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Hollow Moon Planetology: Blue Moon -- Animal Lifeby Sharon Dornhoff
Animal Life in the Hollow Moon
Compared to Ordana's task of adapting plant life to Matera's darkness, her Immortal associates Ka and Seshay-Selene (who took responsibility for terrestrial and marine animal life, respectively) had it easy. The only substantial changes they found necessary at first, to allow Mystara's nocturnal animals to prosper in the Hollow Moon, was to alter certain species' coloration to suit the colour-shifted lunar spectrum, or the dark vegetation against which they'd need to camouflage themselves. Behavioural changes, which would acclimatise them to the moon's constant darkness and lack of seasons, were carefully conditioned into the long- lived vertebrate species, with little alteration to their genetic makeup; for insects and other invertebrates -- which undergo much faster evolution, thanks to their short generation-time -- most could simply be deposited in the HM and allowed to adapt on their own. There are, indeed, animals in the HM which significantly differ from their Mystaran ancestors -- most notably, the siliceous "glass" corals of Mare Foecunditatis and the Vesper Ocean -- but these were introduced to the setting specifically to fill essential biological roles without which the lunar ecosystems would be incomplete: they were never endangered on Mystara, so could be placed on Matera in an altered state.
Like lunar vegetation, many vertebrates in the Hollow Moon look bizarre to Mystarans. Most wild species tend to be several shades darker in colour than their planetary counterparts, to blend in with the black or near-black vegetation that surrounds them; for those animals in which melanism is occasionally seen on Mystara, such as leopards, black pigment is universal among the lunar breeds. In other cases, an animal's dark colour may prove to be an illusion caused by the HM's indigo light: a tiger on Matera would appear pure black, until torchlight or a Light spell renders its orange stripes visible. (Many deep-sea fishes IRL show a similar "false black" camouflage, turning bright orange under divers' lamplight.) In a quirk of Materan adaptation, fishes and marine mammals in the crystal-bottomed seas break with the usual coloration of free- swimming species, in that they are equally dark on both upper and lower surfaces. Since half the time, light in the lunar seas shines up from the seabed instead of down from the surface, having a pale belly and dark back isn't useful for fading into the background (except for a few pelagic porpoises, who've cleverly adjusted to the reversed lighting at fulldark by swimming upside-down! :-D).
Among those animals which aren't dependent on camouflage, either as stalkers who must remain inconspicuous or as prey themselves, lunar varieties tend to go in entirely the opposite direction: they are extremely pale, albino, or even (mostly for invertebrates) bioluminescent. Pale coloration is especially common in those species which constantly live under leaf litter or other cover (e.g. salamanders, moles, centipedes) or whose natural defences leave little to fear from predators (e.g. porcupines, poisonous frogs, hippopotami). Mystaran species which became albino through subterranean living, such as white apes, always retain this lack of pigmentation in the Hollow Moon, even if the perpetual twilight permits them to forsake their cave-dwelling habits.
One feature shared by many lunar animals is bioluminescence -- the biochemical production of light, by means of the firefly-enzyme luciferin, or by harbouring symbiotic, luminous bacteria. While the majority of species introduced to the HM setting used scent or sound to communicate and attract appropriate mates, those which depended upon sight- recognition and/or visual cues were placed at a distinct disadvantage, in their new environment: they either couldn't see each other for courtship purposes, or -- due to the colour-shift effect -- they didn't recognise members of their own species, when they saw them! In order for those animals which depended on visual signals -- red, orange, or yellow cues, especially -- to perpetuate themselves in the Hollow Moon, the Immortals Ka and Seshay-Selene had to borrow Ordana's trick of adding modified symbiotes to an existing species, without changing the hosts' genetic makeup. By daubing a crop of luminous bacteria onto an animal's body, and adapting these bacteria to transmit themselves from generation to generation, the two Immortals could give a visually-oriented species clear, distinctive markings by which to attract a mate, warn predators of its venomous nature, and communicate with its own kind though behavioural displays and body language. Markings that, rather than being cloaked in twilight, actually glowed in the dark! Patches of brightness could be placed on parts of an animal which might be covered for camouflage purposes, as with a frog's inflatable throat-pouch, or could be designed to glow only during the breeding season and remain inconspicuous throughout the rest of the year. Because the bacteria would generate their own light instead of reflecting ambient light, any colour of markings could be selected, the better to conform to each animal's expectations of what a member of its own species "should" look like.
