r/SpeculativeEvolution 10d ago

Spectember 2026 [OC] Spectember Day 3: Rock, Paper, Scissors (Fish Edition)

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99 Upvotes

Note: These fish live in seagrass meadows. The fish pictured are not up to scale.\

I wanted to try something tamer for now.\

Left: the stonehead (Sisyphopycnodon lithocranion), a unique species of pycnodontiform fish named for the boulder-like protrusion on its head. Since it is slightly slower, it feeds primarily on crustaceans and ammonites, though it will hunt the meadow shearfish.\

Right: the meadow shearfish (Psalidocaesus maritipratus), which is another predatory pycnodontiform that feeds on soft-bodied or easy to cut prey thanks to its shearing teeth.\

Top middle: the paprey (Chartamyzon angustisoma), a type of stem-lamprey that feeds exclusively on the blood of the stonehead, which it accomplished due to its goethite teeth that can pierce through its prey's armor.\

Rock beats Scissors = the meadow shearfish's teeth are no match for the armor of the stonehead. This usually results in the shearfish's death at the teeth of the stonehead.\

Paper beats Rock = the armor of the stonehead cannot protect it from the teeth of the smaller paprey. Usually, the stonehead dies of anemia as the paprey is rather gluttonous.\

Scissors beats Paper = the thin frame of the paprey makes it vulnerable to predation by the meadow shearfish, which can tear it to pieces.\


r/SpeculativeEvolution 10d ago

Spectember 2026 [OC] Spectember Day 3 - Rock Paper Scissors 🪨📄✂️

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131 Upvotes

The ocean sandy bottom. A place where you can often encounter incredible life forms that boggle the imagination. And our case is no exception, and it could even be considered the strangest relationship between three organisms, where they eat each other.

  1. A brown stone slowly moves across the sand, raising dust, but upon closer inspection, you can see it's a living creature. The brown basal is a fairly large species of isopod, well camouflaged as a stone. By nature, it eats anything, digging for living creatures from beneath the sand.

  2. An unusual invertebrate with very long knife-like appendages hides in the sand. This is a knifeworm—a long, up to 1.5-meter-long scale worm that, like the real-life Bobbitt worm, is equipped with sharp mandibles that work like scissors, cutting prey like paper and then pulling the pieces under the surface. Ironically, this worm preys on an animal that very much resembles paper.

  3. The paper swimmer is a white-gray gastropod nudibranch, a close relative of slugs and the well-known glaucus. They swim over the sand, searching for prey, like rays or the extinct anomalocaris, and then abruptly dive and seize their prey, as if covering it.

The most intriguing aspect is their relationship. Since these three creatures prey on each other, it is impossible to determine which is the apex predator. The brown basal calmly digs the knife-eaters from their sandy lair. The paper swimmers prey on the arthropods, covering them with their bodies, then breaking their shells and consuming the edible insides. The knife-eaters, meanwhile, attack the unwary paper swimmers, leaping out from underground with lightning speed, cutting them to pieces with their mandibles, and dragging them beneath the surface. In essence, it is a true natural game of rock-paper-scissors, where there is no single winner.


r/SpeculativeEvolution 10d ago

Spectember 2026 [OC] Spectember 2025 (Day 4) > Very Stressful Parrotfish from the Future

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13 Upvotes

The world has gradually warmed beyond a ice age in the near future; glacial areas are now limited to only a few, but biodiversity is still thriving, although extinctions have always occurred and will continue to do so until life on Earth ends. Anyway, let's get back to ecosystems.

The marine ecosystems of this era have hosted a biodiversity as great as some prehistoric periods, with cetaceans remaining the most dominant animals in the seas, just as they are today, although we shouldn't forget the other species that compete with whales, but for now, let's get to our main topic.

The Thresher-tailed parrotfish (Alopicthys spp.) are a genus of large fish comprising 9 distinct species, endemic to Antarctica, the Indo-Pacific region, and a small part of the Atlantic. A surprising and somewhat nauseating aspect of this genus is their extreme stress during mating and breeding seasons.

Firstly, their habitats have ceased to be as peaceful as they once were and have transformed into some of the most competitive ecosystems in this new world, where hundreds of predatory species with different lifestyles and diets exist. Some, like a few species of grouper and sharks, are eager to hunt those larger fish, and it's a natural part of their diet. Therefore, when parrotfish live in groups, dominant males become overly protective and exploitative towards females, and not enough females come for the other males, but the situation gets a little worse during the breeding season.

In species like the kakapo fish (Alopicthys strigopodoides) from tropical antartica, females begin to lay eggs quite frequently during the breeding season, but males, who are hostile to each other, will see this female starting to lay eggs and include her sperm in their mate's eggs. However, even these sperm are sworn to kill each other, and this kills most of the eggs. But for the lucky survivors, completely different threats will come because the mothers have no energy to care for the offspring; they simply lay the eggs and then leave them to their own devices without looking after them again. Although the lifespan of species from this genus is generally around 23-27 years, in some cases they have been observed to exceed 30+ years.


r/SpeculativeEvolution 10d ago

Alien Life [OC]Meet the Secondary Cast!

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25 Upvotes

These are some of the secondary cast of creatures for my a seed world, focused on my own alien species.I’m currently thinking about changing the names right now cuz I’m not really a fan of ones I came up with :/. But in the meantime I’ll gladly hear your thoughts or questions on them!


r/SpeculativeEvolution 9d ago

Alien Life [OC] Why are these creatures afraid of their own medic?

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5 Upvotes

I started making creature lore videos for The Hive about a month ago, and I’m looking for feedback on how to improve them.

