Why can this carnivore not attack this species? Bug or not?

[jaykel]

Carnivore
Traits: Carnivore, Intelligence, Fat Tissue
Pop: 4
Body: 6

Other Species
Traits: Foraging, Cooperation, Hard Shell
Pop: 4
Body: 2

I would think intelligence allows the carnivore to bypass hard shell, so I'm not seeing why an attack isn't possible. Thought?

[BoardMasterGamer]

Intelligence requires you to have a card in hand to discard. Did you have one available?

[Cile]

Did it have a neighbor with Warning Call?