Spectacled Chirorbite

Chirorbites are likely the most derived members of the superphylum Pseudarticulata. It was first believed that pseudarticulates, despite their unusual morphology, are members of the Martian animal kingdom, as they are heterotrophic and mobile, at least at some point in their lives. This assumption turns out to have been wrong.

Having already met animals that behave like plants, it should maybe not come as a surprise that on Mars there are also “plants” that behave like animals. It now seems clear that pseudarticulates are unrelated to Arezoa, but instead are deeply nestled within the Fractaria, a kingdom which otherwise only includes immobile organisms with no nervous system that live autotrophically or through passive filter-feeding. The commonalities are not only evidenced by their characteristic glide-symmetry but now also molecular data.

Pseudarticulata likely descend from an aquatic ancestor not too different from the frondomorph monvexillans in the foreground. These organisms originally were sessile autotrophs, filter-feeders or osmotrophs their whole life, their chiral body-isomers being constructed of ciliated filtering-chambers and held up by a hydroskeleton. While it is effective for such a lifestyle, such a bodyform is restrictive when wanting to develop more complex morphologies and behaviours. The majority of Fractaria have worked around this by opting for a clonal, colonial lifestyle, such as the two organisms seen here at the back. This represents a path of increasing complexity through external compartmentalization. Pseudarticulata on the other hand went down the other path, the one of internal compartmentalization. Their ancestor must have been a single frondose-organism, which, instead of being anchored straight on the ground, lied flat on the sea floor with its leaf-surface and was capable of crawling across it using cilia, likely using the filtering chambers at the bottom surface to feed on algal mats, while those at the top became specialized in respiration. The former holdfast, now being the first thing that comes into contact with the world as the body crawls forward, soon began being studded with sensory cells, the beginnings of encephalization.

Organisms such as the Spectacled Chirorbite represent a major improvement on these primitive beginnings. Out of sensory and contracting cells, already present in the earliest fractarians, has now evolved a nervous system, with muscle-tissues to control, evolved completely independently from the Arezoa. The small channels which used to connect the chambers of each isomer have become a true, zigzagged through-gut. The formerly gelatinous body is now covered in a tunicine exoskeleton. The chambers at the bottom sole of the body have given up their digestive function. Instead, they now house hydraulic tubefeet, evolved out of extensions of the hydroskeleton’s mesenteries. Instead of cilia, the Chirorbite now uses these to walk and can also fully retract the tubefeet into their pores, much like a starfish. The primitive cephalon has become a proper head segment, housing little tasting, smelling, and hearing feelers and, most conspicuously, eyes. Underneath lies a crescent-shaped mouth with two hardened lip-plates. The chirorbites use this shearing-structure to feed on low-growing vegetation, including their botanical cousins, as well as very small trichordates, spirifers and onychognaths. Its most common prey is the Menamin, which is also a pseudarticulate, but worm-like with no exoskeleton and limbs.

In perhaps a twist of irony, chirorbites are among the few Martian organisms, along with aspiderms, to have evolved liquid-filled lens-eyes, not unlike yours or mine. These eyes, usually five of them, are covered underneath a translucent tunicine window of the exoskeleton. For unknown reasons, the chirorbite also seems to have eyelid-like membranes underneath this hood to close its eyes. It is funny how an organ this basic can generate much sympathy as Man interacts with his fellow alien. Looking at the Chirorbite’s face, one may feel like catching a glimmer of consciousness, perhaps even a soul, behind those eyes, which one does not perceive when looking at the inanimate compound-eye of an arthropod. Yet, the “brain” of the Chirorbite is a ganglion the thickness of a lentil and it is confronted with minds that are as distant to its consciousness as its is against the vegetative relatives it feeds on. An intellect, which is as vast as it is cool and unsympathetic, now rears its malevolent jaw apparatus into the picture, leaning on avipodous legs over a chirorbite, helpess after it had been turned onto its back. The polychaete-like grin of the rannu is made all the more sinister by its maw having no eyes to speak of, just four black holes representing the nostrils and earholes. Man is unfortunately more likely to find his equal among the stars in such minatory beings.