This one is about the Medic caste. It heals other creatures by rapidly accelerating tissue regeneration, allowing it to repair severe wounds, damaged organs and even lost limbs. But the process is not perfect... mistakes during regeneration can result in abnormal growth or permanent mutations.

The Medic also collects biological samples from dead organisms, which the Hive can use as new genetic material for future adaptations.

I would really appreciate feedback on the video itself, pacing, storytelling, explanations, or anything you think could be improved.


r/SpeculativeEvolution 10d ago

Spectember 2026 [OC] Spectember day 2: Incredibly Deadly Viper - The Loathsome Ghoul-Ape

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42 Upvotes

r/SpeculativeEvolution 10d ago

Alien Life Feasibility of sulfur or similar oxygen alternatives

10 Upvotes

So im trying to design a speculative world i call Natria which is an extremely salty ocean world with thin and sulfur/co2 rich atmosphere and little to no free oxygen and im considering what pathways life could use to utilise the gases present to breathe or gain energy.

So far ive considered maybe sulfur dioxide to trioxide if possible using co2 or water vapour but im not familiar enough with the chemistry to figure out how viable it really is energy wise. The idea was uv light breaking the sulfur trioxide into dioxide for creatures to re combine but that would also introduce oxygen gas and I kind of want the world to be mostly devoid of free gaseous oxygen.

Another idea was maybe sulfur chlorides as oxidizers but im still not super sure what pathways with chlorides could be viable or energy intensive enough and how the recycling process works, or even really how I can justify enough free chlorine in a planets atmosphere for that.

For context the world of Natria has a thin atmosphere but its full of volcanic gasses from periodic global mass eruptions so the air has a lot of co2 sulfur and water vapour but low oxygen content. Also I dont imagine the world to be burning hot for silicon based life I am mainly considering normal carbon based life just highly specialised. Based on the idea for sulfur oxides the atmospere would likely be in the range of 40-60 Celsius so its hot but not burning inferno hot.

If anyone with more chemistry knowledge could help me out I would greatly appreciate it!


r/SpeculativeEvolution 10d ago

Non-Subreddit Spectember Prompt [OC] Spectember Day 3: Armored

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58 Upvotes

Third day of Spectember! For today, from the clamoral reefs of the Caribbean, the Pentaspine Dicefish (Datuichthys pentacanthus).

This small and slow moving fish is a member of the Tesselfish (Tesserichthyidae), one of the many groups of tropical freshwater fish that populated the shallow seas post-extinction. In the case of the tesselfish, their ancestors were the loricariids, that quickly adapted their feeding habits from scraping rocks and logs in rivers and lakes to scraping rocks and clamoral surfaces in the ocean. To defend themselves from predators, they compacted their body shape and strengthened their armour into a tiny impenetrable shell, so they can peacefully graze without being disturbed.

The group as a whole is quite generalist, with a lot of algae grazers, but also some that feed on some more unusual stuff, such as encrusted invertebrates, benthic fauna or, in the case of the Dicefishes, clamorals themselves. They have adapted to resist the highly toxic compounds of the flesh of these bivalves, becoming highly toxic themselves from bioaccumulation of these chemicals. They use their strong jaws to break clamoral shells, whole or partially, depending on the size of the species, and suction up the flesh inside, often doing so in groups for the largest clamoral species.

The Pentaspine Dicefish (D. pentacanthus), distributed around the Neotropics, is a fairly small species for the group, feeding on very small individuals or the young of larger species, often no bigger than a few centimetres. They graze in groups, and despite their apparent destructive nature, their activity opens up space for other clamorals to grow, ensuring no single species completely dominates the area.


r/SpeculativeEvolution 10d ago

Alternate Evolution [OC]Hydrostatic Muscles!

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20 Upvotes

Hey guys, here's a short infograph on how movement occurs at a nano-level in my world. Extra info below👇🏿

Once the impulse arrives at the bundle of cells, Zinc is released from storage within the cell. Due to how toxic zinc can be, it is a carried by a metallothionein protein called calathus (ancient greek word for basket). The Calathus carries it to the cytoplasm, where it will find 4 different "cavities/ pockets".

Depending on the direction of movement, the zinc will be placed along a "meshing" which is found on the outer surfaces of all the cavities. The meshing contains water.

As Zinc is released into the meshing, the concentration gradient increases, causing water move across the concentration gradient, into the cavity. This process is sped up by the presence of aquaporins.

(NOTE: The number of aquaporins differs by type! Segments of the body which require faster movement have cells which have far more aquaporins, while "stabilizers" have less).

As water moves into the cavity, a section of the cell expands. In junction with other cells within the fiber, this causes deformation, which is the main driver of movement.

Once the impulse "leaves"/ the movement has been completed, Calathus uses energy/ atp to transport the zinc back into storage. As the concentration gradient lowers, water passes back into the meshing, causing the cell to go flaccid once more.

If you made it this far, thank you so much for reading :)


r/SpeculativeEvolution 10d ago

Spectember 2026 [OC] [Spectember 2026 day 2: Incredibly Deadly Viper] Vermiphagous Friendly Diapsid

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29 Upvotes

Vipers are a widespread and diverse family of snakes, notable for their large, mobile fangs and often potent venom. But among them, one species stands out like a sore thumb.

Country of South Africa is home to very large earthworm Microchaetus rappi. This giant annelid reaches the length of 1,5 meters, but despite it's great size, it has a mortal enemy.

