Mutant Turtle Species in TMNT: Mystic Forest | World Anvil

Mutant Turtle

Mutant Turtles are the type of Mutant that brothers Leonardo, Raphael, Donatello, and Michelangelo are. Though each of the boys are different species of turtle, they have a lot of things in common about their mutations.

Basic Information


Physically the brothers all have certain physical characteristics in common. They are all bipedal, humanoid turtles with shells on their backs. They're fronts have a sturdy, cartilage plastron which wrap around their front torsos. They have human spines and rib cages and a small fatty layer of tissue between their shell and spine allows for flexibility. Their joints can naturally pop out of place and collapse to allow them to hide inside their shell.   They only have three fingers on each hand and two toes on their feet. Their feet have elongated heels for balancing. A few of them, like Leo and Donnie, maintain the webbing on between their fingers and toes from their previous aquatic life styles.   They each have a stubby tail that pokes out from the base of their shells. This tail moves freely and will often wiggle based on the turtle's mood.  

Facial characteristics

Their skulls are human-like, able to hold a normal, human sized brain. Their jaws form the shape of snouts, ending in beak-like lips. They have human teeth, though they are sharper than normal, and Raphael has a few fangs in his mouth. They lack noses, and breathe through small nostrils at the end of their snout. They have internal ears that are covered with a thin later of skin located around where they would be on a human.  

Perception and Sensory Capabilities

The turtle's senses are on par with humans for the most part. Their hearing is slightly weaker, while their sense of smell is stronger.

Genetics and Reproduction

There aren't enough mature, adult mutant turtles of both sexes to get accurate data on this subject, but theoretically; they'd be able to reproduce with humans or other humanoid mutant species equally. It appears that females would still possess a cloaca and would lay eggs, likely ones large enough to produce human-sized offspring.

Growth Rate & Stages

The turtles started out much smaller than human babies when they first mutated, and grew rapidly in the first 2 years of their life. When they first mutated, they averaged 8-9 inches tall, with Mikey --the smallest-- only being 7.5 inches. By age 4 Leo and Raph had developed to the average height for a toddler their age.   From that point on, the turtles developed at a similar rate to humans, even experiencing their own form of puberty around the age of 13, which mostly consisted of things like their voices dropping and hormonal changes. Currently the only known specimens of this mutant variant are adolescents, who still have some growing to do.

Dietary Needs and Habits

The turtles can eat most human food without issue, but when they were young they required a diet closer to their turtle counterparts, being made up mostly of fruit, leafy greens, raw fish and worms. They will still get craving for this even as adults, and will sometimes eat things like bugs and turtle pellets as snacks.

Biological Cycle

The turtles metabolism combines that of a warm-blooded human and a cold-blooded reptile, making them mesothermic. They can produce a small amount of their own body heat and are capable of temperature controlling behaviors like sweating and shivering, but it is weaker than most mammals or birds, and easily influenced by their external environment.   Their average body temperature rests at 89.5 °F, but can drop far below that if the external temperature drops low enough. This causes them to become sluggish and sleepy in cold environments, and they will often enter a brumation period during the coldest months of the winter. It's a necessary step in their yearly cycle and missing it can cause them to feel sick during the winter.   Another thing that occurs annually is the shedding of the scutes, the small plates that make up their shells. Around springtime a new layer of scutes will grow and the old layer will begin to flake off. Often times they have to be removed manually, or else they will begin to dry out the skin and itch. The turtles will often assist each other in peeling off these scutes, which naturally pleases their human instinct to groom socially.


The turtles tend to have mostly human intelligence and behave in a human manner most of the time, but they do retain a few turtle instincts;   They will naturally hide inside of their shells when startles, not usually completely but they will sink their head into their shells occasionally. It's also a natural defense mechanism when in danger.   Their shells being as sensitive as they are means that they react positively to being stroked. Running water also feels nice on their shells, and when they are particularly pleased, they will wiggle their bums.   They love sunlight warm spaces and will frequently take time to laydown and sunbathe on a nice day.   Though normal turtles do not frequently make noise, the turtles will growl, hiss, and chirp as an alternate form of communication. Before they could all speak this would be their primary means of communication, and too this day they will often chirp at each other as a comforting and reassuring gesture.

Art by Amevello Blue
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