Cuilco: Biology (another alien species)

Following on from my description of diophel, here’s another alien species living in the same setting. These ones are a tad more… well, alien.

Cuilco are a physically unusual species, in one very striking way: although they each possess one head, they appear to have two ‘bodies’ attached to it. That is, the cuilco body plan is that of an inverted ‘V’, with a head and neck emerging from the point of the ‘V’ – or, to put it another way, an inverted ‘Y’ with a very short stem.

Each ‘body’, or trunk, appears more or less the same at a glance. There is a ‘front’, or ‘belly’ to each, and a ‘back’. Each trunk narrows somewhat at the top, where the two trunks bend together, but this narrowing does not constitute a ‘neck’ in itself.

Each trunk has three pairs of limbs. The ‘upper’ or ‘first’ (pair of) pair(s) of limbs, nearest the head, is assymetrical on each trunk – the ‘outer’ limb is stronger and longer, while the ‘inner’ is shorter and weaker. These two inner upper limbs (one on each trunk) are the primary tool-manipulators, while the outer upper limbs are better suited for rough tasks. The second and third pairs of limbs on each trunk are symmetrical – the second (i.e. the middle) pair are vestigial and only used for sexual purposes, while the third (i.e. the lower) are very long, with several joints and prehensile feet. Each trunk also bears a prehensile tail – that on the left-hand trunk is shorter. [A small percentage of cuilco are ‘inverted’ – their left-hand trunk is like the right-hand trunk of most cuilco, and vice versa, but this usually occurs only alongside more serious developmental defects]

This peculiar double-trunk system is not the relic of some ‘doubling’ defect, but a reflection of their environment. The cuilco homeworld is warm and wet, volcanic and fertile, and is largely covered in immense forests – and has been since long before megafauna arose. In this environment, one succesful line of fauna were long, sinuous centipede-like creature with feeding parts located along the length of the body. As they grew larger, the number of feeding parts reduced to one, and the number of limbs reduced to only twelve. With one feeding head (and a move from the random food-finding of their smaller ancestors to purposeful hunting) there came a tendecy to put their feeding head in front, leading to the V-pattern body. The energy consumption this wastes is counterbalanced by their greater ability to move through the branches (thanks to their multiple limbs and the lenght of their reach), and by a degree of biological redundancy.

Each trunk is about three feet long, their neck and head adding another foot. Their rear (lower) limbs (legs) are perhaps three feet long again – their upper outer limbs (outer arms) are about two feet long, their upper inner arms around a foot, their short tail around two feet and their long tail around four or five (or six or seven in modern cuilco). Their head is relatively broad and flat, more like a salamander’s or a snake’s than a mammal’s.

Internally, the left-hand trunk contains the primary reproductive organs, the primary respiratory system, and the secondary digestive system. The right-hand trunk contains the primary digestive system, the secondary respiratory system, and the secondary reproductive system. Redundancy is built in to the cuilco body. Either trunk can be lost entirely, and the other still survive using their ‘back-up’ systems, although with greatly reduced vitality (cuilco with only a left-trunk will become weak and malnourished, and for long life may require pre-processed food; those with only a right-trunk will have greatly reduced energy levels and will be capable of little physical activity). They can even survive decapitation, as most of the body-regulating mental processes take place in organs near the junction of the two trunks – and this also means that if one trunk is amputated from the other, the amputated trunk is still capable of life, and even reproduction (though very rudimentary intelligence).

Cuilco bodies are relatively narrow, and sinewy, though they are less muscular than their unintelligent closest relatives. They are covered with a soft, supple, slightly napped skin – much like a very soft suede. This skin is good at preventing water and nutrients from passing to the outside, despite generally damp conditions – indeed, it can become flaky and dusty if the air is too dry. It is not good at preserving heat – in the generally warm conditions, this is not a priority, and when heat preservation is required it is accomplished behaviourally (through shelter-building and communal huddling).

Cuilco skin is a pale tan or fawn in colour. The skin on their front is somewhat paler; that on their back is slightly darker, and has the suggestion of darker-still stripes, but no more than a suggestion. There is no substantial geographical variation in skin colour. There are slight variations in skin colour and stripe pattern between individuals, and stripe pattern variation in some cases can be linked to subpopulation, but these variations are small and not of significance in cuilco society. Skin also changes colour depending on conditions – it becomes somewhat darker when wet and paler when dry, and may change more dramatically in colour when in contact with certain chemicals (including in the atmosphere), usually only impermanently and without causing lasting damage.

Cuilco reproduce sexually, but individuals are theoretically hermaphrodite. In each individual, the secondary reproductive system is of the opposite sex from the primary, which may be of either sex – that is, primary males are secondarily female, and vice versa. This secondary system is not normally ‘active’, so individuals cannot impregnate themselves; the secondary system becomes active if the primary system is lost or terribly damaged, or in extreme cases of isolation (enabling individuals to impregnate themselves in times of population collapse, or on being stranded on a new island); primary females also have their male system activate when they are close to death from certain kinds of injury or disease.