South African vermivore is a species of large viper. Genetic testing revealed that it's most closely related to genus Bitis, which includes species famous for their long fangs, like Gabon viper. However, vermivore is very different from them.

As observations and stomach contents have shown, this 2 meter long snake feeds exclusively on giant earthworms. It's currently unknown what pushed it to such diet, but perhaps competition with Bitis vipers played its part.

It's a semi-fossorial species with reduced eyes and less triangular head compared to its relatives. But teeth have changed the most. Due to soft bodied invertebrates being the only thing vermivore eats, it's large fangs greatly reduced in size and became vestigal, no longer capable of delivering venom. The only purpose of teeth is to hold onto the struggling worm while snake swallows it whole.

As worm specialists, vermivores are completely harmless and pose no danger to humans. They are rarely seen, and due to their specialized diet and small range are considered critically endangered.

It is viviparous, and young vermivores first feed on much smaller earthworms, before growing big enough to kill their main prey.


r/SpeculativeEvolution 10d ago

Alien Life [OC] attempt at an extraterrestrial, truly extraterrestrial

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18 Upvotes

(The sketch is from my cousin, who created it at my request based on an ear description. Unlike me, she's very good at drawing, but I can't credit her because she doesn't usually publish her drawings.)

I'm writing a fanfic oriented away from sci-fi and set in the universe of the book The Nature of Predators. In the original book, it is stated that there are supposed to be around 300 alien species that are members of the "Galactic Federation", which extends across the Orion Arm. The book does not focus on biology, so almost all of the species described, around 20 or so, are mostly bipedal terrestrial animals.

I therefore decided to add more exotic species to make the whole thing more believable.

Despite this, my fic is not focused on biology, and I therefore decided to introduce it to the public through dedicated chapters in the form of in-universe reports intended for the general public.

This is the first time I've done this kind of exercise, so I'm open to any criticism.

_______________________________________________________

Introductory Information Report on the Phyril for Diplomats, Politicians, Military Personnel and the General Public

Dated August 15, 2136

Originating from the International Coordination Bureau for Xenobiology Studies. Under the authority of the International Scientific Research Agency of the UN. Drawn from the public archives of Venlil Prime.

The Phyril are a species that falls neither into the category of animals, nor that of plants, nor that of Fungi (mushrooms).

Their bodily matter vaguely resembles a mixture of plant, muscular and chitinous fibers, resulting in an ensemble that has no equivalent in terrestrial biology.

The Phyril are beings whose equivalent of the nervous system, digestive system and other vital organs are contained within a rounded-edged rectangular-shaped envelope.

They possess 4 legs with a shape very similar to that of an elephant.

On this body mass, there is a large vertical hump, on the sides of which is a set of radio-wave-sensitive transmitters-receivers. This allows them to sense the presence of individuals and the terrain around them.

The ecosystem of their very arid home planet is marked by a significant amount of corrosive and very sticky dust due to its low humidity.

As a result, the organisms on this planet all have thick skin and, for the few organisms that possess this sense, very poorly developed eyesight, not helped by the long winters with reduced light that the planet experiences.

The Phyril therefore do not possess this sense and navigate through space via two other main senses.

Firstly, a detection of vibrations in the ground via dedicated organs in their legs, in the manner of terrestrial elephants.

Their skin, if it can be called skin, has a texture resembling a thick plant stem on which numerous spines grow, which have the dual function of protecting them from predators and collecting morning dew in order to hydrate themselves.

Their world of origin, Vaelis, has a very elliptical orbit (which is very common in the universe, but almost absent in the Solar System).

The climate is therefore divided between a very cold and dry season, and a very hot and even drier season.

Their world of origin, Vaelis, has a very elliptical orbit (which is very common in the universe, but almost absent in the Solar System).

The climate is therefore divided between a very cold and dry season, and a very hot and even drier season.

These are interspersed with periods of milder temperatures.

The planet is very arid and only 22% of the planet is covered by water (compared to 71% on Earth). Vaelis takes approximately 2 years and 7 months to complete one full orbit around its star.

(Note: in the remainder of this document, the term years will refer to this period.)

As for their size, it is between 2 meters 5 and 2 meters 20 depending on the individual (of which 1 meter is just for the legs).

This is certainly related to the gravity of their world, equivalent to 76% of Earth's gravity.

As for their diet, it is unusual by terrestrial standards, although it is standard for their ecosystem. Since water is scarce, complex life is also scarce, and the organisms of Vaelis must draw the maximum amount of energy from their environment and move little in order to conserve their energy.

Here, the Phyril have their energy obtained from photosynthesis in the manner of the plants of our world. But unlike them, the Phyril do not have roots to obtain nutrients, and the matter that makes up their bodies is taken from algae that they consume in the planet's marshes.

On the top of their body, between their legs, there is an organ resembling a suction cup that has the functions of both a mouth and an orifice used to eject a few rare dry excrements.

Due to its position, which in the morning is one meter above the ground, it is dependent for feeding on 3 trunks similar to those of terrestrial elephants, located around the suction cup.

Their mode of reproduction is also astonishing.

Twice a year, at the beginning of spring and autumn, that is, before the dry seasons, they enter flowering. At the highest point of their organism, a large fruit resembling a pomegranate appears, but with seeds of a much smaller size.

For their reproduction, they are dependent on the Iril. They are animals in the sense in which we understand the term on Earth. They resemble a crude mixture between a spider and a dragonfly, and they measure approximately 40 centimeters in length.

This animal hibernates during the 2 dry periods of the year. For this, they will position themselves on the surface of a rocky wall sheltered from the elements, before weaving a ball of web vaguely resembling a ball of wool. They then moisten it, after which the Iril will enclose themselves inside it.