Had the HM's Immortals stopped there, having restored lunar animals' ability to signal their mates, Matera would probably be a very gloomy, drab place -- black vegetation, black or pale animals, and only half the usual number of colours to its spectrum. But things didn't end, just because the moon's moths, fishes, and other sight-oriented species were once again able to tell each other apart. Simply put, the very idea of glow- in-the-dark animals turned out to be so marvellously-captivating to Seshay-Selene (who was still relatively new to her Immortal powers, when she joined the HM's "design board", and who'd never created life before), and so appealing to Korotiku (since spiders were one of the taxa which had thus been enhanced), that these playful Immortals promptly made a game of creating hundreds of unique, luminous species for the lunar environment! The Immortal whale quickly filled the seas with glowing varieties of nearly every marine animal taxon, while Korotiku -- who'd been rather stifled by Ka's stolid insistence that the Hollow World conform closely to existing ecosystems, and was delighted to exercise some creativity in this novel environment -- happily usurped the Preserver's role in populating Materan lands with arthropods, devising bioluminescent arachnids, myriapods, and insects of all kinds. The dinosaur-Immortal nearly threw a hissy-fit, at seeing HIS idea (!) for the museum-worlds being taken off in such a frivolous direction -- creating brand-new lifeforms had never been a part of the plan! -- but Ordana was grateful for ANY addition of light to benighted Matera, by that stage, so Ka's objections were decisively voted down.
The practical upshot of all this is that, while the vegetation of Matera is drab and foreboding, its insect and marine life are anything but! Normal-coloured invertebrates certainly do exist, having been brought there for their own protection, but they are far less noticeable than the multicoloured swarms of luminous moths, flies, beetles and crickets which flutter and hop through the air, or teem upon the ground. Spiders with brightly highlighted leg-joints stalk brilliant, gleaming silverfish on the forest floors; ants wave light-tipped antennae to one another, as they tend their shining herds of aphids; even lowly cockroaches expose striking, colourful patterns, when they spread their wing-covers. In the seas, glowing coral reefs harbour scintillating representatives of every known animal phylum, from sponges to stingrays to ammonites. Even Ka eventually came around, gifting several venomous amphibians and reptiles with glorious, shining patterns that warn predators of their toxicity! All of the vibrancy and attractiveness which is so weirdly absent from the dusky, pale-flowered lunar plant life, is stunningly displayed by Matera's cold- blooded animals ... the same animals that are so often dismissed as "icky", by the uninitiated. The simple fact that arthropods are some of the most beautiful things in their world has had a marked effect on how Materans view such creatures; it's no fluke, that this is the one place in the Mystara- Patera-Matera system where aranea are an accepted and open part of society, or that lunar folk eat by choice many things which Mystara's Graakhalians eat by necessity. :-)
Unique Materan sea life
Nowhere in the Hollow Moon is the diversity of bioluminescent life more evident, than on the coral reefs of Foecunditatis. In nature, corals are restricted to shallow waters because they are dependent on sunlight: each tiny polyp harbours photosynthetic algae within its body, and cannot survive for long without a source of light*. Ordana's alteration of these algae to make do with lower light-levels went part of the way toward letting coral adapt to the HM setting; but, unfortunately, it wasn't enough. The long periods of deeper darkness, when sunlight shines on the Nearside instead of the Firmament, were too long for the delicate, calcareous corals of Mystara to cope with. This posed a real quandary for Seshay-Selene, in her efforts to populate the seas of Matera with life, as coral reefs are vital habitats for an enormous variety of marine animals and algae. Moreover, even if they could be adapted to live in darkness, the opaque masses of calcium carbonate which coral-polyps lay down, in building a reef, would've cut off all incoming light from beneath the sea floor, at fulldark ... a source of illumination, for growing algae, which was equal to if not greater than that light which struck the waters from above!
[* - This is one of the reasons divers near coral reefs are discouraged from kicking up sand from the bottom -- it coats the polyps and deprives them of light.]
From the beginning, the problem of keeping the sea floors clear of debris and silt had been a serious concern, for the Immortal whale; if too much material blocked off fulldark's sunlight from beneath the Maria bedrock, half of the available energy for underwater ecosystems would be lost. In the Vesper Ocean she was able to create powerful currents to wash such sediments into massive submarine dunes, leaving large areas open and illuminated, but the other seas were too small to accommodate such complex dynamics in their depths. For tiny, rain-fed Mare Crisium, reducing the mineral content of the water served to discourage silting, but all of the other seas were fed by sediment-rich rivers that would soon coat their bottoms with muck if she let them be. She never did find a good solution for Mare Humorum, which remains murky and relatively unproductive to this day (fortunately, its shark-kin inhabitants don't mind these conditions).
The solution came to her at last, when she took a break from pondering this dilemma and examined another form of stationary marine life: sponges. Glass sponges, that is ... a kind of sponge which builds its skeleton out of tiny rods of clear silicon. And what worked for sponges' skeletons, she suddenly realised, could surely work for corals', too! Whereas normal corals construct their underpinnings out of white calcium carbonate, a siliceous skeleton would be completely transparent: able to admit light from beneath, as readily as from above. Slight modifications to the refractive index of a polyp's skeleton could be made, during its growth, so that incoming light-rays would always follow the path of a coral-branch to its end instead of spilling out; in effect, it would pipe light from the crystal seabed directly to the coral animal's algal symbionts, like a fibre- optic cable! Once such a reef had been laid in place by Seshay-Selene, it could even counter the process of sedimentation by growing ever-taller, as each branch of coral extended itself to rise above the silt-line and the ever- growing glass pillars from which they sprang piped fulldark's sunlight up through the muck in which they'd become embedded. If a branch should be broken off above the sediment, kelp or similar large algae would quickly claim the projection's still-glowing tip as a holdfast, until such time as new coral polyps became established. Most importantly, by laying several yards of silicon "branches" and sediment between the crystal seabed and a reef's life forms, this would raise the Hollow Moon's coral communities well clear of the terrible cold that restricts the HM setting's benthic organisms to sand-crust islands, and the underwater basalt-shelf offshore of the Apennines.
