“Sentience has broader and narrower senses. In a broad sense, it refers to any capacity for conscious experience. […] In a narrower sense, it refers to the capacity to have valenced experiences: experiences that feel bad or feel good to the subject, such as experiences of pain and pleasure”.
Also, here is an article about the Cambridge Declaration on Consciousness that strongly supports the claim that sentience is a trait shared by most, if not all, of the animal kingdom.
One of the 5 animals believed to have the capacity for sentience? I think you mean consciousness?
The entire mammal kingdom is widely considered sentient. As are many other groups like fish and insects.
Even with consciousness it’s stretching it is very conservative to estimate just 5 species.
“Sentience has broader and narrower senses. In a broad sense, it refers to any capacity for conscious experience. […] In a narrower sense, it refers to the capacity to have valenced experiences: experiences that feel bad or feel good to the subject, such as experiences of pain and pleasure”.
Taken from https://academic.oup.com/book/57949/chapter/475703402
Also, here is an article about the Cambridge Declaration on Consciousness that strongly supports the claim that sentience is a trait shared by most, if not all, of the animal kingdom.
https://www.animal-ethics.org/10th-anniversary-of-the-cambridge-declaration-on-consciousness/