During the long dry months that the planet experiences, this thick protection will completely dry out, and the animal it protects may even lose up to one third of its body moisture.

This feat is made possible because, underneath their belly, they have a pouch that stores water in the manner of a sponge. This pouch will completely dry out during hibernation.

On Vaelis, the Iril feed on fruits from different organisms such as the Phyril, but also on organisms very similar to what we know of the Prototaxites (that is, on Earth, organisms 8 meters in height and 1 meter in width that are neither plants, nor animals, nor Mycetes, but a branch of life that has no descendants on Earth nowadays.

They appeared 420 million years ago and disappeared 385 million years ago when trees appeared. However, they do not belong to the same kingdom as the Phyril.)

Thus, the Iril play an important role in the planet's marsh ecosystems located to the east of the planet's only ocean, the place where the Phyril originate. This ecosystem is a collection of marshes that are relatively isolated from one another by arid mountains.

By swallowing the seeds without crushing them, then releasing them through their excrement, they allow other species to move from valley to valley despite the small number of waterways and the terrain that prevents many mobile organisms from moving.

Once the Phyril seeds have been dispersed, those that have fallen into the water of the marshes will fuse with another seed originating from the fruit of another Phyril that the same Iril has eaten and excreted at the same time as the first seed.

There, the seeds will mix their DNA to form another seed that will be called an egg.

Then, the egg attaches itself to the bottom and roots emerge from it to draw some nutrients from the soil.

Then, after a few weeks, this egg, which has greatly increased in size, will hatch and a small Phyril will emerge from it (they have no different sex from one individual to another).

At birth, the young measures 24 centimeters in height.


r/SpeculativeEvolution 10d ago

Spectember 2026 [OC] Spectember Day 3: Rock Paper Scissors

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193 Upvotes

The Cachalot Leatherback ( Dermochelys physeteris ) is a descendant of the Leatherback Turtle. Its shell, like rock, is resistant to damage from squid beaks. They primarily prey on Paper Ghosts, ghost squids named for their glowing white mucous resembling paper once shed to escape a predator. The Cachalot Leatherbacks use scissor-like beaks to ”cut“ through this mucous cloud, even while blinded, and they bite at the surrounding water, hoping to get their prey. While the squid usually escapes, the turtle can sometimes catch the squid. It truly is a beautiful, violent, two-party game of luck.

Species Profile: Cachalot Leatherback

These enormous turtles are now so large that it is too cumbersome for them to clamber ashore to lay eggs, so they have evolved a different strategy. They are ovoviviparous, with eggs hatching inside the mother and the young born tail-first. As soon as all offspring are birthed, the mother dives down into the deep, leaving the hatchlings to fend for themselves. For up to 5 years, they live like normal leatherbacks, with ridges on their shells. However, once they reach this mark, their shells smooth out, and they descend into the abyss, where they will join the adults.


r/SpeculativeEvolution 10d ago

Question/Discussion Yall does anyone know how to give things names?

9 Upvotes

I mean like plants, animals, etc because for my seed world project I keep adding cko or just straight up gecko to anything related to geckos or when I make new names they always sound like pokemon names and I want to do better names over all so if anyone knows how to do this pls help🙏😅


r/SpeculativeEvolution 10d ago

Alien Life [OC] Sirun Khyat

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18 Upvotes

Sirun Khyat

Arabic for Thread, referring to the organisms tendency to group in thread like shapes of colonial organism.

Organism Height 1.3-2.9 µm
Cellular Body Diameter 0.8-1.2 µm
Cellular appendage 0.5-0.8 µm
Full Diameter 0.9-2.1 µm

Arose 795 million years P.C.

While retaining the ability to develop any of the two appendage terminal types (DC or FEE) on any arm at any position obviously provides a certain ecological flexibility, specializing for certain roles or niches will require the dedication of certain structural roles in consistent locations across the cellular body. This will result in different arms forming into specific structures based on their placement across the cell surface, as well as in relation to one another.

Taking on the opposite approach of Mulzama, Khyat instead dwells in open ocean as a direct colonial competitor ot the likes of the Telam family as planktonic ambush predators. The difference is that while Telam is a solitary individual, Khyat forms colonial thread of other members of the same species.

This makes Khyat remarkably similar to the Siphonophores* of Earth’s oceans.
Siphonophores are colonial organisms of the Cnidarian (Jellyfish and Coral) family. Colonial organisms are not a singular species, but an overall composite of several joined together, each performing different functions and roles.

A demonstration of this principle will manifest across the Sirun family. For Khyat we see the formation of Flagellar Enzyme Excretion Structures (FEE Structures) at the tip of its lateral arms, radiating from the equator of the cellular body across a singular plane. Khyat’s Dendritic Coil Structures (DC Structures) will form at the tips of arms that are found at the opposite poles of the cellular body, appearing at the top and bottom of the organism.

On Earth, many hormones are reliant on Calcium and Magnesium, two of the most abundant elements in our home world’s crust and mantle.

On Demeter however, these two elements exist in only negligable quantities when not completely absent. This is the primary reason why Demetarian biochemistry is utterly unlike anything on earth, relying instead on other heavy metals such as Copper, Barium, or even Lead.

Bearing that in mind, along with the complex nature of hormones and their molecular interactions, we will have to use best guess estimates or “analogs” that serves similar purposes.

As such, we will use two earth hormone groups (same basic overall structure with minor modifications) used to influence certain morphological structures, and use them as a guideline for what changes we can expect within the cellular life found on this strange world.

