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Difficulty: MediumMorphological and Physiological Adaptations to Environments

In wading birds standing in ice-cold water, counter-current heat exchange between adjacent arteries and veins in the legs cools outgoing arterial blood before it reaches the feet, thereby reducing conductive heat loss to the surrounding environment.

Answer: Answer

Answer

True
Counter-current heat exchange is a classic morphological and physiological adaptation in wading birds. By running warm arterial blood past cold venous blood in the leg's vascular network (rete mirabile), heat is transferred back into the body core before arterial blood reaches the foot. This keeps foot temperature low, lowering the thermal gradient against cold water and conserving body heat.

Step-by-Step Solution

1
Identify the primary environmental challenge faced by wading birds in cold aquatic habitats.
Cold water quickly absorbs body heat through exposed, non-insulated extremities like legs and feet.
Maintaining homeothermy requires organisms to minimize thermal loss across surfaces exposed to low temperatures.
2
Analyze the anatomical and physiological mechanism of counter-current exchange in limbs.
Arteries carrying warm blood from the core run immediately parallel to veins carrying cold blood returning from the feet.
Heat naturally flows down the thermal gradient from warm arterial blood to cooler venous blood.
3
Determine the functional outcome on foot temperature and environmental heat exchange.
Arterial blood is pre-cooled prior to reaching the foot, reducing the temperature difference between the foot and water.
Conductive heat loss rate is directly proportional to the temperature differential between an organism's surface and its surroundings.

Key Concept

Counter-current Heat Exchange for Thermoregulation
Estimated Time:1m 0s
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Topics

Morphological and Physiological Adaptations to Environments

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