Module 4

Diving Physiology

Penguin diving physiology parallels marine mammals: muscle myoglobin at ~4 g per 100 g muscle (10× human), bradycardia to 20 bpm at depth, air-store lung compression, and aerobic dive limits enforced by total oxygen stores. Emperor penguins dive to 565 m and 32 minutes (Kooyman 1992), approaching Weddell seals on a much smaller body size.

1. Oxygen Storage

Compared with flying birds, penguins have elevated blood volume (100 ml kg^-1vs. ~60 ml kg^-1 in typical birds), haemoglobin (20 g dL^-1), and muscle myoglobin (4 g per 100 g muscle; Kooyman 1999). Mirceta 2013 showed that the myoglobin of diving birds and mammals carries convergent positive surface charges that prevent self-aggregation at the high concentrations required.

2. Diving Reflex

Heart rate drops from ~175 bpm at surface to ~20 bpm during deep dives (Meir 2009). Selective peripheral vasoconstriction redirects oxygenated blood to brain and heart. Core temperature drops slightly during long dives — a controlled hypothermia that reduces tissue O₂ consumption (Ponganis 2003).

Simulation: Dive Repertoire

Python

script.py31 lines

import numpy as np, matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt

# Penguin diving repertoire
species = ['Emperor','King','Gentoo','Adelie','Chinstrap','Little']
depth_max = [565, 343, 200, 175, 121, 67]
duration_max = [32, 9.2, 7, 6, 4, 2]

fig, (ax1, ax2) = plt.subplots(1, 2, figsize=(14, 5), facecolor='#0a0a1a')
for ax in (ax1, ax2):
    ax.set_facecolor('#111827'); ax.tick_params(colors='#cbd5e1')
    for s in ax.spines.values(): s.set_color('#334155')
    ax.grid(True, color='#334155', alpha=0.3, axis='y')

ax1.bar(species, depth_max, color='#60a5fa', edgecolor='#bae6fd')
for i, v in enumerate(depth_max):
    ax1.text(i, v+10, f'{v} m', ha='center', color='#bae6fd')
ax1.set_ylabel('Max recorded depth (m)', color='#cbd5e1')
ax1.set_title('Penguin dive depths', color='#bae6fd', fontweight='bold')

ax2.bar(species, duration_max, color='#fbbf24', edgecolor='#bae6fd')
for i, v in enumerate(duration_max):
    ax2.text(i, v+0.3, f'{v:.1f}m', ha='center', color='#bae6fd')
ax2.set_ylabel('Max duration (min)', color='#cbd5e1')
ax2.set_title('Dive duration', color='#bae6fd', fontweight='bold')

plt.tight_layout()
plt.savefig('output.png', dpi=120, bbox_inches='tight', facecolor='#0a0a1a')
print('Emperor 565 m / 32 min (Kooyman 1992)')
print('Myoglobin 4 g/100g muscle (human 0.4 g/100g)')

Click Run to execute the Python code

Code will be executed with Python 3 on the server

3. Species Variation

Dive capability scales with body mass: emperor > king > gentoo/Adélie > chinstrap > little penguin. Adélies specialise on near-surface krill; gentoos exploit mid-water fish; emperors pursue fish at mesopelagic depths. Diet segregation partitions the resource across co-occurring species.

Key References

• Kooyman, G. L. et al. (1992). “Diving behavior and energetics of emperor penguins.” J. Exp. Biol., 168, 1–14.

• Meir, J. U., Stockard, T. K., Williams, C. L., Ponganis, K. V. & Ponganis, P. J. (2009). “Heart rate regulation and extreme bradycardia in diving emperor penguins.” J. Exp. Biol., 212, 3143–3151.

• Mirceta, S. et al. (2013). “Evolution of mammalian diving capacity traced by myoglobin net surface charge.” Science, 340, 1234192.

• Ponganis, P. J. (2015). Diving Physiology of Marine Mammals and Seabirds. Cambridge UP.

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