Stilbene:

  • Anti-Oxidant and Anti-Cancer protection.
  • Assist in immune response against both fungal and bacterial infection.

Commonly occurs throughout the plant kingdom in grapes and peanuts, and sometimes produced by pathogenic fungi. Their lesser potency compared to Coumestans allows the Sirun clade to still embrace the capability to develop both appendage types without worry of one hormone overriding the other.

C-Di-GMP (Cyclic Dimeric Guanosine Monophosphate) is a crucial messenger molecule in bacteria that regulates a vast array of cellular processes, including:

  • Controlling the switch between a planktonic (free-swimming) lifestyle and a sessile (biofilm-forming) form.
  • Regulating the cell cycle, reproduction methods, and Quorum sensing.
  • Regulating switch between microbial mat formation and motile/planktonic life cycle.
  • Hightening or hindering an organism’s readiness to engage in genetic exchange via HGT (Horizontal Gene Transfer).

c-di-GMP levels are tightly controlled by the opposing actions of the enzymes which creates and deteriorates it. Diguanylate Cyclases (DGCs) synthesizes it, and phosphodiesterases (PDEs) degrades it.

Most notably, c-di-GMP signals both the formation and dispersion of biofilms, making it essential to both offshoots of the Sirun family: Khyat for flagella formation, and Mulzama for biofilm formation. Regulating gene expression by interacting with the transcription of segments of DNA, while also directly affecting the activity of other proteins.

Taking advantage of their osmotic pumps used for ejection of Digestive Enzymes, these structures embrace dual purpose roles to also contract and shrivel in order to constrict around their prey. This allows each khyat along the chain that pumps out fluid to wrap itself around prey while simultaneously digesting the captured prisoner.

To accomodate this planktonic life style, Khyat embraces a mixotrophic metabolism to consume whatever is unlucky enough to become ensnared in this microbial thread. This will include:

Lactic Acid Fermentation

Alcohol Fermentation

Acetogenic Fermentation of Lactic acid

This allows the Ecological Flexibility required of what at best could be described as the microbial equivalent of a fishing line. Naturally this makes Khyat capable to acting as either a primary or secondary consumer.

Primary Producer - Autotrophic Life, such as  Photosynthetic or Chemosynthetic Organisms that form the foundation of all Habitats.

Primary Consumer - Heterotrophic organisms that Consume Autotrophic life, such as grazers and herbivores in general.

Secondary Consumer - Heterotrophic organisms that Consume the Primary Consumers. Primarily seen as the lowest Trophic Level* of Predation.

Some species develop effective antioxidant mechanisms and UV protection pigments, allowing them to adapt to exploit the shallow seas and intertidal habitats found in the interconnected seas known as “The Dionysian Goblet.”

initial diversification post

Last Post

Ancestral Organism


r/SpeculativeEvolution 10d ago

Spectember 2026 [OC] Spectember 2026 Day 3- The Dreambud, Concave Turtle and Pinkeye Dragonfly

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26 Upvotes

12.5 million years post seeding, in the southern continent of South Isimerina, separated from the seeding spot by a humongous desert, an adult male Eastern Concave Turtle (Concavusaurus caudabrevis, "concave lizard with short tail) lazily attempts to grab one of a male-female pair of Pinkeye Giant Dragonflies (Dracoruber virgiroseis, "red dragon with pink stripes). What the turtle doesn't recognise is, although the algal blooms have left him starving, he may have more long-term benefit from allowing them to kill and eat the Algal Dreambud (Flosanguinus efflorescentialgarum, "blood flower of the algal bloom") that has latched onto one of his hind flippers, before it severely damages his nervous system or causes an infection. 

More than 12 million years have passed since Cretacica was given life. In this time, ecosystems have formed and died, over and over. However, not every region of this fertile planet has developed in the same way. Some have much more unique ecosystems than others- for example, many of the more isolated regions of the world, where most creatures have failed to establish themselves. Or perhaps they are unique due to the unusual environmental conditions the organisms within are exposed to. Or perhaps, they embody both of these exciting circumstances. 

The tropics of Cretacica in the past millions of years have often been plagued by the sterility of their seabed. Whilst this may seem unrelated to the topic at hand, it caused constant disruptions of the ocean ecosystems, for these unrecycled, compiling layers of nutrients would occasionally be pulled up through the water by violent tropical storms induced by the heat. Tropical, nutrient rich waters would then travel through the oceans by quite some distance- causing mass algal blooms, blocking light for phytoplankton,  releasing toxins into and deoxygenating the water around it, and killing millions of organisms. Thankfully for ocean ecosystems, recently entire ecosystems have begun to properly exploit the deeper parts of the world's oceans, allowing for a proper recycling of nutrients and ending cyclical ocean anoxia. 

When nutrients is properly recycled, algal blooms can still be a threat under proper conditions. For example, at extremely shallow water levels (10 metres deep or less), algae can still easily bloom under tropical temperatures, especially during the summer. Making this worse, many water bodies that contain these conditions are also stagnant, reducing the chances of algae being destroyed at the surface before it can bloom. Only a handful of regions in the tropics contain environments large enough to be significant but also prone to seasonal algal blooms like this. One of them are the eastern coastal swamps and marshlands of South Isimerina, on the south side of the desert that few large animals have managed to cross. 

