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.

Krakowpedes
Krakowpedes are a group of superficially arthropod-like fauna characterized by having multiple pairs of legs and a usually worm-like shape. Most krakowpedes are ancestrally blind, typically tasting or feeling the environment, but a few clades later developed eyes. Interestingly, they are an outgroup of the purple flora, as they all descended from a species of purple algae that incorportated heterotrophic endosymbionts, allowing them to forgo photosynthesis in favor of deriving energy from other organisms. Krakowpedes are also referred to as "anipedes" or "segmentocaudans".

Trappers
Splitting from the krakowpede tree before the anipedes and centifins, the trappers are a relatively obscure group of exclusively marine worm-like fauna with multipartite jaws. Excepting the aberrant early-offshoot jetters, most taxa are sessile or slow-moving predators, either buried in the substrate or simply hidden in plain sight, snapping at prey when they least suspect it. As for the jetters, they take the niche of far more active pursuit predators, complete with jet propulsion organs and two sets of jaws: the main ancestral jaws, and a unique jaw-tipped trunk.

Centifins
Centifins are an ancient group of krakowpedes. While the earliest species could be recognized by their multiple limbs, long and slender forms, as well as the precursor exoskeleton. Many modern centifins have further evolved this exoskeleton and now possess three ocular organs as well. These descendants take on a variety of roles such small scavengers as well as larger mesopredators, and possess clear body segmentation - such as a distinct head region - and reduced number of limbs. Others maintain are more serpentine body plan much like their distant ancestors, though possess complex jaws for snaring prey and lack limbs for locomotion entirely. For the most part, this group is primarily aquatic, with some exceptions managing to adapt to dry land via earlier colonization in moist, warm regions such as rainforests.

True Anipedes
While all krakowpedes can informally be called "anipedes", only one class can be called true anipedes. These superficially crustacean-like fauna possess beak-like jaws and multiple pairs of specialized limbs - from walking legs, to antennae, to pincers, to paddling pleopods. In some clades however, the walking legs are reduced. Most true anipedes are small in size, and take up niches as plankton or in the benthos, however a select few taxa have achieved larger sizes, and have even left the waters behind.

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.

Sea Plents
Sea plents are a highly diverse group of plents, coming in a myriad of forms, lifestyles, and sizes. Despite the name, several different lineages have independently attempted to colonize the land, with varying degrees of success. From the microscopic to the titanic, sea plents have proven to be incredibly successful and broad group, forming nearly all ladders in the aquatic food chains they make up at one time or another, though nowadays the vast majority of sea plents are on the smaller side of the scale. Planktonic blooms of both miniswarmers and microswarmers in particular provide food for a large variety of marine life, and help to support populations of gilltails, snarks, and other aquatic predators. While primarily free-swimming, some have evolved both sessile and benthic lifestyles in order to exploit new niches and avoid competition with their many evolutionary rivals.

Shockers
Shockers are the most basal of the modern sea plents, possessing relatively fish-like bodies and electrifying jaws.

Swarmers
Swarmers are the most numerous and diverse of the sea plents. Aside from the shockers, all modern sea plents descend from this group. Some species are somewhat fish-like, while others are microscopic and borderline sessile, fulfilling the role of phytoplankton. They also have several distinct subgroups diverging from these norms.

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 terrestrial 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. Some of them closely resemble basal plents, while others are more plant-like with traditional leaves, wood, bark, and even roots. A handful of species are cursorial.

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 (found mostly in Wallace, Koseman, and Drake), ketters, and nobits (found in Wallace and Barlowe).

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 found on most landmasses and are also the only living group to retain flight. Related to them are the emulsechoes (found in Barlowe), 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 and live in Wallace or Koseman. Despite their appearance, bearhogs are not closely related to the no-plents, having developed a mammalian profile independently. In fact, the closest living relatives to the bearhogs are the gulpers.

Gulpers
Gulpers are among the more derived plents, lacking leaves or front limbs and having spider-like fangs and long prehensile tongues. This bizarre appearance means that at a casual glance, one might not even recognize them as plents. Most modern species have armored heads and can zap predators or prey with an electric tongue. They can be found on all landmasses, but most of their diversity is in Wallace and Drake.

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, both of which can be found all over Sagan 4's oceans.

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

Murkworms
The secondarily aquatic murkworms were once very diverse, but are now restricted to just a few filter-feeding species. They are the closest living relatives to the Saucebacks and are found in Wallace, Koseman, and Fermi.

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:
 * Waxfaces, which are found in Barlowe and along coastlines
 * Larvabacks, which are aquatic and found in most waterways
 * Loafshells, which are found on Drake
 * Shrewbacks, which are found on most landmasses
 * Biats, which are found mostly in Wallace and Koseman

Scuttlecrabs
These surprisingly close cousins of saucebacks and murkworms resemble ordinarily arthropods, but often have leathery skin covering their exoskeleton. In modern times, scuttlecrabs consist of the Kruggs (which are global), the Korrybugs they descend from (which are found along polar and subpolar coastlines), and the Crystank Walkers (found in Drake).

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. Among them are the fairyshells of Barlowe, which have four legs and long sensory limbs, and the gossalizards, which can produce silk, have eight legs (or 6 legs and 2 arms), and come in both cold-blooded reptile-bug varieties in Barlowe and fuzzy lukewarm-blooded varieties in Drake.

Wingworms
Wingworms are Sagan 4's closest analog to flying insects and are very diverse, being found on every landmass. 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.

Filtersquids
The closest relatives to modern marephasmatises, filtersquids generally resemble cephalopods in appearance.

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
Nearly all 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. They constitute a significant portion of Sagan 4's current megafauna.

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.

Charybs
Charybs are distinguished from other fee due to their multicellular nature. All current extant species are descended from charybdis, and on average tend to possess a lifecycle involving multiple distinct stages as well as sexual dimorphism. At least one lineage has developed a symbiotic relationship with photosynthetic organisms which grow within specialized nodules on branch-like extensions off their main body.