Inspired by this idea of crossing sponge and coral biology -- which proved phenomenally successful; in fact, the whole of the Mare Foecunditatis seabed is covered with glass corals, as are parts of the Vesper Ocean and a few spots in Humorum! -- Seshay-Selene then tackled the problem of Mare Tranquillitatus: a habitat, which also needed to retain its clear, light-permeable seabed; yet which, although it adjoined Foecunditatis, she'd planned to set aside for pelagic species rather than reef-dwellers. Since combining the features of two different animals had worked out so well the first time, the cetacean Immortal used the same technique ... but with protozoa instead of animals. Borrowing from the biology of amoebas, shell-bearing foraminiferans, and cold-resistant strains of OD&D/AD&D jellies and puddings, she created the giant forams: barrel-sized amoebas which could consume organic sediments as well as living prey, could endure the chill of the crystal seabed, and which constructed hollow shells (called "tests") for themselves out of rubble, pebbles, and sand. These mindless bottom-dwellers would constantly scour the depths clear of edible silts, while scrounging bits of inorganic debris to cement into their tests; when a giant foram died, its test would provide housing for crabs, octopi, morays and other cavity-dwelling creatures. Every few years, all of these giant foraminiferans would abandon their usual (asexual) method of reproduction, congregate by the millions in a few Immortal-chosen locations, and each break up into dozens of small amoebae that could merge with others of their kind in a mass reshuffling of genetic information ... leaving their tests behind, in immense mounds, while the resulting offspring set out to once again scour the sea floor for stones and sand-grains*. Whole islands have been known to form on Mare Tranquillitatus, over centuries or millennia of giant- foram mass matings, by this process.
[* - Foraminiferans IRL really do have a life cycle like this; contrary to popular impression, not all one-celled organisms are ignorant of sex! ;-) Giant forams encountered by PCs can be treated as scamilles for the purpose of game-stats, although they are not intelligent. Encumbered by their tests, they can't move from place to place fast enough to warrant a movement rate in combat, and if they fail a morale check they cease attacking and withdraw all their pseudopods into their cemented shells (giving an effective AC of -2). They take half damage from cold-based attacks. Giant forams' tests may incorporate bits of metallic or stony treasure, gathered from sunken ships or scrounged off the sea bottom, though this is rare in the extreme. Giant forams are solitary except when they gather to mate; if one is killed, others nearby will neither notice nor care.]
Having assured the Hollow Moon's seas would remain illuminated for the next million-odd years -- eventually, silt would fill Mare Foecunditatis and the giant forams' tests would pile all over Tranquillitatus' floor, but she'd have plenty of chances to fix that when the time came -- Seshay-Selene went on to populate them with dark-adapted sea life of all sorts. In addition to mundane and luminous animals*, Matera's marine habitats are home to sea snails and chitons as big as watermelons, which help clean algae off the gleaming corals' branches; giant scallops with transparent "windows" in their shells, that let in light for symbiotic algae; bizarre, bloated cephalopods called "vampire squid" that seem halfway between squids and octopi; horseshoe crabs that swarm Vesper Ocean beaches during circle tides; and silly-looking pycnogonids (called "sea ticks" by Materan sailors) that seem to be all legs and no body. Among fishes, virtually all of the same kinds are present as one might encounter in the Mystaran seas, although those which can detect electrical impulses -- sharks and rays, sturgeons, electric eels, etc -- are at a distinct advantage, in the unending darkness. Benthic fishes are confined to areas where the crystal is covered in sand-crust, silt, or solidified lava. Adventurers expecting to find prehistoric reptiles in the HM seas, as they have in the Hollow World's, will be in for a disappointment: only one ichthyosaur (Ophthalmosaurus, an 8-HD creature) from the fossil record has the kind of large eye-sockets that imply it might have been a night hunter. Sea turtles and flippered crocodiles, some of them truly enormous, are found on the moon, but sea snakes and marine iguanas find the habitat far too chilly to survive there. There are several species of non-sentient, primitive toothed whales in the Vesper Ocean, along with various seals, tuskless walrus, and a few polar bears on the ice-flats of the sea's frozen outer rim. Great auks and skuas -- veterans of the dark arctic winters -- also congregate on the ice, but most seabirds are absent.
[* - In the seas of the Hollow Moon, this group includes -- but is hardly limited to! -- sponges, anemones, jellyfish, comb jellies, flatworms, nudibranchs, cephalopods (mostly ammonites, squid and octopi), bristle worms, shrimp, crabs, sea cucumbers, brittle stars, feather stars, sea squirts, skates, eels, many reef-dwelling fishes (to match the glowing corals!), sea turtles, and more kinds of zooplankton -- some of them, also housing symbiotic algae -- than a druid could classify in a year.]
