Oxygen consumption by ammocoetes of the lampreyGeotria australis in air

Abstract

When covered by moistened lint-free gauze, the larvae (ammocoetes) of the lampreyGeotria australis survived, without apparent discomfort, for 4 days in water-saturated air at 10, 15 and 20°C. In air, the mean standard rates of O₂ consumption of medium to large ammocoetes ofG. australis (000000000;=0.52 g) at 10, 15 and 20°C were 14.5, 35.7 and 52.1 μl·g⁻¹·h⁻¹, respectively. At 15°C, the slope of the relationship between log O₂ consumption (μlO₂·h⁻¹) and log body weight for ammocoetes over a wide range in body weight was 0.987. TheQ ₁₀s for rate of O₂ consumption between 10 and 15°C, 15 and 20°C and 10 and 20°C were 4.9, 2.9 and 3.6, respectively. Our results and observations of the ammocoetes suggest that, when out of water, larvalG. australis derives most of its O₂ requirements from cutaneous respiration, particularly at lower temperatures. This would be facilitated by the small size and elongate shape (and thus a relatively high surface-to-volume ratio), low metabolic rate, thin dermis, extensive subdermal capillary network and high haemoglobin concentration of larvalG. australis.