Leatherback Turtle Dive Physiology Simulator (2D)

Dive plan

Target depth 1280 m

Surface water temp 26°C

Jellyfish hunting effort 50%

Gigantothermy ON

Run

Live physiology

Depth

0 m

Zone

Sunlit

Heart rate

25 bpm

O2 store

100%

Core temp

28°C

Water temp

26°C

Dives completed

Anaerobic ascents

Aerobic dive — O2 store still covers the cost Anaerobic — O2 store exhausted, forced ascent

The physiology this models

The 3D Leatherback Turtle Deepdive animates the same 1280 m record dive but tracks only position and jellyfish caught. This 2D companion turns the dive into the real budget a leatherback actually manages: a finite blood/muscle oxygen store, a bradycardic heart that slows to stretch that store, and a body kept warmer than the water around it by counter-current heat exchange in the flippers (gigantothermy) — the reason a "cold-blooded" reptile can hunt jellyfish in near-freezing water.

O2 use rate    = base * (HR / HR_surface) * coldPenalty * (1 + huntingEffort*0.4 during hunt)
Bradycardia    HR drops from ~25 bpm at the surface to ~4-6 bpm while submerged
Water temp(d)  = surfaceTemp - (surfaceTemp - 4C) * smoothstep(0, 600m, d)
Core temp      relaxes toward (waterTemp + insulationOffset) with time-constant tau
                 gigantothermy ON:  offset ~8C, tau ~220s (slow heat loss)
                 gigantothermy OFF: offset ~2C, tau ~25s  (fast heat loss, ectotherm-like)
coldPenalty    = 1 + clamp((idealCore - core)/10, 0, 1) * 0.6  (cold muscles cost more O2 per stroke)

Target depth — deeper dives cost more descent/ascent time at the same swim effort, extending exposure before the O2 store is replenished at the surface.
Surface water temperature — colder water drops the thermocline faster, so the turtle spends more of the dive fighting to stay warm.
Jellyfish hunting effort — the burst-swimming needed to catch prey once at depth adds directly to the O2 consumption rate, at the point in the dive where the store is already lowest.
Gigantothermy toggle — turn it off to see what happens to a reptile-sized ectotherm at 1280 m: core temperature collapses toward freezing water temperature, cold muscles burn oxygen faster, and the aerobic dive limit is reached long before the turtle nears the bottom.

Crossing the aerobic dive limit does not end the dive — it switches metabolism to anaerobic (lactate-producing) mode, forcing an immediate ascent, exactly as it does in real breath-hold divers.

Sunlit zone Twilight zone Abyssal zone

Depth profile & oxygen budget

Idle

ADL: —