Two other habitats should be mentioned here, namely Mare Nectaris (freshwater) and the hydrothermal vents of the kopru. While most life in the lunar lakes and rivers are Ka's and Korotiku's doing, Seshay-Selene also took steps to ensure that Nectaris' crystalline bottom would remain relatively clear of muck. There, gigantic but harmless flatworms rendered cold-resistant by the Immortal whale slither over the crystal, slurping up organic material and shovelling debris out of their path. Hence, the floor of Nectaris is a mudflat that's cris-crossed with streaks of open bedrock, and these ever-changing trails let in enough light to promote algae and a lake-bottom ecosystem of archaic armoured fishes (gars, suckers, etc), mussels, giant crabs (many of the self-camouflaging "decorator crab" sort), giant leeches (which look exactly like the harmless giant flatworms, at first glance), and giant crayfish. In the subterranean hot springs of the Stofler-Walter-Purbach-Arzachel mountain range, giant clams and tubeworms which cluster round the spewing "black smokers" use chemoautotrophic bacteria to live on hydrogen sulphide, and these in turn provide nourishment for the kopru and a bewildering array of intermediate lifeforms... many of them extinct throughout the rest of the world, long before the Hollow Moon or even the dinosaurs ever existed. Slithery giant hagfishes, and relict trilobites unseen beyond the vents since the Cambrian, are among the least-alien of these freakish fossils come to life.
Land animals of Matera
Compared to the Hollow World, the vertebrates of the Hollow Moon's land areas aren't terribly impressive. Most of the larger herbivorous dinosaurs, judging by the size of their eye-sockets and lack of evident specialisation for hearing or smell, were day-feeders; and without such massive prey to feed upon, the big meat-eaters like tyrannosaurids and allosaurs are out, too. (Besides, they've already been assigned to the HW setting by TSR ... so if I want to stay consistent, with that product, I'll HAVE to assume they were diurnal! ;-D) Many of the smaller carnosaur varieties, however -- especially those sickle-clawed "Jurassic Park" superstars, the raptors! -- would've been quite capable of surviving on such "small game" as deer, cattle, or hippos, so aren't dependent on the presence of sauropods and the like, to make a living. On top of that, raptors in the movies have already acquired an image as night-hunters ... and the fact that they were never placed in the Hollow World by TSR, as their big cousins were*, supports this view for Mystara's dinosaurs. And let's face it: Velociraptors are COOL! So, they're among Matera's top carnivores on land, with their different known varieties ranging from turkey-sized -- which is still big enough to attack hin or small livestock -- to the size of a black bear. (One even larger species which hunts in pairs -- some specimens growing as massive as tigers -- exist in the deepest wilderness, but Materans know nothing of them: they'll be every bit as surprised as the PCs, to meet one!)
[* - Sure, nobody but a few palaeontologists even knew that Deinonychus & kin existed, back when the HW set was published ... but, hey: finders, keepers! Allston missed his chance, so I'm takin' them! Nyaah, nyaah, nyaah! ;-D]
Other dinosaurs familiar to Materans include some rather drab herbivores called fabrosaurids, several ostrich-like omnivores related to the sickle-claws, and a whole bunch of coelurosaur species -- pint-sized carnivores, ranging in size from that of a chicken to that of a deer -- including a giant domesticated variety (also known to Mystarans as the so- called "Rockhome lizard") which can be ridden. One armoured genus, Scutellosaurus, is present in the western forests, but it lacks the weaponry of HW ankylosaurs and stegosaurs and is inoffensive and timid. Two kinds of segnosaur -- picture a bipedal, dinosaur version of an aardvark, complete with long foreclaws for ripping open termite nests and simple, peg-like teeth -- pose a threat to the region's giant termites and the aardovai who depend on them; but dinosaurs as a rule aren't the major problem that they are to HW races: only the raptors offer a substantial danger to human- sized travellers, and they are cunning* enough to have learned not to attack armed humanoids ... unless they've clearly got them outnumbered or can catch them off-guard.
[* - None of this "dinosaurs were dumber than rocks" nonsense on MY watch, thank you! Raptors are semi-intelligent pack hunters, just like wolves or lions, and have a similar skill at choosing and bringing down their prey. Even the herbivorous dinosaurs are of animal intelligence -- they were certainly as smart as crocodiles, if not more so, being closer to birds than crocs are -- and the omnivores are nearly as bright as raptors.]
Pterodactyloids such as Pteranodon aren't heavily represented in the HM, as most of them have already been assigned to the Hollow World and must thus be presumed diurnal by default. (This is ironic, as they're the younger branch of the flying reptiles and lived side-by-side with birds, so were more likely to have become nocturnal than their predecessors, in order to avoid competition with feathered flyers!) A much older group of pterosaurs, the long-tailed rhamphorhynchids, does have many representatives on Matera, filling many of the ecological niches normally occupied by day-flying birds. None of them grow particularly large, except those which share the roles of seabirds such as gulls or albatross; the Apennines are home to the largest (3 HD) of these leather-winged flyers... not counting the pteryx, who are fully sentient. Skinwings from the shadow-elf caverns were introduced to the Hollow Moon, along with their vesper elven masters, but these domesticated pterodactyls have failed to establish any feral populations and exist only in captivity.
