
Quoting
BOR
Consult a personal injury attorney.
IF a protusion is not "open and obvious" as to make no mistake it is there, liability may be imputed to the zoo, yes.
A zoo is unique as a business. It must assume that it's customers are/will be walking WHILE looking at the animals.
Liability may also be unique, or in a particular case, assignable by %, comparitive or contributory negligence, whatever your state recognizes.
You may be 40% liable, the zoo 60%. I am just posting as an example, as the verdict can go 3 ways, a dismissal, a verdict for you what is plead for, or a reduced amount, or a verdict assigning liability.
"General" premises liability laws state a "business is not an insurer of a business invitee's safety". However, that is not absolute in nature.