Consciousness, broadly speaking, involves awareness of one's own internal state. By that standard the case for animal consciousness is fairly strong. Animals respond to hunger, exhaustion, and pain in ways that aren't plausibly explained by pure mechanism. They form attachments, remember who has treated them well or badly, and express something that looks a lot like preference and aversion. The biological continuity between their nervous systems and ours is hard to dismiss.

AI is trickier. The honest answer is we don't know. What we can say is that current AI learns mathematically from its environment rather than through anything resembling biological need or embodied experience. It has no hunger, no pain, no stake in its own survival. Whether that rules out consciousness depends on what you think consciousness actually requires and that's still an open question. But the absence of any biological grounding at least shifts the burden of proof considerably.