Among other extinct reptiles, there are large numbers of crocodylians in the Hollow Moon, many of which are quite different from their modern relatives: there are bipedal crocs, long-legged crocs built for running on land, and even a few slender, arboreal species (look up "Sphenosuchia" in a palaeontology text, if you think I'm kidding here...). Most have shorter snouts and less dermal-bone armour -- hence, a poorer AC -- than our present-day gators and crocs. Giant varanoid lizards, including the tremendous and rapacious Megalania from the Pleistocene of the Wallaroo grasslands, are able night-hunters and can be found in the eastern deserts and savannahs. None of the older, Triassic reptile taxa appear in the Hollow Moon -- or the Hollow World, for that matter! -- because they were already long extinct when Ka (a Jurassic megalosaurid) was born, so never had the chance to be preserved.
Less-exotic herpetological specimens are much more abundant than dinosaurs, on Matera. Frogs, toads, salamanders, and caecilians (which are legless amphibians, not worms as the MMC implies) thrive in the dim light and humidity of the midlands, some of them becoming giants; HM travellers can hear toads, treefrogs, peepers and bullfrogs chorusing non- stop, all year round. Toxic varieties of frog or salamander are often luminous, as an extra warning for predators not to even think about it. Nocturnal lizards are common, especially geckos and chameleons, in both normal and giant varieties. Tortoises and freshwater terrapins are neither more nor less common than on Mystara, though several archaic, soft- shelled species exist in the swamps and marshes that are extinct on their planet of origin. Conventional crocodiles, alligators, caiman and gavials are present, along with their non-aquatic predecessors I'd already mentioned. Snakes, especially heat-sensitive pit vipers such as rattlesnakes, tend to do very well on the moon, as rodents and other small- mammal prey are superabundant.
Birds aren't nearly as successful in Matera's darkness as reptiles or amphibians, with the obvious exception of owls. Nightjars, whipoorwills, and other members of the goatsucker-taxon do well in the moon, and there are quite a few nocturnal grouse, quail, ptarmigans and woodcocks. Rails and night herons wade the lunar streams and shorelines, and one crepuscular roadrunner keeps the snake population of the Sohktar deserts in check. The flightless Dark Jungle cassowary -- long extirpated from the Orcs' Head Peninsula, by the humanoid tribes' careless overhunting -- has been given free reign in the midland forests, where few predators dare challenge its formidable claws and legendary temper. A few of these fierce ratites are actually tamed as steeds by the hin of Shaergarde. Piranha birds also roam the midlands, but are seldom encountered; many of them -- the red, orange, or yellow members of their multicoloured flocks -- sport luminescent feathers! One small glade in the heart of the Wallaran dreamlands, yet cut off even from that mysterious region by steep cliffs or deep chasms on all sides, is home to giant kiwis and the giant earthworms they sniff out.
Mammals in the Hollow Moon include many, many archaic or ancestral species from the Age of Reptiles... virtually all of which will look like ordinary shrews or rats, to adventurers. Indeed, most can be considered either rats or -- for the bad-tempered kinds -- giant shrews, if game-stats are called for. Many of these primitive mammals have a mildly-poisonous saliva, comparable to that of an AD&D large centipede, for use in incapacitating insect prey. A few have spiny coats like a hedgehog's. Some lay leathery eggs like a reptile, while others bear live young. Very few grow any bigger than a squirrel. The largest group of these animals are called multituberculates by palaeontologists, and they're of interest to HM gamers for just one reason: they've got the most efficient set of all-purpose gnawing/shearing teeth of any vertebrate that ever lived, enabling them to chew their way through leather, cloth, wood, or thin metal more quickly than your PCs will ever believe! Should a character accidentally set a backpack down on top of a multi's burrow-entrance, OR leave anything that smells of food, grease (including freshly-oiled weapons or armour), sweat, or blood out where these little suckers can get at it, rest assured it's going to have holes gnawed clean through it in a matter of minutes. (And your players thought giant magpies were annoying...! ;-D) The largest of these antique mammals, and one of the most irascible, is the heat-loving ash crawler of the volcanic uplands, an animal which was brought to Matera when its appalling stupidity seemed guaranteed to bring about its extinction. Regrettably, its relocation proved premature; these distorted beasts still exist on Mystara.
