>>533854114
Just cause
Animals on terra are categorized mostly by group as opposed to speciese

If it gives milk its a cystybeast
If its a bird its a fowlbeast
Fish are finbeasts
And rodents are muskbeasts
Work animals are generally called burdenbeasts
No not all animals in these categories look the same either as there can be some variation.
All this is covered on pages 71-85 of the lorebook

I think crabs and bugs are the only ones that dont follow this rule