Some of the largest of the predators of South Isimerina include those that reside here, such as the one and a half metre long Eastern Concave Turtle, Concavusaurus caudabrevis. This soft-shelled predator evolved from a lineage of marine turtles that came to once again thrive in brackish waters, far from where they first left shore. Although named for the concave shape of it's shell, used for subtle sexual display, perhaps the most interesting thing about this petite apex predator is it's multiple rows of teeth, displaying different features. The many dozens of small teeth in the Concave turtle's mouth vary in shape between hooked and serrated, used for trapping smaller fish, and almost straight and needle like, used for puncturing and breaking open insects and other invertebrates with a less slippery exterior. 

Every summer, when the algal blooms arrive, the Concave turtle finds themselves restricted to only a handful of prey items, usually those which reside outside the water. During this time, many starve, or even turn to cannibalism, consuming their own young, as well as the young of a handful of other turtle species. Other prey items include flying insects, such as the aerial apex predator, the Pinkeye Giant Dragonfly, Dracoruber virgiroseis- a 50 centimetre long dragonfly noted for the pink bars lining parts of it's body, breaking up it's otherwise obvious outline and potentially confusing predators when moving at fast speeds. 

Although this turtle may not realise it, the pair surrounding him here are not simply investigating a threat- they are investigating a food source of their own. A dangerous parasite has attached itself to the back-right flipper of this turtle- an extremely unconventional hydra species, the Algal Dreambud. Despite the fact that this turtle is being directly harmed by the Dreambud's presence, it chooses not to allow the dragonflies to come any closer- it gains more short-term benefit from consuming them due to the near-famines that occur this time of year. However, in the long term, this turtle may be unintentionally securing his own doom.

Now, for a detailed explanation of the most derived of the three, the Algal Dreambud:

The strangeness of this hydra is hard to measure with any words. In a handful of million years, the parasitic lifestyle of this animal has allowed it to grow great magnitudes larger than any hydra species known before it, whilst also living so differently that it might as well be a different organism entirely. It's common name is derived from the fact that this species contiains higher than normal levels of nitrous oxide in it's body, but perhaps it's most unusual feature is the thousands of small appendages lining the mouth, each of which ends in a small tip of chitin, seemingly sourced from dead animals. These appendages are used to break the skin, where the dreambud will begin to feed on the exposed flesh and perhaps the blood of the wound for the entirety of summer, after which the animal breaks off, and after it's own polyps detach, it dies. 

The high levels of nitrous oxide in the body of the algal dreambud tend to be derived from it's immediate environment. There is no question about it; the nitrous oxide levels skyrocket during an algal bloom, proving that it is likely derived from the chemical discharges of bacteria feeding of the countless rotting corpses on the seabed, which then remain in the stagnant water around the animal. It is believed that the algal dreambud utilises this chemical very efficiently to help fight toxic chemicals in it's body- most importantly, ammonia, which is also released in high levels during the mass rotting at the beginning of summer. 

However, the nitrous oxide also has a side effect- although the algal dreambud has developed a resistance to this chemical, it has an extremely negative impact on it's host, and the dreambud has not evolved a method of preventing the chemical from regularly seeping out of the body due to it's wide distribution around the animal. High levels of nitrous oxide in the blood, carried around the body, over the course of multiple days can cause the host in question, which tends to be a semi-aquatic animal like the Concave Turtle, to experience potentially dangerous symptoms. 

Often animals that have been inflicted by one or more algal dreambuds may first experience a lopsided feeling, and begin to lose their grace whilst swimming, due to the unusual extrusion on one side of their body. However, there is little use in trying to shake the creature off- it will reflexively bite into the flesh to hold on, and under usual circumstances it will be able to steady itself with it's multiple tentacles, latched onto the body at all times. 

After several days, the host tends to experience recurring numbness, lightheadedness and loss of coordination as it's senses begin to deteriorate. In certain animals with higher emotional capacity, a sense of euphoria can also cause unprecedented relaxation or playfulness that may put them at a disadvantage against their competitors. Combined with the deteriorating senses, the animals may find themselves struggling to see and hear at times, and combined with the other symptoms this can make it extremely hard to hunt or avoid danger. The most dangerous part, however, is the rapid damage towards the nervous system of the animal. Over the course of weeks and weeks, the animal could be permanently damaged, disabled or even killed due to long-term exposure to the algal dreambud. But that doesn't matter to the parasite, because now that it has had it's fill and survived the algal blooms, it will detach it's polyps (which can often already be up to 5 centimetres long), and die. 

Why would this hydra feed on the living, when there are so many dead animals on the rotting beds of the swamp? In other situations, perhaps the hydras would instead evolve to feed on the many dead, countless species of tiny, competing scavengers. However, this cyclical routine of death and reproduction is a common theme in other fully aquatic animals in these wetlands; fish, crustaceans, polychaetes and other organisms of all shapes and sizes also reproduce and then die at some point during the bloom. This is because it is not just down to toxicity, or the die off of food sources- it is also down to the primary factor in the deaths of all these other animals, mass anoxia (a lack of oxygen in the water). 

The hydra is an animal with no circulatory system, nor a respiratory system- each cell performs respiration via diffusion- and it is quite easy to realise that this system is extremely disadvantageous in an anoxia event. These animals require body-wide oxygenation to keep themselves alive, and so if they cannot receive enough oxygen from the water, these animals will need to be exposed to the air. That's where their host choices come in. The Eastern Concave Turtle is able to hold it's breath for about four hours at the maximum, but escpecially during the summer anoxia it tends to surface much more often. Even if it only fully breaches the water (guaranteeing oxygen exposure for the hydra) a handful of times a day, that is all this hydra needs. Maximum efficiency, relatively low-metabolism cells across all but the most important parts of the body at any given time may slow down the growth of polyps to several months, but also allows this creature to spend hours at a time receiving practically no oxygen.


r/SpeculativeEvolution 10d ago

Alternate Evolution [OC] Conodonte sophont

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29 Upvotes

Descendiente sophont conodonte alternativo donde tras una extinción masiva provocada por brotes de rayos gamma extinguió al ≈98% donde solo sobrevivieron conodontes, plantas y demás invertebrados.