Besides these ancient pests, Matera is home to plenty of familiar mammals ... familiar to your players, that is. Unless someone is playing a Wallara, the nocturnal marsupials of the Wallaran dreamlands -- sugar gliders, wombats, tree kangaroos, thylacines and devils -- will look downright bizarre, even before they encounter giant Pleistocene specimens like the bear-sized wombat Diprotodon! Bats are, of course, ubiquitous in the Hollow Moon's skies, as their echolocation gives them an unbeatable edge over other flying vertebrates' sensory abilities; flying foxes fill the role usually claimed by fruit-eating birds, in lunar ecosystems, while other bats pollinate flowers, fish, catch frogs or mice, and consume insects by the ton. Giant vampire bats are present in the moon as well, being found in the margasta rain forests on the isthmus of Foecunditatis/Tranquillitatus; but these are of an extinct subspecies which has yet to evolve the OD&D bats' paralytic powers, and must feed by stealth as IRL vampire bats do. Stirges are also found on Matera, mostly in valleys of the southern humanoid tribelands. Primates aren't widespread in the HM, but there are big-eyed owl monkeys in the margasta forests, and prosimians -- lorises, bushbabies, lemurs, and tarsiers -- can be found throughout the subtropical midlands. Anteaters and armadillos are present, but rare, and the Megatherium -- a crepuscular animal, active at dusk and dawn, on Mystara ... therefore, preserved in BOTH the HW and the HM settings! -- is the only sloth. Pangolins and aardvarks, along with segnosaurs, are much more likely to prey on Rheita termite nests; the former animals sometimes occur as a giants, and although they seldom attack humanoids, their heavy armour- like scales (AC 2, HD 6) makes them tough to drive away.
The herbivore side of the Mammalia is somewhat lopsided, on Matera; while there's oodles of rodents, rabbits, and primitive intermediates between these two taxa, larger hoofed animals are actually quite scarce. Some of the more interesting lunar rodents include giant porcupines, giant beavers (which have an Intelligence of 4-6, and might well be the ancestors of the Serpent Peninsula's mugumba mud-people), and the trapper-prized giant chinchillas of the lunar Alps. Just about any rodent you can think of is found in the Hollow Moon, except diurnal (non- flying) squirrels and -- believe it or not -- common species of rats or house mice ... animals which will never become "endangered species", as long as Mystaran civilisation exists! (OTOH, there are plenty of Materan field mice, and rats other than Rattus rattus, that make pests of themselves in the same way.) Apart from rodents, and a few timid, cat-sized primitive browsers called condylarths, the only plant-eating mammals that can really be considered common in the HM setting are deer -- including the hardy reindeer of the crystalbarrens, as well as several woodland and upland species which grow no bigger than North American white-tails -- and noisy, gregarious herds of peccaries. There are hippopotami, some of them giants of their kind, in the Rheita rivers and the marshlands of the Rilles; they are the largest mammals on Matera apart from primitive whales, as there are no elephants, rhinos, or sea cows. A few shy vicuna have been spotted in the lunar Alps, and a number of tiny, tusked ruminants such as chevrotains forage in what little underbrush the vesper elves' lands have to offer. Mountain goats and musk oxen are the only wild bovids in this grass-poor setting, although some of the domestic livestock kept by Materan humans are of species which can no longer be found on Mystara and were provided by the Immortals as a way of preserving both them and their human caretakers, e.g. the kouprey -- a type of wild jungle cattle, which went extinct IRL less than forty years ago -- raised in place of common cattle, by the natives of Deslandres. Tapirs are the only perissodactyls in the Hollow Moon, and unlike the "swampmares" of Ator they cannot be ridden (not even by a gator man).
Virtually all the mammalian carnivores can be found in the Hollow Moon, except for some of the largest species (lions, smilodons, cave or grizzly bears) that would suffer from the scarcity of large herd animals to prey upon (such animals are sent to the Hollow World instead). While classic "sabre-toothed tigers" are too large for the lunar habitat to support, its lightweight relatives such as Machairodus can live there; such cats have 1 HD less than Smilodon and do -1 hp/die for damage (minimum of 1 hp per attack), but can run half-again as fast as their bulky HW counterparts. Immense hyenas with twice the HD and bite-power of spotted hyenas hunt the Rheita savannah, having much the same enmity and rivalry with sickle-claw packs as their smaller relatives do, with lion prides. A few truly bizarre meat-eating animals called mesonychids -- built like bears and dire wolves, but actually sporting hooves (!) like the herbivores to which they are related -- have found a unique niche for themselves as the only predators which can traverse the crystalbarrens unharmed: their hoofed feet can contact the heat-leeching crystal without damage, something no canine or feline paw can endure! Because their habitat is one of the only ones in the Hollow Moon where ordinary (i.e. hoofed) herd animals can out-compete giant insects, mesonychids grow much larger than other predators native to Matera; one of them -- the awesome (and incredibly ugly) Andrewsarchus* -- is a 9+9-HD, man-eating nightmare on legs, and the largest IRL mammalian carnivore that every walked the earth. Immortals help the party which runs into one of THESE snaggle-toothed throwbacks, in the middle of a frigid and featureless wasteland where THEY'RE the only fresh meat for miles! Among the more fantastic carnivores, night-sighted owl bears can be confronted everywhere on land (including a big polar bear/snowy owl subspecies, in the Mare Frigoris region); primitive displacer beasts which lack the displacement power of modern strains (which might cause PCs expecting the normal variety to strike at thin air, in itself!) prowl the mountain slopes, like great tentacled cougars, in kopru territory; and eerie packs of yowlers stalk the unwary, through the black pine-woods of Stygia.
