When the colonists came to Pern they found a host of native creatures, many of them sporting six limbs in one form or another. They also brought along several species of Terran stock which were adapted by genetic alterations to Pern's environment.
When the E.E.C. first explored PERN, they were surprised to see no evidence of any large mammalian creatures, however they did discover fossil remnants of a herbivorous Ruminant in a tar pit that was 50,000 years old.
- Fire lizards are 4-legged and 2-winged reptiles, and along with snakes and wherries, share the same common ancestor. They are divided into five colours, as are the dragons: Gold, Bronze, Brown, Blue, and Green. The Golds (or Queens) possess greater intelligence than the other colours, and unlike the foolish greens, will lay their eggs safely above the tideline of the beaches where they tend to live. Fire lizards can, like dragons, be Impressed by humans at hatching, but unlike dragons, those that don't Impress stay wild and don't go between to die. Fire-lizards are telepathic and communicate with their owners, though only through images, unlike dragons, who can communicate verbally as well. Fire-lizards that were treated with the mentasynth enhancements by Bay Harkenon tended to be smarter and more capable of communicating with their owners.
- Snakes are reptilian vermin that infest Pern. Unlike Terran serpents snakes posess six limbs which some use to burrow and dig. Others are adapated to survive an amphibious life, with either webbed feet or paddles. Only a few species of tunnel snakes are edible, as the colonists learned early on. Some species also have a venomous bite, that could prove fatal if left untreated. They were renowned for vastly depleting supplies, and could eat practically anything.
- Sand snakes
- Tunnel snakes
- Water snakes
Birds and Bird Like Creatures
- Wherries are large avian creatures distantly related to the tunnel snake. Their middle set of limbs are large leathery wings. Unlike Terran birds the Wherry is covered in a soft fur like down. Wherries are used as food stock, and their fatty flesh will often be an indication of where it fed, picking up a fishy taste when it feeds by the sea, and a nutty taste when it has feed on grains from the plains. They were named for their resemblance to Wherries, a form of flat-bottomed barge used on Earth, by the EEC survey team. It is unclear in the books if there are different species of wherries.
Insects and Insect Like Creatures
- VTOL - A harmless flying insect, they were named by the survey party for their ability to perform vertical take off and landings.
- Grubs - small, gray, furry, and legless creatures engineered by Ted Tubberman from a native species to eat burrowing Thread before it could cause any damage; they were further modified by his son, Purman, into "vine grubs" that would help plants grow as well as protect them from Thread
- Trundlebugs - A useful insect that eats parasites, turns the soil and acts as a pollinator. They have the most elaborate color camouflage of all the insects found on Pern and come in many colors. Their young cling to the mother and form a line of trundlebugs until something seperates them. Trundlebugs always travel in a straight line until something forces them to turn or moves them to face another direction. If they are annoyed in any way, their defense is to release a HORRIBLE smell. Tai said they have scratchy feet according to her dragon, Golanth didn't like them so Zaranth, show him how to move them without crushing them, like the first time, Tai also said they can swim.
- Fy-bys - small gnat-like insect
- Rockmites - Small water-dwelling beetle-like insects
- Rollers - a type of wood louse
- Scatid - a six-limbed burrowing insect smaller than a human thumbnail, with the two front limbs adapted for digging; there are at least two species: a northern one with thinner diggers and furry back legs, and a southern one with wider diggers for pushing away sand
- Wrigglers - a small worm-like creature
- Sandworms - an armored Thread-eating worm that lives near Igen Hold
Fish and Sea Creatures
Fish are the most common and diverse form of life on Pern. There are many different species, with varieties of each. It was theorised by the colonists that the lack of diversity of land creatures, and the massive variety of sea life, were both a direct effect of Thread. A number of fishholds were established to take advantage of this.
- Bordo Northern version of the Packtail, 
- Packtail - A deep-sea fish. It is covered in slime that can cause infections in humans if it gets into an open wound.
- Redfin 
- Rainbow 
- Spiderclaw - A plump shellfish, that looks like a crab with many legs. They lay their eggs on sandy beaches in the Spring. They can be smoked, salted or dried and they retain their flavor in long cooking dishes.
The colonists brought cryostored sperm and eggs which they implanted in surrogate horses and cows that had been transported in cold sleep.
- A catch all term used to discribe bovine, porcine, and sheep and goat stock, Herdbeasts are used for their meat, milk and hides much like they are on Earth and the other colonies.
- Descended from horses, the Pernese Runnerbeast is as diverse in its breeding as its forefathers, ranging from fast sprinters to sturdy draft beasts used to haul trader wagons. They were used by the Runner Craft to carry messages from holders who did not have easy access to Drumheights or Weyrs.
- Another catch all term for any beast that us used to pull a cart or other form of serious labor. Draybeast covers Oxen, mules, and possibly llamas.
- 25 Bottle-nosed Dolphins (also known as Shipfish), who had been given mentasynth enhancements, volunteered to assist in the mapping of Pern's large oceans. They were capable of speaking in English to the Pernese. During the First and Ninth Passes they were accompanied by human companions, or Dolphineers.
- Cheetahs (later known as Felines) were brought by the colonists, but weren't used until Ted Tubberman enhanced them with mentasynth to serve as guard animals. The cheetahs killed Tubberman and escaped. By the Ninth Pass, they had spread across the Southern Continent . Despite being descended from cheetahs, there was considerable variety in their coat patterns. They were the largest predators in the Southern Continent's ecosystem, and they were a frequent hazard to humans, even attacking a dragon on at least one occasion.
- Lions (felines) a pride had there den home, was the bad spot that M'ling and P'tero chose while they were south.
- On the Far Western Continent during the Second Interval, there was a population of Felines known as Mrreows. These Felines' preferred prey was Tunnel Snakes, and they would push aside easy prey to get to them. Other than that, they were similar to Southern Continent Felines. Shortly after the Ninth Pass, there was no sign of them. In fact, Thread fall had killed all life on the continent except Tunnel Snakes.
Fish and Sea Creatures
- Minnow 
- Mentioned once, Fur beasts are small animals trapped for food and their skins. it is unclear of they are native to Pern or where a marginally successful introduced species.
- Whersports, a species related to dragons native to the Southern Continent, are larger than a fire-lizard and smaller than a watch-wher. Humans can eat them.
- Deep Ones are a large, aquatic species that live near Tillek. They go to depths beyond any trawling ships' nets, but are capable of coming to the surface. They create spouts of water, similar to the ones created by dolphins when they exhale. According to harpers, they came on the "Great Crossing" (which may refer to either the First or Second Crossing), and they help people by herding fish. Lorana described them as "almost" telepathic, and similar to dolphins, but "much bigger" and "different." They are presumably descended from whales.