Vaikan internal physiology is suited to their cold, low oxygen homeworld.
Vaikan, although are analogous to hominids, are actually liquivores. As Vaikan live in a very arid climate, water is difficult to find. The inside of their mouth is lined with rows of long teeth designed to drain fluids, and they have a forked tongue to detect if their prey is edible. While several other species on Ucharpli evolved proboscises, the Vaikan required an alternate solution to extracting nutrients from tough, scaly prey who could resist the penetration of a proboscis. The solution was to develop an analogous mouth filled with sets of teeth to crush the prey into easier to extract pieces. Saliva glands in their mouth make a single Vaikan bite highly toxic. The chewing process is largely accompanied by highly acidic saliva which breaks down the object into its raw nutrients. Because of how acidic the saliva is, the teeth rapidly grow back - Vaikan often gnaw on a piece of wood or other hard substance between meals.
The nutrients they ingest first go through their livers which is wound around the upper spinal cord in the neck area. This serves as their only checkpoint where food is detoxified before getting sent along tube-like structures which deliver them to the life essential organs, primarily the hearts and the brain. If the liver detects something dangerous such as hydrogen peroxide, their only means through removing the toxic agents is through sneezing. Naturally, with the lack of any other organs to break down food, their livers are extremely powerful offering them remarkable resistance to substances such as alcohol.
A Vaikan's sense of taste is not per se the same as humans. Instead, what they enjoy most is the richness and texture of the nutrients upon its passing into the system. The richer in nutrients the substance it is, the greater feeling of euphoria that gets triggered. Vaikan cuisine mostly consists of potato analogues or large herbivores. Most Vaikan meals of today consist of highly nutritious liquid mixtures.
In times of famine, they can use their chloroplast layer, hidden under their skin, to gather emergency nutrients. It is believed to have appeared due to a symbiotic evolution. While not essentially to their survival, this allows them to gather an emergency source of energy. Effectively, a Vaikan can simply warm up by standing out in the sun for a few minutes. Even when the sun is not out, their scales still retain heat which allows them to survive in subzero climates. This has allowed them to thrive even in ice deserts.
Common to terrestrial egg-laying animals, Vaikan excrete uric acid. This assists in eliminating toxins and conserving water.
For breathing, Vaikan have triangular shaped noses which contain an olfactory bulb. They also have a trachea, that connects their mouth to their lungs. As a result, their mouth doubles as both a method of breaking down food as well as breathing.
To adapt to the lower oxygen levels, Vaikan actually have two hearts to be able to cycle oxygen throughout the body very quickly, and they also have large lungs. The openings in their arteries are considerably wide, and on instinct, they can move around to redirect blood flow.
Vaikan also have large vocal cords. Their mouths can form many different shapes to form distinct sounds, and their voice as a flanging effect, with the second voice sounding like a series of croaks and vibrations. This croaking effect is actually a vestigial structure that stems from a time before Vaikan had begun to speak. A non-croaking effect is recessive to croaking, and it can be controlled through genetic altering.
The Vaikan skeleton has a high concentration of metals, much like the bones of other Ucharpli-native animals. When a Vaikan draws nutrients from an animal, they also draw microscopic particles of metal into their system which get sent throughout their body. Their bones, interconnected and wiry, serve as conduits from which the Saskana's area of the brain can send signals and regulate life functions.
A Vaikan brain is divided into three general regional sectors which are responsible for processing different sets of information. The three areas are roughly equal in size.
Rather than chemical signals, Vaikan rely on electrical signals generated by Saskana's area to carry out life functions. These signals stimulate the growth of muscles and act as transistors when carrying out processes.
The right sector, Krayhan's area, is responsible for processing logic, language and reasoning.
The left sector, known as Morduin's area, is responsible for expressing emotions, recognizing faces and creativity.
The back sector, Saskana's area is responsible for the management of life functions, and is the conduit for generating bioelectricity.
When a Vaikan is in a frenzy, both Morduin's area and Krayhan's area go dormant, allocating power mainly to Saskana's area. This explains why Vaikan are "not themselves" when under such effects.
Among the Vaikan's hardened skin and metallic skeleton, the back of the head is considered a weakpoint due to the sensitivity of the area. A significant blunt force to the area will render a Vaikan unconscious.
Adrenaline is toxic to Vaikan because it interferes with the brain's ability to manage life functions. In small amounts, the adrenaline creates false signals causing unusual sensations and hallucinations.
In larger amounts, the body begins to sense imminent danger. To protect itself, the two front sectors go dormant to allocate more power to Saskana's area to expel the adrenaline from the system, causing the Vaikan to enter a frenzy. Dangerous in vast amounts, adrenaline is considered an illegal narcotic exclusive to their species.