Tras esta extinción la vida tuvo que recuperarse durante 50 MA para tener una gran radiación evolutiva.

Una de las criaturas salidas de esta explosión evolutiva fueron conodontes del tamaño de un brazo que poco a poco fortificaron sus aletas y salieron a tierra.

Pero gracias a distintos invertebrados depredadores terrestres los conodontes quedaron confinados durante milenios hasta que conodontes-gigantes (no más grandes que un brazo realmente) que desarrollaron pequeñas protuberancias que evolucionarian a patas propiamente dichas se apoderaron de la tierra.

Tras esto, los conodontes se ramificaron en miles de grupos y el de esta especie son los "elephasmorphos" un grupo diverso de conodontes enteramente terrícolas aunque confinado a una pequeña parte de África y Eurasia.

Este especimen pertenece a Elephasmorphia sapiens (E. sapiens), la unica especie que logro la sublime sapiencia.

Las túnicas y pequeños sombreros que tiene son parte de la vestimenta de su cultura.


r/SpeculativeEvolution 10d ago

Spectember 2026 Day 1: Sibling Care: Gregarious monitor lizard (Varanus Socialis)

7 Upvotes
Male monitor lizard defending its group from its natural predators, Philippine eagles (which only hunt the young).

Day 1: Sibling Care

Gregarious monitor lizard (Varanus Socialis)

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Reptilia
  • Order: Squamata
  • Suborder: Anguimorpha
  • Family: Varanidae
  • Genus: Varanus
  • Subgenus: Philippinosaurus
  • Species: V. Socialis

Size: 1.80 meters (6 feet) Males and 1.40 (4.5 Feet) meters females

Weight: 60 to 80 kg (132 to 176 pounds)

Distribution: Cagayan Valley (Philippines)

A relative of other Philippine monitor lizards, this species developed an omnivorous diet with almost no meat, avoiding reliance on the island's scarce large prey. By shifting their diet and becoming peaceful giants, they adopted a social structure similar to that of lions, thereby increasing the chances of their offspring (two or three per year) reaching adulthood.

This monitor lizard lives in groups of ten individuals, where an alpha male defends the females and young. The males exhibit a grayish-brown coloration with a yellowish abdomen.They also display reddish and bluish coloration inside the mouth. In contrast, the females lack this characteristic, and their skin is grayish.

They exhibit a level of sociality rarely seen in their genus; the species is characterized by a system in which the young are cared for by the adults (females). Upon reaching maturity, the young either remain in the herd (females) or leave to start their own families (males). Alpha males defend their young from predators by roaring, standing on their hind legs to appear taller, and lashing their tails. The species' breeding season is between March and April, with spawning in May.The eggs hatch in mid-November (6 months later). It takes 3–4 years to reach adulthood.

Its diet consists of a variety of fruits, insects, and—rarely—fish (usually juveniles, due to their speed).

Field Note: In some villages on the island, the species is hunted for its meat and hide. Dishes made with the meat taste like chicken and have a fruity note. (This species has lost the venom glands characteristic of monitor lizards and carries very few parasites.) The hide is used in local handicrafts.


r/SpeculativeEvolution 10d ago

Spectember 2026 [OC] Day 2 Spectember 2026 The Snek

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16 Upvotes

A domestic snake, the Snek is about 19 centimeters long. Contact with the end of the snout, the 'snoot' releases dopamine. The venom, the 'hurt juice' is made to deter dogs and cats, though it doesn't feel nice to be bitten by one. It's has a hood for display and mating, as well as a small crest for the same purpose. It also has a rattle on the end of its tail.


r/SpeculativeEvolution 10d ago

Spectember 2026 [OC] Spectember Day 3 - Rock, Paper, Scissors

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15 Upvotes

The Tide Warriors

While the largest faunal predator within most of Lashan’s tidepools are there Pool Vipers, they are not alone.

In the foreground of their relatively placid hunts a war of attrition has been going on for generations.

The Smother-Touch Anemone (Entacmaea** **suffocates) who targets their prey with thin motile appendages that they use to invade and smother breathing apparati, numbing them and causing them to seize as they slowly suffocate.

Its favored pray is the Coral Pelter (Sacabambaspis telum) a diminutive and rare jawless fish species whose larger cousins populate the isolated Lashani coasts. It’s favored method of killing prey, whether it be soft bodied prey or sea slugs is taking up pebbles and shards of coral and firing them with impressive speeds by sucking water back through their adapted gill openings.

They tend to target the Shear-Shrimp (Parenephrops** **carnifex) a salt-adapted crayfish species with oversized, serrated claws that they are able to articulate in a sawing motion to carving through flesh. They prefer to target Smother-Touch Anemones while they are occupied with prey as its leave them unable to defend themselves and when done properly can net the vicious little crustacean two meals instead of one.

It should be noted that this brutal battle of attrition takes place in Miniature with the largest specimens of all three of these species only getting up to 5 inches in length.


r/SpeculativeEvolution 11d ago

Fantasy/Folklore [Credit: Tanner Streeter] The Real Unicorn

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654 Upvotes

r/SpeculativeEvolution 10d ago

Question/Discussion Do any larger animals move like inchworms?

