An interesting side note is that the Healesville platypus presenters said that there are 15 wild platypus living in the stream running through the grounds.
Platypus are actually quite common in suitable habitat. They can be found quite close to the centre of the city since the Yarra was cleaned up. We have even had them in our stream. Of course they are very secretive and difficult to observe.
I think that Platypus House in Tasmania have bred them. I seem to recall something about them saying they had when I visited 3 years ago.
As for my question about San Diego potentially getting platypus, this recent thread shows it is indeed a realistic possibility: San Diego Zoo - Platypus...
I looked into this (via the mine-field that is Google). Lots of Tripadvisor reviews mentioning or implying how Platypus House have bred or do breed platypus, so I think that the public talks there must be either vaguely-worded or deliberately misleading. I found a newspaper article from as far back as 2005 about the place setting up a "breeding tank" (the "breeding tank" is also mentioned in some Tripadvisor reviews) but I also found an article from January 2017 - so just a few months ago - which doesn't explicitly say they haven't yet bred them but it seems quite clear from the contexts. Pressure on platypus numbers | Photos, video
Interesting. I was going to say that I wasn't sure whether they said they had bred, or whether they hoped to because my visit was 3 years ago, but if other people have said they make that claim you may be right. Either way, it was quite a strange setup, being situated on a jetty out over the sea. It also houses a few echidnas which you can pat during the presentation.
Of note to platypus fans is the 769-page magnum opus The Management of Wild Mammals in Captivity (1964 - Lee S. Crandall) which of course is already in the collection of all true zoo enthusiasts. It is one of the most interesting books ever written about animals and there are 10 pages all about the captive history of the platypus. Crandall spent more than 60 years working at the Bronx Zoo and his details in regards to the platypus are extraordinary. Cost of food, names of specimens, David Fleay's animals, diet, measurements of animals and their enclosures, etc. There is far more information than I will provide here. 'Cecil' and 'Penelope', a pair of platypus captured in 1946, both lasted until 1957 and thus spent 11 years in captivity. The Bronx Zoo then obtained a trio of platypus (1.2) on June 7th, 1958, but "these later arrivals failed to adapt, the survivor living only to March 25, 1959." If the San Diego Zoo Safari Park puts a pair of platypus on exhibit next year then it will be exactly 60 years since the species has been seen in the USA.
FYI - if anyone is in Australia and really wants to see Platypus - I strongly recommend Healesville Sanctuary near Melbourne. Their "Platypussary" is one of the best exhibits I've seen and on multiple visits we've witnessed them frolicking in broad sunlight. None of those dingy caves where you are hard pressed to see them swimming around murky water. Also, their indoor viewing area is a lot larger than most facilities and makes for good viewing. Platypussary - Sep 2008 by Simon Hampel posted 3 May 2009 at 12:08 AM Platypus - Sep 2008 by Simon Hampel posted 3 May 2009 at 12:09 AM Platypus - Sep 2008 by Simon Hampel posted 3 May 2009 at 12:09 AM Platypus - Sep 2008 by Simon Hampel posted 3 May 2009 at 12:09 AM
This exhibit has been modified now to create a presentation area in the foreground while the background (the part in your first photo) is used for encounters. The presentation is really great and involves a glass fronted pool in front of some tiered seating where the keeper (in waders) gets into the pool and shows off some behaviours. You can get better views of the platypus than anywhere else I've ever seen them.
That platypus show was a highlight of my visit to Healesville in 2017. They also bring out other wetland species like yabbie, a duck, and a turtle (don't remember what species) and talk about the platypus's habitat as well as its natural history.
You would all most likely be horrified to learn that I rarely bother to enter the platypus house when visiting Melbourne Zoo.
Melbourne Zoo's platypus is very active though, and always puts on a good show in its nocturnal enclosure. The "darkness" at Healesville is less apparent though, as it is a longer building with a number of exhibits that allow visitors' eyes to adjust before they get to the platypus enclosures. The platypussary is only viewable during shows (and encounters - Wade with a Platypus), but definitely provides great views of the animals.