Not all sub-sentient species resident in Culture habitats were pets living in close proximity to humans and other people much of the time. The Culture maintained vast reserves for wild creatures - the Culture did not really have zoos, with the suggestion of cramped cages and bars separating exhibit and visitor - and preferred to dedicate large volumes to near-perfect reproductions of the animals' natural habitat.
Fortunately, the very widespread use of the Culture's favourite form of habitat, known as Orbitals, meant that this was easy enough to arrange. An Orbital was a splendidly efficient way of getting the maximum amount of usable living space with the minimum amount of matter. A full Orbital was a circular band in space, only three or four thousand kilometres wide but fully ten million in circumference. Admittedly, such a structure was made mostly from exotic super-strong materials and held together mainly by force fields but, if spun so that it turned once in a single day-night period, it would automatically produce an apparent gravitational field of one standard gravity. Such a structure would be placed in an orbit around a suitable star, tilted just off the ecliptic so as to allow half of the Orbital's inside surface to be in sunlight half the time.
Such an extravagant abundance of living space - tens of billions of square kilometres - meant that it really was no trouble to dedicate an insignificant fraction - say, a square Plate four thousand kilometres on a side - to exotic environments that mimicked, for example, the upper atmosphere of a gas giant, or an ice-bound moon, or a scorching hot rocky planet from the innermost segment of a stellar system. Managing the appropriate temperature and atmospheric conditions was of course child's play; only slightly more tricky was getting the gravitational field correct. Fortunately, using artificial gravity to either augment or reduce that produced by an Orbital's spin over an area of ten or twenty million square kilometres was well within the capabilities of the machinery that the Culture could bring to bear.
"Hello, Khat," a deep voice said through Dyderth's terminal, "Hub here."
Culture Orbitals were controlled by a Mind: an immensely powerful AI that oversaw not only the baroque complexity of the operation of the Orbital itself but also took it upon itself to ensure the happiness and wellbeing of all the people thereupon. For maximum efficiency, such a Mind was installed in its own housing located at the centre of the vast wheel of the Orbital and was therefore universally referred to as Hub.
"Hello, Hub," Dyderth replied, "What do you want?"
Khat Dyderth was fussing around the various tanks and vivaria which contained some of the more esoteric parts of his collection, trying to decide which of his specimens would provoke the most interest at the forthcoming club meeting and would likely prove more interesting than anything Malarkii might bring.
Dogging his heels was a white furry animal whose back was adorned with a single oddly-shaped brown-black patch and was therefore known as Ace. The little animal had been his constant companion since childhood. Ace padded back and forth, seemingly content to let its master conduct his incomprehensible actions without, for the moment, demanding attention itself.
"If you are to be on time at the Club," Hub said, "You will need to leave within the next few minutes."
After much deliberation, Dyderth selected a large glass-walled vivarium. The enclosure was mostly filled with sandy soil in which a large colony of eight-legged social arthropods had created numerous visible tunnels and chambers. The carefully-sealed box was warm to the touch, with the upper surface of the soil seared by an artificial light source emulating desert sunshine and decorated by a - mercifully entirely artificial - animal carcase which was being rapidly and skilfully dismembered by numerous members of the colony.
"I'm on my way now," he replied, "Can you get a travel car ready?"
"Sure thing," Hub said helpfully, "It'll be waiting for you when you arrive."
"Great. Come along, Ace."
Long-distance travel on an Orbital was all based on the outside of the ring, open to the vacuum of space and so enabling much higher speeds without that pesky air resistance getting in the way. So it was necessary to go down quite a long way to access the transport levels; essentially, a passage right the way through the super-dense Base material.
Dyderth, tailed by Ace, walked across the courtyard of the rambling estate he shared with his extended family and entered what looked like an ordinary lift. The door shut silently and the lift dropped, accelerating smoothly so that he could feel the increasing speed but not so fast that his internal organs were subjected to any discomfort. The lift slowed twice during the long descent as it traversed a couple of heavy-duty airlocks designed to protect the Orbital's atmosphere under extreme conditions, finally stopping alongside a silvery tubular vehicle apparently embedded in the floor, its wide doors open. Dyderth stepped in and deposited the vivarium on the floor where it was discretely clamped; Ace hopped in and curled up on one seat as if he owned the place; Dyderth himself made himself comfortable on the other chair.
The car's doors shut smoothly and the vehicle accelerated smoothly, disappearing into a tunnel then emerging into the blackness of space. Both sides faded to form transparent windows, showing brilliant stars in one direction and the matt blackness of the underside of the Orbital on the other. All a familiar sight to Dyderth; he barely glanced at the view; instead he settled into a light doze like Ace while the industrious arthropods got on with the task of feeding their queen.
Hub's guarantee was less than two hours between any two access points; as it happened, the distance between Dyderth's family home and the club's grounds was a relatively small fraction of the circumference of the Orbital, so that the journey took rather less than forty minutes. Dyderth and his pets emerged from the travel system via a lift set into a small and rustically ornate building set at the side of the natural - as far as anything was natural on an Orbital - amphitheatre which formed the grounds of the Exotic Pets Club.
The ground was a wide grassy meadow bisected by a meandering stream, crossed at intervals by low bridges, the whole almost completely surrounded by heavily-wooded hills. The sun was high, the air was warm and an eclectic collection of tents and canopies were set around the edge of the paddock rippling in the gentle breeze.
People in groups large and small stood about, most deep in conversation and almost all visibly accompanied by some unusual animal, variously furred or winged or beaked and sporting a range of number of legs, from zero up. Drones slaved to the club's management AI zoomed about the place, delivering an exotic collection of foods and drinks for the humans and an even more esoteric range of substances for the animals.
Dyderth stopped and looked around, Ace waiting patiently at his heel. Eventually, he stopped a drone - one which looked more like a flying salver than anything else - and asked where he could find Mathan Malarkii.
"Mister Malarkii has not yet arrived," the drone replied politely, "But I believe that is him approaching now."
Dyderth was about to ask what the drone meant when people all over the grounds started turning and pointing. He spun around to see a vast dark shape in the air, flapping slowly and steadily in their direction.
Most Culture citizens had sophisticated image processing and vision augmentation subroutines in their eye-brain subsystem. Dyderth engaged his, almost without thinking about it. The dark shape suddenly zoomed closer, now grainy and jittering as the near-instinctive processing struggled to keep the moving image stable. But the view was more than good enough make out Mathan Malarkii sitting on the creature's back and waving energetically in their direction.