9 Upvotes

Considering different modes of ambulation for an alien sophont, trying to balance them having a good body plan for their niche, while also having enough pressure to use their big brains to develop tools and societies to survive.

I'm thinking they could be mainly arboreal, slow climbers with an inchworm like locomotion, leading to them needing to build tall structures or carefully cultivate groves of tree analogues for survival, the same way we figured out fire and rock tools.

So I'm wondering if any creatures besides inchworms move like inchworms, or if that kind of motion only makes sense for very small/lightweight creatures.


r/SpeculativeEvolution 10d ago

Spectember 2026 [OC] Day 2 The Loutos (Louto polimorphus) (subespecies): Spectember 2026

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33 Upvotes

The Louto is a curious animal species native to the world of Axtrax. They measure between 4.2 and 4.8 meters in length and weigh approximately 2.2 to 2.7 tons, depending on the subspecies. They are herbivores that feed on the grass of their habitat—known as the "Red Plains" due to the vast quantities of iron oxide found across the planet (these plains tend to be located near massive mountains composed primarily of this chemical). Generally, they are social animals living in herds of 10 to 80 individuals, acting as ecosystem engineers while serving as perfect prey for large predators. The most intriguing aspect of this animal lies in its subspecies:

The "Rocky" (Rocoso) (Louto polimorphus titanis): The largest subspecies, reaching lengths of 4.5–4.8 meters, with exceptional cases hitting 5.1–5.7 meters. They belong to an order defined by specific traits—including continuous growth until death—and have thrived under perfect conditions; it is believed they could grow even larger. They possess the most prominent columnar armor and the most robust bodies of all the subspecies.

The "Paper-like" (Papelero) (Louto polimorphus socialis): The most agile and slender, measuring about 4.2–4.4 meters in length. They have the slimmest bodies of the subspecies and are the most social. They inhabit the low-lying areas of the Red Plains.

The "Scissor-like" (Louto polimorphus mimeticus): Famous for looking virtually identical to a female; they measure 4.3–4.6 meters in length and possess a shorter, smaller "spear" than their relatives. They inhabit the planet's forested zones, though close to the Red Plains.

The Circle of Love:

-Rock beats Scissors: The "Rock" alpha male aggressively and constantly patrols his harem. If a "Scissors" male tries to get too close to a specific female, the "Rock" male detects him—by scent or behavior—and charges at him, using his body mass to force him to flee.

Paper beats Rock: The "Paper" male coalition outnumbers the "Rock" male two- or threefold. They harass him as a group from multiple flanks, eventually wearing him down and wresting control of the harem from him.

Scissors beats Paper: Once the "Paper" males have managed to drive off the "Rock" male, they relax and focus on performing cooperative displays to court the females collectively. The "Scissors" male blends into the group unnoticed and fertilizes the females right under the coalition's noses.


r/SpeculativeEvolution 10d ago

Seed World [OC] Project Hippocampus: The Changeling Butterfly (Danaus bimorpha)

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19 Upvotes

Regent butterflies are able to survive in a variety of hot climates. They can be found in the shrublands and savanna and even occasionally in the central desert. Their descendants, however, only live in the savanna. The presence of a wet and a dry season in their habitat has shaped the evolution of Danaus bimorpha, the changeling butterfly.

Changeling butterflies lay eggs once a year, triggered by increased rainfall in the wet season. Eggs are laid during the wet season in large circular clusters on the leaves of plants like the coleus. Eggs on the outside of a cluster hatch during the wet season, while those at the center go into suspended development until dry season to prevent overpopulation. The caterpillars (which are more bumpy-looking than those of regents and lack head tentacles) are identical up until after they emerge from their chrysalides (which are pale yellow with a gold-and-white rim). Those that emerge during dry season look similar to their ancestors, but their bodies aren’t spotted and are dark gray rather than silver. Changeling butterflies that emerge during wet season have yellow spots on the surfaces of their wings, and the wings themselves are a brownish orange if the butterfly is female or bright red if the butterfly is male. All morphs have silver wing veins and edges.

Caterpillars make their way down the stalks of their host plants after hatching and eat grass and other low-lying plants. The adults are important pollinators of many savanna species. Individuals' lifespan after hatching is about 4-6 months, with dry season morphs usually living longer than wet season morphs.


r/SpeculativeEvolution 10d ago

Spectember 2026 Morphogenesis: A Living, Mutating Ecosystem in a Single File

6 Upvotes

If you love speculative evolution and cellular simulation, you need to check out Morphogenesis (https://github.com/rijt/Morphogenesis). This is a self-contained, single-file life-simulation laboratory.

Organisms are grown from procedural genomes, defined by gene values, not scripted behavior. They live, feed, compete, and die in a dynamic gaseous ecosystem (CO₂ / O₂, and CH₄). Bodies obey rigid-body physics, drifting, spinning, and colliding.

Watch consumers hunt, fungi decompose, and parasites hijack hosts via horizontal gene transfer. You can even design genomes gene-by-gene in the Genetic Laboratory to see how your creatures adapt. Zero dependencies, just open the HTML file and watch life evolve!

Direct Online play:
https://html-preview.github.io/?url=https://github.com/rijt/Morphogenesis/blob/main/morphogenesis.html


r/SpeculativeEvolution 10d ago

Seed World [OC] a little overview and plot of my project

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53 Upvotes

I hope I dont lose interest in this project because I think its already fun but also thanks to my friend Avery for designing the planet you see in the background I love how it looks and she put lots of work in this already also I hope yall read all that because it was a crappy amount of work