he was fighting Shredder's estranged daughter.
Super Turtle Shells
While their muscle and skeletal structures combine many elements from turtles and humans, the Teenage Mutant Ninja Turtles' shells are incredibly similar to real turtle shells. The plastron and the carapace combine to cover the Turtles' front and back to cover all their vital organs. Even the simpler animations show the shells divided into smaller subsections, which are points where the individual bones fuse and form into a shell.
Their shells take the place of their abdominal muscles and collar bones and relay a lot of synchronicity between their human and turtle anatomy. Their shells are bulletproof and can withstand enormous kinetic force, making them incredibly resistant in battle -- which allows them to more easily defend against multiple opponents at once. The shells also provide situational offensive capabilities, like when the turtles hurl themselves like cannonballs at their foes.
The Fifth Turtle
Jennika is the fifth member of the TMNT and is objectively the most unique turtle of the bunch. Not only was she human at one time, but she also worked for Shredder was one of Splinter and the Turtles' most deadly foes. After she was gravely wounded, the Turtles decided to save her life with a blood transfusion. Leo was Jennika's blood donor and his mutated blood transformed Jennika into a turtleoid, whereas the original turtles were turned into humanoids. Jennika's Turtle form is far more slender than her male counterparts and she dawns a bright yellow eye mask to complete her look.
Jennika's main weapon choice is a set of claws, keeping an element of her Foot Clan past with her during her new life as a hero in a half shell. It's Jennika's mental fortitude that sets her apart. Not only does she have an entire lifetime of human memories, she's dealing with all of the mental hurdles of a mid-life species change. Jennika brings a lot more weight and human nuance to her character, which makes her a completely new breed of Mutant Ninja Turtle.
Weirdest Changes
The turtles have gone through some changes over the years. While they generally remain the same, there have been some radical exceptions to the rule. One time, Leo lost his hand in a battle with a mutated Komodo Dragon named King Komode and in the same comics series, Raphael's face became permanently scarred. These incidents are no longer considered canon, but they provide an idea of the Turtles' healing limitations and the extent of their pain tolerance.
Donny and Raph have gone through the weirdest changes of them all, like the one time they turned into vampires during a collision with Universal Studio's classic monsters -- including Dracula. Donny also becomes a cyborg at one time when his body is damaged from a nearly fatal fall out of a helicopter. Donny merged with one of the cyborgs he and his brothers were fighting to save his life and the CPU altered his brain to make him more aggressive and feel less remorse. His extra mechanical features included blasters and improved armor.
The Teenage Mutant Ninja Turtles may have started as turtles mutated into humanoids by toxic ooze, but they have come a long way since and are now genuine heroes with incredible power.