Star Trek: 10 Things You Didn’t Know About Vulcans
7. Don't You Ever Sweat?
Resembling humans with slightly pointier ears on the outside — a similarity explained in canon by the likes of Hodgkin's Law of Parallel Planetary Development, the Arretans, and those aliens from The Chase — Vulcans have a fairly distinct biology on the inside. Doctor McCoy's heart might have been in the right place despite his caustic humour but, in a manner of speaking, Spock's was not.
Aside from their heart being where their liver 'should be,' we know that Vulcans have green blood thanks to (copper-containing) haemocyanins, although on Earth these normally give a blue colour in their oxygenated state. Vulcans can also function (to a degree) without a brain, go without sleep and water for several days, and, further adapted to their desert planet, possess inner eyelids (or nictitating membranes) to protect against the glare of the Vulcan sun.
In the Star Trek: Voyager episode The Haunting of Deck 12, Tom Paris asks the titular question, to which the anti-perspirant Tuvok replies, "Not unless the temperature reaches 350 degrees Kelvin". 350°K is 76.85°C (170.33°F) or, in other words, "as hot as Vulcan".
According to the Star Fleet Medical Reference Manual (1977), however, Vulcans lack sweat glands as a water-saving measure; their epidermis is actually capable of absorbing water from the air. Heat loss is achieved instead via specialised "hyalothermonic" cells in the dermis, and through an extreme dilation of the blood vessels, which gives a greater surface area for cooling. Vulcans also have a mind-boggling average heart rate of 242 BPM and blood pressure of 80/40.