Hiya! I have a question. Why is there seemingly such a difference in "quality" between marine mammal enclosures and land mammal enclosures? I've always found it confusing that, for example, tigers in zoos usually have enclosures that mimic their natural habitat, but often all dolphins have is concrete/glass + water. Even fish often have more "natural" enclosures than they do! So I was just wondering if there's any reason for this difference? Thank you for any help, Have a great day :)
There are actually a bunch of reasons, so that’s a really good question!
Let’s start with the simplest. Think of the major nature documentaries you’ve probably seen - the wide-angle shots of cetaceans underwater probably have looked something like this:
Large, deep marine mammal exhibits are trying to replicate this sort of habitat - the open water column. For a lot of cetacean species, even if they do dive deep, they don’t generally spend a ton of time interacting with things on the bottom of the ocean, so that hasn’t been built into the design. Exhibits for cetacean species that tend to spend more time around reefs (which I’ll touch on a bit later) and non-cetacean marine mammals who live in shallower or more coastal habitats will have more rock-work and haul out areas. With terrestrial mammals, there’s all sorts of unique terrain features that can be replicated in a habitat, but for pelagic cetacean species… you’ve just got a lot of water. You see this with fish, too - reef fish have super complicated tank furniture with lots of nooks and crannies, because they use them, but pelagic fish like the tuna at the Monterey Bay Aquarium are just in a big open tank because they need the space to move. All of the other types of stimuli pelagic animals would encounter in deep open water are much more successfully supplemented through enrichment, rather than structures that are built into the design.
Now, horizontal space is just one part of enclosure design - there’s a ton more that goes into designing marine mammal enclosures.The Alliance of Marine Mammal Parks and Aquariums has some pretty intense standards for the exhibits at their member facilities (they appear to me to be much more stringent than even AZA accreditation standards), including things like minimum depth and surface area requirements. Here’s a snippet from their general habitat standards that gives you an idea of what goes into it:
“Space is one aspect of successfully managing an animal collection. It has historically been usedas the surrogate measure of the quality of an animal enclosure. However, quantitative spatialdimensions alone do not adequately describe overall quality of an enclosure nor always directlycorrelate with animal welfare. Variations in enclosure depth can be an important aspect ofenclosure quality for some species while surface area may be for another. Environmental design ismultifaceted, incorporating, but not limited to, depth, shape, sightlines, substrate, interconnectivity,water quality parameters and more. These designs, in tandem with animal management practices,lend to overall animal welfare that is tailored to the species, sex/age composition, and socialdynamics of the animals in the enclosure.”
When you’re seeing very “bare” or “boxy” marine mammal exhibits these days, you’re probably looking at older designs (or show pools, more on that later). It’s much harder to renovate or even just modify big aquatic habitats - not that it’s not possible, but the logistics are much more complicated, and it tends to require prolonged animal moves to other facilities. Terrestrial animals can be put in another yard during renovation, but if you have to drain an entire pool system for a prolonged time, marine mammals generally have to have somewhere else to go. This requires finding another facility which has the space, staff, appropriate specialists, and compatible social groupings of similar species to take the animals. Maintenance is done on multiple-space exhibits by draining one section at a time, or moving the animals to a medical / alternate pool at the same facility temporarily, but that’s not a feasible solution for large-scale renovations given the time it takes for construction to occur, for built rockwork and exhibit features to dry or cure, and to make sure that there are no issues with the construction once it’s exposed to water (not even counting how long it takes for big pools to drain and dry completely in the first place) - and all that has to happen before the animals can be allowed back into the space.
Here’s an example of one of the oldest exhibits I know of that’s still housing bottlenose dolphins: the Top Deck at the Miami Seaquarium. It was built in the 60′s, and it’s a deep cylinder with minimal internal features. (I can’t find an underwater viewing photo for it).
Now, likely part of why this exhibit is so deep and empty is because it was designed to be used for shows. If animals are doing high energy behaviors, rock-work gets in the way and becomes a safety hazard. (If you have people in the water, that’s doubly true - it’s really hard to gauge distance to obstacles when you have your eyes open underwater without goggles.)
One of the things that the cetacean management world has learned since this exhibit was built, too, is that most species of dolphins have very different space needs. This is where the AMMPA provisions for tailoring exhibits to species-specific needs come into play. Bottlenose dolphins do tend to spend more time around reef systems than some of the more totally pelagic species, and so more recent exhibits have incorporated aspects of those ecosystems into their habitat design. Here’s some photos of Discovery Cove at SeaWorld Orlando, which was built in the mid 1970′s- you can see how much the design has changed from the barren deep round pool design characteristic of earlier dolphinariums.
It’s much shallower, but has lots of varied depth areas, rock-work, waves, a beach, and multiple interaction areas (both trainer stations and points where public interactions are proctored). It actually used to have even more features, but things had to be taken out because they were falling apart or being destroyed.
Which brings us to the next topic: anything in a marine mammal exhibit has to be not only animal-proof, but able to stand up to prolonged immersion in saltwater. That actually severely limits what types of things can be permanent fixtures in marine mammal exhibits, and is part of the reason so much removable enrichment is utilized in those situations. You can leave a ball in with a tiger until the tiger destroys it, or a platform until it eventually starts to rot - but immerse those same objects in saltwater constantly and they’re going to start falling apart a lot more quickly.
You know how cetaceans have a reputation for being the jerks of the ocean, because they chew on pufferfish to get high and try to sex up everything? They’re equally inventive in human care, and it’s not just cetaceans that challenge their keepers with their destructive tendencies. Sea lions, walrus, even manatees - they’ll totally mess with and eventually destroy anything that’s not 100% animal-proofed. If there’s something that isn’t screwed down or tied on as tightly as humanly possible in a marine mammal exhibit, congratulations, there is now a new enrichment item for the animals.
TL;DR: Tanks look empty because pelagic animals often spend a lot of time in open water, exhibit design has changed a lot over the years, remodels / renovations are expensive and logistically complicated, and because it’s often easier to utilize enrichment that can be removed / cleaned / repaired than to install permanent fixtures that require a lot of in-situ maintenance.
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