Fybra

 
The deserts of Mars are treacherous, not just because of the sharp and craggy rocks and the constant risk of massive duststorms. Under some rocks can lie predators who do not like being awoken from their hibernation.

One of these is the fybra, a serpentine organism that can grow up to 60 cm long. It is a fyrm, a group of derived diplognath circulates. Like the hekubus, it is a soft-boded organism internally supported by a hydroskeleton, not unlike a rainworm. Its only hard-part is the skull and the two dorsal mandibles, made of calcite. Unlike the hekubus, fyrms have teeth and are covered head-to-tail in a dense pelt of setae-derived hairs. They evolved this insulation because they are actually endothermic organisms and therefore try to maintain a stable body-temperature.

Requiring more energy than cold-blooded animals of similar size, the fybra is relatively rare compared to onychognath predators such as the tynus or even the much larger cecrops. But its metabolism gives it one deciding advantage: It can hunt during the cold desert nights when others cannot.

Most of its prey consists of spirifers, pseudarticulates and small onychognaths. How exactly it tracks them is still a mystery. It probably does not see in infrared like some snakes can, as most of its prey is not warm-blooded. Its sense of smell is likely also not well-developed, having no nose beyond perhaps two breathing orifices at the base of the skull. Most likely then it tracks its prey through sound, using its large and solid lower jaw to pick up vibrations in the ground. Perhaps it is even sensitive enough to pick up the heartbeats of certain creatures while they sleep, as the fybra is often observed preying on them lying dormant in their burrows. As the fybra cannot dislocate its jaw like a snake, it uses its double mandibles to cut up its prey into nice bitesize pieces to swallow.

During the long dust storm months of winter, the fybra itself hides underground in burrows in order to hibernate. While it can dig by itself, it prefers to seek out burrows that have already been dug out by other creatures, such as shetaws, a kind of tortoise-like archaeocephalian.

How fybras reproduce has not been observed so far. Probably, like other fyrms, they lay eggs.