Amazing how many people take these ads seriously. Every now and again people put in silly ads. Sometimes they are put up by people wanting to be trouble makers, some people just have too much time on their hands and some people just have overactive senses of humour.
A few Tyranosaurus rex have been advertised over the years, sometimes they are stubborn feeders etc. I once put an ad in for a fuzzy kwumpledump, something along the lines of "great pet, easy to care for, very affectionate, gets on well with cats, dogs and other pets $15". I put the phone number of the office at school, it ran hot for days. You might find that the number of the anaconda ad is for DSE or something.