Soraks: Martian Cats
For more details, see the entry in Martian Wildlife for "Cats From Mars".
Synthetic Protoplasmic Men:
Hormads are are grotesque synthetic organisms originally created by Martian scientists to serve as slaves, workers, warriors, etc. Hormads are grown in giant vats from protoplasmic masses (see Proto-Shoggoths) and hypnotized into generally humanoid forms, though the process is far from perfect, often generating in monstrosities that diverge in shockingly vast degree from any ideal human form.
Hormads originally appeared in Edgar Rice Burroughs' "Barsoom" novels.
Plant Men from the polar crater valley Dor are strange creatures between 10 and 12 feet in height, similar in form to humans, with a head and face that are featureless except for a single white eye and a "nose like an open wound", tantacled arms that end in sucking mouths full of grasping talons and needle-sharp teeth used to feed on tender vegetation or blood sucked from living animal and humanoid victims, a body covered in shaggy black tendrils or "hair" resembling earth-worms, and a tail that tapers from a round profile to a flat blade shape at the tip. These strange creatures are herded and controlled by cannibal Therns as a trap for those unfortunate travelers the Therns trick into journeying into the Martian valley Dor: after the Plant Men have drained victims of their blood, the corpses are gathered and butchered as meat for the tables of the Therns.
Plant Men originally appeared in Edgar Rice Burroughs' "Barsoom" novels.
Savage, hairy, albino giants with four arms found in subterranean areas of the Dreamland of Barsoom. These beasts are sometimes described as resembling a "large white gorilla with extra arms", but in fact actually seem to be savage and feral Gugs.
Leech of Yoh-Vombis
A strange, nocturnal or subterranean, slug-like parasitic creature which clings turban-like to the top of a humanoid victim's head, dissolves the flesh, skull, and parts of the brain for food, and then controls its host, driving the remnants of its victim down into the darkness of hidden vaults beneath the ruins of Martian cities, to a near-immortal fate worse than death. See Leech of Yoh-Vombis for more details.
The Yashta pestilence is a kind of green mould that eats all the bones of the body, starting with the teeth and nails; believed to have been responsible for the virtual extermination of the Yorhis, one of the intelligent species of Ancient Mars. A black, mossy variety or life-stage of Yashta forms into a strange, crawling, mat-like, carnivorous monstrosity, capable of creeping slowly across the Martian surface in search of a host; this form has sometimes been mistakenly called a "vortlup" (see below).
Red Weed (Red Creeper)
The Uliri invasion may also brought with them, perhaps accidentally, the "Red Weed" or "Red Creeper", a dense red vine that glows purple at night, tastes vaguely metallic, grows and reproduces explosively in water, and shares the Uliri vulnerability to Earth's bacteria. The Red Creeper seems to have flourished on Mars, where it has flooded the Martian canals, choking whole regions of that dying world off from a much-needed water supply; it is likely that the Red Weed, like the Uliri, are an invasive species alien even to Mars, with the Red Creeper either serving as food for the Uliri invaders, or trailing along with them as microscopic spoors and spreading unnoticed or poorly understood by the Uliri due to their alien disregard for sanitation, disease, and decomposition.
Red Weed is the creation of H.G. Wells, from his story War of the Worlds.
Their food-supplies and water-barrels were carried on the backs of three of those curious mammals called vortlups, which, with their elongated legs and necks, and horny-plated bodies, might seemingly have been some fabulous combination of llama and saurian. These animals, though extravagantly ugly, were tame and obedient, and were well-adapted to desert travel, being able to go without water for months at a time [and] wholly insensible to the blowing sand in their scaly mail...."
- Clark Ashton Smith, "The Dweller in the Gulf"
The Vortlup is a creation of Clark Ashton Smith, and appears in his Martian stories as a pack animal native to Mars, and roughly equivalent to a llama, camel, or dromedary. (In an early draft of "The Vaults of Yoh-Vombis (fiction)", the Vortlup apparently appears as a mat of carnivorous black moss.)
Zitidars, a large six-legged draft animal similar to a mastodon, are still bred on Mars by the Uliri and their Red Martian slaves as a food source for the Uliri invaders, fattened on the Red Creepers and stagnant water of Martian canals.
Zitidars originally appeared in Edgar Rice Burroughs' "Barsoom" novels.
A few feral Thoats, six-legged native Martian riding animals, can still be found in the wild dead seabeds of Mars, with a handful serving as the riding animals of Green Martian Raiders, but most domesticated examples seen today can be found in the Martian Dreamland of Barsoom.
Thoats originally appeared in Edgar Rice Burroughs' "Barsoom" novels.
Calots are intelligent - and perhaps sentient - ten-legged dog-like creatures with wide frog-like mouths, which once served as the Martian equivalent of dogs; they are said to have been among the fastest creatures on ancient Mars.
Today, Calots are almost never seen outside of the Martian Dreamland of Barsoom, and like many other Martian life forms are believed to be extinct on waking Mars, though a few examples may still live wild in dark corners of Mars working together in feral hunting packs on dead Martian sea bottoms and serving as hunting hounds in the company of Green Martian Raiders, if reports by Martian cryptozoologists and other eccentrics are to be believed.
Unlike Martian cats (Soraks), which have intelligence comparable to humans, Calots are not known for any ability to speak languages, use tools, or develop complex social behavior; Calot intelligence may only be slightly higher than that of dolphins and whales or great apes. Nevertheless, in the Dreamlands these Martian "dogs" display a remarkable level of intelligence and loyalty for an animal, going to great lengths to protect and help those who treat them with kindness, often showing particularly great affection for human Dreamers.
Calots originally appeared in Edgar Rice Burroughs' "Barsoom" novels.
Other Life on Mars
"Although scientific evidence seems to indicate that Mars is a cold, desolate world, many scientists today speculate on what the planet might be like if conditions were somewhat different. With a little more water and oxygen than expected, there could be an astonishing array of life on Mars, a totally different sequence of living things following its own pattern of evolution.
"There might be plant life that migrates in search of richer soil; there might be plants that feed on other plants, or even plants that feed on themselves.
"And if animal life has developed on Mars, it too may have taken many new and unexpected forms.
"There might be animals with heavy insulation to conserve body heat in the sub-freezing night. Or perhaps the bitter surface conditions have driven some life underground to develop in a dark, mysterious environment.
"If it is true that there are dust storms on Mars, life could have developed ways of protecting itself. On the other hand, there might be creatures that actually thrive on the ever-present dust: some organisms working with powerful digestive acids may be able to feed directly on minerals in the rocks, leaving a fantastic Martian sculpture in their wake.
"If in the thin Martian air there are creatures that can fly, their wings must of necessity be four times as large. However, flight might be achieved by other means. On Mars, even as on Earth, live would surely be a competitive struggle for survival. There might be fantastic hunters who kill by concentrating the heat of the Sun on their victims, devastating creatures that envelope their quarry in shrouds of poisonous gas, or maybe ominous ultra-sonic beams who shatter their prey with high-frequency sound waves.
"It is possible that entirely new chemical patterns of life may have developed on Mars: life based on the silicon atom instead of carbon would be more resistant to the extreme cold, providing a whole new range of weird forms. Feeding on the drifting sand, tall crystal spires may grow to maturity in a single day, only to be shattered in a crescendo of destruction in the cold Martian night. Just as it is impossible to conceive an intelligent life totally different from our own, so we may find our Earth-trained minds unable to comprehend the weird phenomena that could exist on this strange new planet!"
- Disney's Tomorrowland: Life on Mars