[* - Check "Back To The Age Of Mammals", Dragon #167, in the back-issue files of the TSR website for Andrewsarchus' AD&D stats ... and disregard the part of the description that says it's mostly a scavenger. We'll probably never know what the IRL animal's feeding habits were, but the ones living on the crystalbarrens of the Hollow Moon are full-time hunters! ;-) Stats for Megalania, the giant varanid lizard of Pleistocene Australia (and the HM Wallaran dreamlands), and the giant hippopotamus are also available in the same article.]
So with so many mammals missing from the fauna one might expect on Mystara, and herbivores especially being limited in size and diversity, how can the carnivores of the Hollow Moon -- not to mention the people! - - possibly find enough to live on? The answer is simple: Giant bugs. While IRL insects are limited by their size as to which animals can prey upon them, the giant varieties of insects, arachnids, and other arthropods which appear in so many AD&D/AD&D settings as cannon fodder have actually become the keystones of Matera's terrestrial ecosystems. With their multiple sensory systems other than the visual, the ability to see by the ultraviolet light which makes up a major fraction of the Firmament's total radiance, and a metabolism which allows them to go torpid during periods of poor foraging, yet live on very few calories for their size, arthropods turned out to be better-adapted to the Hollow Moon than the mammals and reptiles with which they coexist.* While the various "monster books" for games invent giant-sized versions of only those arthropods which pose a potential threat, lunar explorers should come across just as many placid or harmless varieties (which I'm not even going to begin to enumerate; pick up any book on insects at your local library, and you'll have literally THOUSANDS of choices! :-D) as dangerous or aggressive ones. In fact, any time a roll for wandering monsters comes up negative in the Hollow Moon, don't just tell the players that nothing much has happened: Throw a bug at 'em! (Harmless, of course... but don't tell them that! ;-D) And don't forget, most lunar insects have colourful bodies that glow in the dark, so even an obviously-inoffensive insect should draw their attention and (dare we hope...?) invoke a sense of wonder.
[* - For another reference, look up "Bugged About Something?" in Dragon #174, also available in the TSR website's back-issue files. It's got plenty of reasons why giant insects might tend to have an edge over vertebrates -- in physique, sensory capacities, and hardiness in the face of cold weather -- as well as some nasty tricks to pull on players who think "humble" insects have gotta be pushovers. :-)]
Since insects and their relatives, the crustaceans, arachnids, and myriapods, are so prominent in the HM ecology, it's not surprising that many Materan societies have learned to tame and -- to the limited extent that it's possible -- train these versatile animals. Aranea are able to live openly in lunar communities, since the majority of people born on the moon consider spiders neither ugly nor needlessly-hostile, and the arachnids have devised simple signals by which they or their phanatrel servants can control unintelligent giant spiders, giant harvestmen, and rhagodessas. (All the types of non-magical giant spider from the OD&D rules or Creature Catalogues can be found on Matera, although only the aranea themselves are sentient.) Giant centipedes have a keep sense of smell and are uninhibited by darkness; these creatures are sometimes used as trackers by forest goblinoids, or by thief-takers with the Cynidicean police. Giant velvet worms -- not arthropods, but an ancient lineage from which the arthropods evolved -- have the ability to spit a quick-setting adhesive at prey or targets designated by their trainers, and the vesper elves eagerly seized upon these many-legged near-worms as a safer alternative to shroud spider webbing, when they have a need to capture someone alive. Giant ambush bugs, squat armoured insects with a venomous bite (save vs Poison or the bitten body part is incapacitated by searing pain), can't really be "trained" as such, but are often set as watchdogs over valuables or entryways, as they'll remain in place for days on end awaiting a trespasser and may attack with a +4 to hit it they achieve surprise.
Other arthropods are raised as livestock by Materans, for the products their bodies have to offer or the benefits they provide. Giant millipedes -- placid herbivores that subsist on spoiled plant matter and fungi -- are "sweated" of the defensive compounds they secrete (including cyanide), for use in pest control and alchemy; using these compounds in warfare isn't unprecedented, but is reviled as the HM equivalent of dropping nerve gas on the enemy (plus it's expensive! ;-P). A smaller variety of giant millipede produces no toxic "sweat", but has barbed bristles on its posterior which can be broken off harmlessly, and used for everything from combs to gaffs to crude weapons (1d3 hp damage) to hooks for hanging up one's garments. Soft, flat-bodied giant silverfish are bred for leather, as their smooth, supple hides can be kept flexible after skinning with applications of the extract of giant beetle pupas; the thick forewings of fire beetles, also raised for their light-organs, are cut and fitted for armours (as scale mail). Giant aphids are milked for nectar, and shorn of the fluffy white "wool" on their abdomens, that's the closest thing to goose down available in the Hollow Moon. Giant ichneumon wasps are reared for pest-control purposes in most lunar agricultural regions, though this practice is highly illegal within the land of Aran. The Cacklogallinian trade-cities cultivate giant glowworms and fireflies for their luminous body fluids, and Modrigswerg alchemists isolate the active enzymes of bioluminescence from these, for long-term storage and future use. Giant bees have been imported to the setting by the Cynidiceans, who domesticated them long ago, but there are very few flowers in the Hollow Moon which are of interest to bees and the honey they produce is often of inferior quality; there are bees -- even giant forms -- native to Matera, but these are luminous solitary bumblebees and of no value as honey-makers (lunar beeswax is good enough, OTOH). Pupas of giant moths are unwoven for silk, although it's a coarser, cheaper fabric than that which aranea or domesticated giant spiders can produce.
