Vertebrates don't have a single, physical "thermostat" like a device. Instead, their temperature regulation is controlled by a complex interplay of several structures and processes within the hypothalamus of the brain.

Here's a breakdown:

* Hypothalamus: This area of the brain acts as the thermostat control center. It receives information about body temperature from sensors in the skin, internal organs, and the blood.

* Sensors: These receptors detect changes in temperature and send signals to the hypothalamus.

* Thermoregulatory Mechanisms: Based on the information received, the hypothalamus triggers various physiological responses to maintain a stable body temperature. These include:

* Sweating: Cooling the body by evaporation.

* Shivering: Generating heat by muscle contractions.

* Vasoconstriction/Vasodilation: Adjusting blood vessel diameter to regulate heat loss or retention.

* Behavioral adaptations: Seeking shade or sunlight, adjusting clothing, etc.

So, while there's no specific physical thermostat, the hypothalamus functions as the central controller for temperature regulation in vertebrates.