Chapter 11: Flora and Fauna of Théxar — Planetary Ecology

"Six legs run across the plain, four wings cleave the sky, three eyes scan for prey. Théxar is a symphony of life, where each part is written for its performer." — From the "Encyclopedia of Life Forms," Institute of Xenobiology Shan-En, +3 200 Y.U.

Related sections: → see [Ch.03, "Planet Théxar"], → see [Ch.04, "Biochemistry"], → see [Ch.05, "Species Xha'Ruun"]

Introduction

The biosphere of Théxar is one of the richest in the known part of the galaxy. An estimated 8 to 12 million species exist on the planet, of which only ~2.8 million have been described (~28%).

Six limbs are the dominant body plan for large animals. However, Théxar's evolution also produced other solutions: four- and eight-limbed forms, radially symmetric organisms, and pseudopodial giants.

This chapter is an overview of Théxar's living world: from microscopic bacteria to giant ocean filter-feeders, from deserts to ice caps.

11.1 Biogeography of Théxar

11.1.1 Biogeographic Kingdoms

Théxar is divided into 3 biogeographic kingdoms (corresponding to the continents), each with a unique set of species:

11.1.2 Vertical Zones

Fig. 11.1. Vertical distribution of life on Théxar. Each zone has a unique set of adaptations.

11.2 Microorganisms and Protozoa

11.2.1 Bacteria and Archaea

Théxar's bacteria are the foundation of all ecosystems. They participate in key biogeochemical cycles.

Unique group — silicon bacteria (Silobacteriae): use silicon in the cell wall, creating microscopic glass shells. They are the primary soil-formers on Théxar.

11.2.2 Protozoa (Xa'xhal — "living dust")

Théxar's unicellular organisms include flagellates, amoeboid, and ciliate forms. A distinctive feature is the presence of Si-channels in the membrane of ~60% of species, providing more efficient ion transport.

11.3 Plant Life (Xa-The — "life of the earth")

11.3.1 General Characteristics

Théxar's flora is adapted to the Khar'Vex spectrum (→ see [Ch.02, "Khar'Vex"]). The dominant photosynthetic pigment is chromophyll (absorption peak 570 nm).

KEY FACT

Théxar's foliage has a blue-violet and silvery hue, not green. This is a direct consequence of the star's spectrum: chromophyll absorbs orange light (570 nm) and reflects blue-violet. The Xha'Ruun eye sees these colors as tones of "living silver."

11.3.2 Main Plant Groups

Tree Forms

Shrubs and Grasses

11.3.3 "Silicon" Plants

A unique group that uses silicon for structural support:

Fig. 11.3. Cross-section of a silicon stem. Silicon fibers (SiO₂) provide rigidity and protection against herbivores.

Silicon plants are common in arid regions (Vexar, southern Rhuval), where competition for water is high and UV protection is critical.

11.4 Animal Life

11.4.1 Class Thermochromadae — Dominant Taxon

The class Thermochromadae ("warm-colored") — an endemic vertebrate class of Théxar, to which Xha'Ruun belong (→ see [Ch.05, "Species Xha'Ruun"]). Includes ~24,000 species — from small reptile-like (0.24 ша) to giant herbivores (9.8 ша).

Common characteristics of Thermochromadae:

• Hexapodal symmetry (6 limbs)
• Chitinous-bony skeleton
• Double circulatory system (2 hearts)
• Cutaneous thermoregulation through chromatophores
• Cold-blooded (basal) / warm-blooded (higher taxa)

Evolutionary Tree of Thermochromadae

Fig. 11.4. Simplified evolutionary tree of class Thermochromadae — the dominant animal group of Théxar.

11.4.2 Main Orders of Thermochromadae

Predators

Fig. 11.5. Plains Tiger — apex predator of Théxar's savannas.

Herbivores

Kharru Group (Xa-ruunidae)

Kharru — the most significant animal for Xha'Ruun (→ see [Ch.07, "Domestication"]). Domesticated ~−10,200 Y.Civ.

11.4.3 Aquatic Fauna

Ocean Thalas (Northern)

KEY FACT

Giant Filter-feeder (Thal-mor) — the largest animal on Théxar (up to 30.5 ша, ~48,485 кх). Its sieve-mouth filters plankton from the water. Inhabits the surface waters of Thalas. Migrates up to 1,626 мо per year, following phytoplankton blooms.

