Physical Statistics

Compared to Terran males, the average Homo-Reptilicus Sirius male is slightly taller and heavier. Conversely, the average Sirian female is shorter and smaller than her Terran counterpart.

	Average Height	Average Weight	Average Lifespan
Sirian Male	178 cm	86 kg	76 Sirian years
Sirian Female	160 cm	63 kg	68 Sirian years

Note for females: Gestation period is 2.5 months; all Sirian young are carried in an oviparous state and birthed in a soft-shell egg after which hatching occurs immediately.

Physiology

The reptilian Sirians are similar in chemical makeup and physiological nature to Terrestrial reptiles. However, Sirians are the dominant lifeform on their planet, comprising over 80% of total lifeforms on Sirius IV.

Like Terran Homo sapiens, Sirians walk upright and erect. The Sirian skeletal structure is similar to that of a human, although slightly lower in calcium. The bones of the spinal vertebrae are smaller and terminate in a short tail, a vestigial remnant of the past. The skull is ossified and bony, as in Terrestrial reptiles, and is fixed except for a distendable jawbone to facilitate consumption of large prey. The bony plates that protrude above the eyes and across the head are vestigial; once used in defense they now help in the body’s cooling.

Sirian internal organs are closely similar to those of a Terrestrial crocodile. The heart is divided into five chambers and beats 52 times per minute. The circulatory system is intricate, branching out into fibrous bunches toward the extremities. Due to the complexity of this circulatory system, Sirians are warm-blooded and need no outside temperature augmentation to remain comfortable. Sirian blood is copper-based, hence its green color, and rich in antibodies and sparse in corpuscles. Those Sirians in the Terran fleet have been extensively vaccinated against most Terran bacteria.

The digestive and ingestive system of Sirians is similar to that of Terrestrial snakes, including a highly developed stomach. Sirians prefer live prey or freshly-killed meat. Sometimes by choice but often due to lack of meat, Sirians consume raw, mineral-rich vegetables as a dietary supplement. Fried or prepared foods cause gastric upset. The excretory system makes provision for solid and liquid waste through a single large kidney organ.

Sirian lungs are both functional and operate best in low-altitude topography and damp climates. Sirian skin is covered by dermal plates, or scales, and is extremely osmotic. To keep their dermal from drying and cracking, Sirians bathe regularly in oil-rich water. For Sirians in the Terran fleet, a silicon-based lubricant coats the inner layer of their artificial "human skin." This skin is devoid of feeling, but is thin enough to allow some sensory transmittal and gas permeability.

The optical arrangement of Sirians is purely reptilian, with a single vertical slit instead of a round pupil. The Sirian eye possesses sufficient cones to allow pale color vision, and it is extremely sensitive to light due to the density of rod neurons. Olfactory senses are less highly developed than that of Terrans, but are more functional in filtering out airborne particles. The Sirian auditory system is composed of a vibrating tympanic membrane directed inward by a simple ear arrangement.

Sirians have a built-in defense mechanism in the form of an acidic neurotoxin similar to Terrestrial rattlesnake venom. The toxin is located in a maxillary gland (like the human parotid gland) and can be sprayed by a Sirian voluntarily. The atomized venom is airborne and irritating to humans, causing dizziness, heart fibrillation, and shortness of breath.

Pollution and warfare on Sirius IV have left the planet’s atmosphere laden with heavy gases, such as CO₂, Argon, and Krypton. The residual build-up of these gases in Sirian’s vocal cords gave them the quavering, reverberating pitch to their voices. However, this condition is only temporary, and for Sirians in the Terran fleet it diminished after prolonged exposure to Earth’s oxygen-rich atmosphere relaxed their vocal cords.

"Red Dust" Bacterial Weapon

As a previously-unknown bacteria and therefore one not initially vaccinated against, E. coli mutagena dealt a major blow to the Terran forces, resulting in a temporary retreat. Attempts to create a stable and mass-reproduceable inoculation have been unsuccessful to date.

The bacterial weapon was first discovered by known Resistance leader Doctor Juliet Parish a year after the initial Terran Invasion. The organism was a variant of E. coli found in the digestive tracts of Robin Maxwell’s hybrid children, unfortunately fatal to the more reptilian twin. The Resistance manufactured the bacteria in mass quantities, encapsulated like yeast, for distribution. Rehydration would reactivate the organism for inoculation of food and water chains. As a result, the Earth was (temporarily) fortified against Sirians.

The red dust is fatal to Sirians, not by infection, but rather by allergic reaction. Flagella of the bacteria possess "O-antigens" which trigger an immediate allergic reaction upon contact with skin, eyes, or the respiratory tract of Sirians. Possibly, the massive vaccinations to Terran fleet personnel have hypersensitized them to allergens. Symptoms of the common human cold and respiratory ailments were reportedly problematic among many fleet personnel.

Further research at Science Frontiers revealed that the exotoxins of the red dust, in high concentrations, are also toxic to humans. The red dust caused a deadly side-effect in terrestrial agriculture, producing blight in food crops such as corn and wheat. Other side effects include mutations and stillbirths among animals, and marked increase in respiratory ailments among humans living in areas with high concentrations of red dust deployment.

In addition, periodic seasons of cold temperatures are necessary for the mutant strain of the bacteria to regenerate and remain effective. Consequently, the warmer regions of Earth have lost the protection of the red dust. Because the side effects prevent the humans from constantly redeploying the bacteria, the path for re-invasion has been opened.