Males (i.e. primary males) and females (i.e. primary females) are physically all but indistinguishable. Male systems possess a penis, and female systems a vagina, but both are hidden within a closed genital slit, with the penis only being protruded in extreme arousal.

The exception to this indistinguishability is during and after pregnancy. During pregnancy, the skin flushes and darkens, and the belly expands. Motherhood causes the secondary reproductive system of primary females to be temporarily repurposed to produce protein-rich milk, with the secondary penis acting as a nipple – this condition is triggered sociopsychologically rather than biologically, so that if a mother dies a surrogate mother can produce milk. Primary male reproductive systems can also be repurposed in this way, but only once the male’s secondary female system has been activated (i.e. in times of population collapse when the male is having to act as a hermaphrodite).

Cuilco almost always give birth to a single newborn each pregnancy – twins are exceptionally rare. A cuilco female in nature will on average have three or four children in her life, with a large gap in time between each one. Births tend to be (instinctively) co-ordinated into cohorts. In nature, cuilco may live more than a century – in high-technology societies, two centuries is a more common lifespan, with some individuals reaching beyond three.

Cuilco are muscular, but are not particularly physically strong. They are, however, extremely agile and fast-moving.

Cuilco rely primarily on two senses: sight, and echolocation. They are relatively short-sighted, but have excellent colour perception; their large eyes are near the top and the sides of their flattish heads, but are still forward-facing, within forward-facing orbits. Their echolocation is of an unusual type: an ultrasound wave is ‘fired’ forward from the ‘tongue’ (a hollow tube), and the echo is caught in their large, semiconical ears, which project laterally from the skull. The ultrasound is powerful, able not only to travel some distance in air but to partially pass through many thin materials, which enables the sender to ‘see through’ the screens of foliage that block their view – primarily, this sense allows them to determine the solidity of barriers as they approach them, and the size of any vacancies behind those barriers, as well as gauging the solidity of obstacles and footholds, allowing them to choose paths rapidly as they travel. However, the ultrasound beam is tightly directed, and the cuilco must turn its head to redirect it, giving them a characteristic pattern of small, sharp head movements followed by periods of stillness. Cuilco are also limited in the rapidity of the sound generation – due to the mechanism of sound production, they are only able to produce two to three pulses a second. Echolocation is therefore of little direct use in hunting.

A larger problem with cuilco echolocation is the lack of specialisation in the cuilco ear. The same ear is used both for sonar reception and for ordinary hearing (cuilco have accute hearing, important in an environment with limited lines of sight), and neither the organ nor the brain is fully adapted to deal with this duality of function. As a result, cuilco cannot easily analyse both ultrasonic sonar signals and normal sound cues at the same time: thus, when using sonar, cuilco are almost deaf to sound, and when distracted by sounds they become almost deaf to sonar signals, as their brains phase out sounds at (depending on what they are doing) either high or low frequences when concentrating on the other. An additional complication is that cuilco speech is generated in a similar way to sonar, although it is much quieter, and mixes ultrasound with audible (to humans) high-pitched squeeks and clicks. Cuilco therefore cannot use ultrasound when speaking. In any case, the high-amplitude sonar cuilco generate are costly in terms of energy, and their tongues rapidly tire. As a result, cuilco only intensively use echolocation when in motion, and only periodically when at rest – echolocation is not a continuous sense for them, and is used only to gain information about stable elements of the surrounding environment.

Finally, the powerful sonar of cuilco raises the possibility of intentional or unintentional harm. Cuilco have evolved resilient auditory organs so that they are not permanently deafened by stray sonar beams, or their own beams reflected from something unexpectedly close or solid (this is also part of why their brains tune out sounds at these frequencies when not actively employing sonar), but nonetheless they may find these experiences painful and disorienting.

It is also worth noting one more interesting sense that cuilco possess: optic polarisation. Cuilco possess two pairs of ocelli on their snouts, and a fifth, single ocellus between their eyes; these are effectively primitive eyes themselves, but they are incapable of resolving images. Instead, they gauge the angle of ambient light polarisation; in an environment where the sky is often invisible due to intervening foliage, and is often overcast when seen, this sense allows cuilco to judge the likely position of the sun, providing an instinctive sense of direction, as well as contributing to their perception of the time of day.

Next time: Cuilco primitive society

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2 thoughts on “Cuilco: Biology (another alien species)

  1. […] on from my earlier post on cuilco biology, here’s the next installment: on how cuilco lived ‘in a state of nature’, and a […]

  2. […] I: biologyII: primitive and early society III: modern society IV: art, architecture and apparel V: perception by other species […]

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