A few insects aren't bred, but are hunted for their useful body parts, or because they're agricultural pests or just plain dangerous. Giant dragonflies -- enlarged versions of the mundane insects, not the breath- weapon-spewing/MMC monsters -- are killed for their wings, which are used much like window glass, and to prevent their attacks on livestock and lone persons. Giant wasps -- another luminous taxon -- have a bounty on them in Old Aran, as the aranea have a petrifying terror of these deadly spider-hunters. Nests of giant ants are exterminated without mercy, for the ability of such creatures to pick clean whole acres of farmland and to render towns and villages unlivable has been learned through generations of bitter experience. Matera's two-foot-long giant cockroaches are likewise regarded as vermin, but are at least put to good use as animal fodder for Rockhome lizards, peccaries, and other arthropods; their wings, if prepared through a lengthy procedure only the Taurus gnomes are able to make head or tail of, much less understand (!), can be reduced to fibres, mashed, soaked, pressed, dried, and at last converted into a serviceable substitute for paper. Scorpions of all sizes are hunted for their venom -- another alchemical substance the Modrigswerg pay dearly for -- and for their unique (and IRL!) property of phosphorescence: while many lunar arthropods glow, scorpion-chitin absorbs UV light and releases it as blue light, and will continue to do so for weeks or months after the animal dies, whenever it's exposed to the Hollow Moon's ambient ultraviolet. The glow itself is too dim to see by, but the chitin has many ornamental and decorative uses.
Last but not least, Materans of all races breed and rear giant insects for -- C'mon, you knew this was coming! ;-D -- food. Yes, folks... the only thing a Materan would find disconcerting about a fancy court dinner in Herath, would be the fact that everyone's expected to sip their giant flies through a straw! Okay, so it's not THAT bad (quite). But insects are a principle source of protein in the diet of most HM people, humans and demihumans no less than aranea or aardovai. With the exception of giant cockroaches which are considered too filthy in their habits, and giant ambush bugs which taste absolutely terrible, all of the arthropods mentioned above are eaten, as well as "sweated", "milked", shorn or skinned. Giant cave crickets (aka giant locusts) are also farmed specifically for their meat, and for their egg cases which are cracked and cooked just like birds' eggs, or else dried and carried on journeys as lightweight, nutritious iron rations (not unlike beef jerky). Giant termites are not only the mainstay of the aardovai diet, but they actually become ill and die if unable to consume their preferred and necessary isopteran prey! Other insects -- giant versions of lacewings, mayflies, cicadas and caddis flies -- are even considered exotic delicacies, as they are very difficult to rear, or are available for consumption only at specific times in the course of the lunar year. By comparison, the phanatrels' appetite for farmed freshwater crabs and crayfish, which they raise en masse in Mare Nectaris, seems pedestrian ... yet even they won't pass up a choice platter of stonefly, with sweet broiled aphid-nymphs on the side.
In fact, that's the thing that's most likely to catch Mystaran PCs off- guard ... not the fact that Materans eat insects, centipedes, and other creepy-crawlies on a regular basis; but the fact that they actually prefer them, to so many other foods which are available. Vegetables and fruits in the Hollow Moon setting aren't that much to get excited about -- the fact that they're all the same dull, boring black might have something to do with it -- and mammalian livestock is usually considered too valuable, for milk or wool, to squander on a one-shot meal; plus, it takes a lot longer to grow a calf into beefsteaks, than to hatch and grow a giant locust into cricket-meat pies! But moreover, Materans have realised what most of the world beyond the developed nations of IRL Earth has never forgotten: insects, properly prepared, can taste pretty darn good, easily holding their own against most common staple foods available to Materans or to commoners of Mystara. And considering that, if it wasn't for insects as fast-breeding, cheap-to-maintain, high-protein livestock, lunar peasants and labourers would be stuck eating black bread and potatoes like every other poor person in a pre-modern society, they've got it pretty darn good, themselves.
So go ahead and gross out your players, having their friendly HM hosts feed them whatever multi-legged critter's going to sound the most nasty... and then tell them it's the best thing they ever ate. Who knows...? Maybe next time their PCs find a giant beetle scarfing the last of their food supplies, they'll realise there's a more practical solution than trudging clear back to town for a re-stock.
After that, of course, you can have their henchman who didn't follow them to the moon go on and on and on about how he can't believe they actually ATE that disgusting bug.... ;-)