Ventilation and oxygen consumption in the spotted stargazer Genyagnus monopterygius†

An abstract of this paper was published in the Proceedings of the Physiological Society of New Zealand 1: 35 (1981).

Abstract

As with other benthic fish which bury themselves in sand, in Genyagnus monopterygius it is the branchiostegal apparatus which makes the major contribution to ventilation of the gills. The prolonged abduction of the branchiostegal membranes draws water in through the mouth, and exhaled water moves away from the fish through mucus‐lined channels in the sand. The steady and continuous flow of water during ventilation may avoid detection of the stargazer by prey or predators. Associated with its sluggish habits and the low gill surface area available for gas exchange, Genyagnus has a low rate of oxygen consumption (15.8 ml kg^‐1 h^‐1 for a 100 g fish at 17°C). At partial pressures of oxygen (PO2) below 6 kPa (45 mm Hg) oxygen consumption is reduced, but the fish does not emerge from the sand until the PO2 falls below 2 kPa. There is evidence that the fish can sustain an oxygen debt. Respiration in the stargazer is discussed in relation to the fish's ability to withstand temporary hypoxia when it is stranded above the water level in the intertidal zone.

Key words:

• Genyagnus monopterygius
• Uranos‐copidae
• spotted stargazer
• respiration
• oxygen consumption
• hypoxia
• behaviour
• respiratory organs
• oxygen

Notes

An abstract of this paper was published in the Proceedings of the Physiological Society of New Zealand 1: 35 (1981).