Deep-sea Communities

In the ocean depths (below 3,658 ша), ecosystems are based on H₂S chemosynthesis (→ see [Ch.04, "Hydrogen Sulfide Metabolism"]). 6 hydrothermal vent fields support unique communities:

• Tube worms (Si-skeleton, length up to 2.4 ша)
• Blind crabs (8 limbs, chemoreception)
• Bioluminescent jellyfish (blue-green light through xanthosine)

11.5 Food Chains and Trophic Levels

11.5.1 Terrestrial Food Chain

Fig. 11.6. Typical terrestrial food chain of Théxar.

11.5.2 Trophic Features of Théxar

11.5.3 Sulfur Cycle

A unique feature of Théxar's ecosystems is the active sulfur cycle (→ see [Ch.04, "Hydrogen Sulfide Metabolism"]):

Fig. 11.7. Sulfur cycle of Théxar. H₂S is not a toxin but a key metabolic substrate, closing a separate energy cycle.

11.6 Unique Ecosystems

11.6.1 Equatorial Jungles

Cover ~10% of the planet's surface. Characterized by:

Six-layer forest structure:

1. Emergent (>98 ша) — giants (Six-winged Oak)
2. Upper canopy (49–98 ша) — main crowns
3. Middle canopy (18–49 ша) — lianas, epiphytes
4. Lower canopy (6–18 ша) — shade-tolerant
5. Understory (1.2–6.1 ша) — shrubs
6. Forest floor (0–1.2 ша) — mosses, ferns, bacteria

11.6.2 Cave Ecosystems

Karst formations of Kharak and Vexar contain isolated underground ecosystems (total area ~9,914 мо²). Some caves have been isolated from the surface for millions of cycles.

Characteristic species:

• Blind Six-legged Crab (Xhel-kreb) — colorless, 17 па
• Cave Filter Worm (Xhel-thal) — 0.61–3.66 ша
• Bioluminescent Moss (Xhel-khar) — faint blue glow

11.6.3 Hydrothermal Oases

In the Gharra ocean, at depths of 0.71–1.52 мо, around 6 hydrothermal vent fields (black smokers, T up to 252°X) exist ecosystems completely independent of photosynthesis:

Fig. 11.8. Hydrothermal oasis — a completely isolated ecosystem based on H₂S chemosynthesis.

11.7 Extinctions and Paleontology

11.7.1 Mass Extinctions

In Théxar's history, 5 major mass extinctions have been recorded:

11.7.2 Impact Event −250 Million Cycles

The largest extinction — an asteroid impact 3.05 мо in diameter in the Gharra ocean (250 million cycles ago). The crater (65 мо in diameter) is now a marine basin.

Consequences:

• Tsunami up to 2,440 ша high
• Winter lasting 15 years
• Extinction of ~70% of species
• Vacated ecological niches → accelerated evolution of Xha'Ruun ancestors

11.8 Xha'Ruun and Ecology

11.8.1 Ecological Ethics

The Xha'Ruun attitude toward nature is shaped by historical experience (→ see [Ch.07, "Crisis Era"]):

1. The "six-step" principle — before any large-scale intervention in nature, consequences are assessed for 6 generations ahead
2. Species reserves — 12% of the planet's area is protected
3. Asteroid mining — metals are mined in space, not on the planet's surface
4. Reintroduction — successful restoration of 8 species exterminated during the Crisis Era

11.8.2 Economics and Ecology

Chapter 11 Summary

Key Conclusions

1. Théxar's biosphere numbers ~8–12 million species, of which ~2.8 million are described
2. 6 limbs is the dominant body plan for large animals (class Thermochromadae)
3. Chromophyll (peak 570 nm) — main plant pigment; foliage has blue-violet color
4. Sulfur cycle — supports ecosystems using H₂S as a substrate at physiological concentrations; excess is harmful
5. 5 mass extinctions, the largest — impact (−250 million cycles, −70% of species)
6. Giant Filter-feeder (30.5 ша, 48,485 кх) — largest animal
7. Xha'Ruun ecological policy — one of the most successful: no recorded extinctions between 2100 and the historical survey of 4028
8. 12% of land — protected areas, 8 species successfully reintroduced

Connections to Other Chapters

• → see [Ch.03, "Biomes"] — map of biomes and climate zones
• → see [Ch.04, "Biochemistry"] — biochemical foundations of Théxar life
• → see [Ch.05, "Species Xha'Ruun"] — Xha'Ruun as a biological species
• → see [Ch.07, "History"] — ecological collapse of the Crisis Era
• → see [APP:bio-ref] — biological species reference