TL:DR - last line.
Adding on, I'd like to add this (under Behind the Scenes). It may be unreliable, but let me elaborate.
Many things could detect the Cloak, as we see in the series, such as the eye that Moody possesses, and the Marauder's Map. Now, the last bit sounds interesting.
It was also unable to hide Harry from creatures able to sense location by methods other than primarily sight, such as Dementors and Nagini.
Animals that use senses to roam could be able to see under the Cloak (possibly echo location, and snakes).
Dementors can as well, which may lead to snakes being able to.
"Dementors can’t see, you know. . . .” He swallowed. “They feel their way toward people by feeding off their emotions" - Sirius
Emotions such as fear can be sensed by Dementors - if you possess fear, they may be able to know where you are due to this, Cloak or not. As it only protects the user from some spells and sight, I'd assume the latter is correct.
Although different, Mrs. Norris, and Crookshanks may have sensed the presence of the Cloak as well.
As Dementors can sense Cloaks via a way of sensing fear, it reinforces the statement that snakes can sense the Cloak via smell, and possibly heat.