Slaken

Slaken  are huge reptilians that are inhabit planet Lumina along with the Loomish.

Biology
They are huge green reptilian cave-dwellers that exhaled fire. The males of this species are maternal by nature, and at least one adopted a group of the child-like Loomish.

History
When the Doctor and Martha visited a jungle on Lumana, they were conned by the Loomish into believing that they needed protection from the Slaken which wanted to eat them. (DWBIT: House Pests)