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Verglas

A frozen ocean moon circling a giant planet, sealed under a kilometres-thick ice shell that blocks nearly all sunlight. Tidal flexing keeps a dark, salty sea liquid beneath the ice, warmed and fed by mineral-rich vents on the seabed. Gravity is light and the cold water oxygen-poor, so life clings to the under-ice ceiling above and the vent fields far below.

Veridian Swift-Fin

Evo 4FishEats plantsSurfaceResilient

Shaped by 🦈 new predator

A smaller, sleeker fish with rapidly beating pectoral fins, adapted to graze Rime-Mat while evading predators.

streamlined bodyenhanced pectoral finsreduced heat-exchange surfaces12 cmlow-light senses
Size
12 cm
Diet
chemosynthetic biofilm grazer
Habitat
underside of the ice shell
Moves by
darting swim

Why it evolved

The introduction of a new predator necessitates increased evasive capability. The Veridian Swift-Fin evolves a more streamlined body and significantly enlarged, rapidly oscillating pectoral fins to achieve greater burst speed and maneuverability, allowing it to escape threats like the new predator. This adaptation comes at the cost of reduced heat-exchange surfaces, making it slightly more vulnerable to temperature fluctuations near vents, a minor concern in the generally stable, cold water of the under-ice ceiling environment.

What changed from Veridian Heat-Gill

Gained:+ streamlined body+ enhanced pectoral fins+ reduced heat-exchange surfaces+ 12 cm
Lost:biomineralized gill filamentstoxin-resistant bloodexpanded heat-exchange surfaces15 cm
  • Size: 15 cm 12 cm
  • Moves by: hovering swim darting swim
🐟FrostgillEvo 1🐟Veridian Fr…Evo 2🐟Veridian He…Evo 3🐟Veridian Sw…Evo 4
  • resilient
  • strained
  • fragile
  • β˜… canon
  • 🧬 hybrid
  • πŸ’€ extinct
Drag or scroll to move Β· Tab + Enter for keyboard Β· click to select, double-click to openView as list4 species

You choose the situation, not the result. Selection acts on Veridian Swift-Fin; the descendant appears above.

Climate

Resources & space

Predators & life

Habitat & extremes

Mate Veridian Swift-Fin with another branch of the same lineage to make a hybrid.