Rhydian didn't have the guts to disobey Mira's orders, nor did she have a reason to. These two beasts came here to kill her, after all. If Mira wanted to return the favor, then she was all for it.
Without Mira needing to say anything else, she dropped from the sky onto the Earth Titan Bear's back, who didn't even realize Rhydian had moved until he felt something land on him! Regaining his senses, he shifted his attention away from Mira, not realizing she had 9-tails, and onto the thing attacking him. In
*ROOOOOOOOOOOOOOOOOOOAAAAAAAAAR!*
He released a thunderous roar in rage and used his Qi to turn all the hair on his back into tiny yet durable Earth Needles, which weren't as simple as just being sharp. This is one of its defense mechanisms. With its large size, his back is one of his major weak points, as he can't see or reach it. If his species didn't have a way to counter this, they would have gone extinct.