Introduction to Extant Fauna

Sagan 4 is home to many groups of fauna both living and extinct, and for a newcomer just starting to explore its diverse array of biota, knowing where to start can be difficult. This guide serves to introduce each major group of living fauna on Sagan 4.

For extinct clades and evolutionary grades, see the Introduction to Extinct Fauna.

Plents
Plents have historically made up a significant portion of Sagan 4's biota. A sort of "planimal", many species are both motile and capable of photosynthesis using a pair of large, mobile leaves. Many species have repurposed their leaves for swimming, flight, or thermoregulation, with or without retaining photosynthesis, while some have lost them completely.

Zappers
Zappers are relatively fish-like sea plents with electrifying jaws.

Swarmers
Swarmers are the most numerous and diverse of the sea plents. Some species are somewhat fish-like, while others are microscopic and borderline sessile, fulfilling the role of phytoplankton.

Skuniks
Unlike most sea plents, modern skuniks are terrestrial and walk on 6 legs usually supported by an exoskeleton. They are also among the few major groups of plents to have a through gut, rather than a blind gut.

Plyents


Plyents are sea plents which behave like plants...almost. Unlike the extinct tree plents, many plyents retain the ability to move around and truly toe the line between plant and animal.

Plyents are technically a kind of swarmer which sits on its many tails with its mouth facing upwards.

Walking Plents
Walking plents are, surprisingly, a sister group to the sea plents rather than a clade within them. Walking upon four legs supported by flexible "wooden bones", walking plents have historically constituted much of Sagan 4's megafauna.

No-Plents
No-plents are the earliest-diverging major group of walking plents characterized by a superficially mammal-like profile and, in some species, an extra pair of eyes. Most modern species are fairly small and herbivorous. Living types of no-plent include nodents, ketters, and nobits.

Flying Plents
Flying plents are among the few modern walking plents to mostly retain large, functional leaves, not because they are dependent on photosynthesis, but because they use them to fly. Incredibly diverse, flying plents make up a significant portion of all plents living or extinct and feed on a myriad of different food sources.

Most modern species of flying plent are specifically phlyers, which are also the only living group to retain flight. Related to them are the emulsechoes, the sprinters, and the bandersnatches, which each lost flight independently.

Bearhogs
Relatively basal in anatomy as far as modern plents go, bearhogs also retain their leaves. Most living species are herbivorous. They developed a mammalian profile independently of the distantly related no-plents.

Gulpers
Gulpers are among the more derived plents, lacking leaves or front limbs and having spider-like fangs and long prehensile tongues. Most modern species have armored heads and can zap predators or prey with an electric tongue.

Worms
Contrary to their name, worms are some of the most complex fauna on Sagan 4. An ancient symbiosis of animal- and plant-like cells, worms are known for their two distinct cell lines, the fleshy "red cells" which make up most of their flesh and the rigid "green cells" which have cell walls and originally formed a living exoskeleton.

Beakworms
Beakworms make up most of Sagan 4's "fish". A unique branch of their own, they have the most reduced green tissue of all the worm groups. Some prominent kinds of beakworm are gilltails and gillfins.

Bubblehorns
Bubblehorns somewhat resemble many-legged snails with prominent sensory "horns".

Murkworms
The secondarily aquatic murkworms were once very diverse, but are now restricted to just a few filter-feeding species.

Saucebacks
Saucebacks look out of place among other worms, with their feathered bodies and single pair of legs making them somewhat resemble dinosaurs, if one ignores their mammalish ears and insect-like jaws. Unlike their cousins, saucebacks have a primarily internal skeleton which allows them to reach great sizes. The earliest saucebacks, and many modern species to this day, lack eyes and instead navigate their world using echolocation.

Saucebacks are very diverse and are found on every landmass. Some major types of saucebacks include the waxfaces, the aquatic larvabacks, the loafshells, the tiny shrewbacks, and the bird-like biats.

Scuttlecrabs
These surprisingly close cousins of saucebacks and murkworms resemble ordinarily arthropods, but often have leathery skin covering their exoskeleton.

Lizardworms
Lizardworms are a subgroup of scuttlecrabs which, as their name suggests, resemble reptiles with exoskeletons. They also have an endoskeleton and can get fairly large.

Wingworms
Wingworms are Sagan 4's closest analog to flying insects and are very diverse. They evolved from 12-winged, many-legged ancestors with many eyes on their backs, but the status and number of all of these vastly varies across the many living groups.

Marephasmatises
The radially symmetric jelly-like carpozoans are, in the modern day, represented only by the stinging rainbow marephasmatises. These are the most basal and ancient of all living carpozoans.

Spondylozoans
Spondylozoans are the vertebrate-like side of carpozoa which bear an internal skeleton and constitute some of Sagan 4's megafauna. Though similar to Terran vertebrates, they commonly have 6 eyes, and terrestrial forms have unusual shoulder-like hip anatomy.

Snarks
Resembling fish with nasal gills, snarks form a considerable portion of Sagan 4's oceanic megafauna. Most modern snarks are scylarians, which have just one pair of flippers.

Caudopods
Caudopods are a terrestrial branch of spondylozoa which are named for their ancestral locomotion which involved walking on the tail. Originally the reptile-like grade to snappers' amphibia, today they are represented mostly by therapsid-like forms.

Dwellers
Modern dwellers consist of the pentapedal glasseaters and the tripodal grubnubs, respectively bearing goat- and bat-like faces and prominent ear-crests.

Shrews
Shrews are very mammal-like caudopods which, unlike the dwellers, no longer walk on their tails. They can be distinguished from most other terrestrial spondylozoans by their mammal-like faces, and from the (relatively) closely related dwellers by their retention of all 6 eyes. They come in two broad varieties, the highly mammalian furred shrews and the more reptile-like blood shrews (bubbleskins and soriparasites).

Snappers
Snappers form most of the reptile- and amphibian-like spondylozoans.

Skysnappers
Skysnappers are warm-blooded, bird-like snappers with hollow bones and membranous wings.

Turtsnappers
Turtsnappers, as their name suggests, are descended from turtle-like creatures. However, many have reduced armor and instead fill the role of various kinds of reptile or amphibian. Despite their reptilian appearance, the majority of turtsnappers must lay their eggs in water.

Earbacks
Earbacks are an ancient, rare line of snappers with ears on their backs. Modern representatives are descended from blind cave-dwelling species.

Limblesses
Limblesses represent a distinct branch from other terrestrial spondylozoans, closer to snappers than to caudopods, which lost all of their limbs.

Iron Fauna


Iron fauna are magnetic, arthropod-like creatures which metabolize dietary iron as part of their respiration.

Whorls
The whorls are primitive, radially symmetric cousins of ukfauna with long tails and other trailing structures.

Fee
Fee (singular: foi) are unique among Sagan 4's fauna in that they consist only of a single, highly complex cell.