Behind the Scenes: Going Underwater
Don your snorkel, zip up that wetsuit and tighten those flippers as we dive behind the scenes to meet the awesome aquatic animals coming to Planet Zoo 2!
Hayo Zookeepers!
We're back with more behind the scenes details about Planet Zoo 2, this time peering into the depths to meet the inhabitants of the sequel's brand new aquariums.
So, don your snorkel, zip up that wetsuit and tighten those flippers as we dive behind the scenes to meet the awesome aquatic animals coming to Planet Zoo 2!
Community fishlists
One of the most frequently requested features from across the Planet Zoo community has been the addition of fully aquatic animals.
While fish, turtles and marine mammals frequently topped wishlists across the community, it wasn't until work started on Planet Zoo 2 that we felt we could do these animals justice. Aquatic animals require a wholly different kind of care to their terrestrial counterparts alongside habitats which are a touch wetter, requiring new systems and the technology to support them - all of which we needed to build from the ground up!
The differences for aquatic animals even extended to our research and how we selected the species to feature in the game. As covered in our previous behind the scenes, we do a substantial amount of research for every animal that appears in Planet Zoo 2, from speaking to experts and consulting the IUCN Red List to creating extensive catalogues of reference photos and video.
A wrinkle in this process for aquatics was simply that the data for fish and other aquatic animals can be substantially different compared to terrestrial animals, with population numbers for example often coming from the fishing industry. Simply put, the ocean is still such an alien environment for humans that effective studies can be a real challenge!
When selecting our aquatic species we also felt it was essential that we reflect trends in real world husbandry and ethical practices. Conservation and animal welfare is at the heart of Planet Zoo 2's ethos, which is a key consideration for us with our aquatic species. We want to ensure that the species we include are suitable for the habitats available to design when the game launches.
Once we had completed our research and selected the aquatic animals to feature in Planet Zoo 2, it's time to tackle the process of bringing them to life!
Testing the waters
Of course one of the biggest differences for aquatic animals compared to terrestrial animals in Planet Zoo 2 is their home, the aquariums.
Within aquariums animals spend all of their time moving entirely in a three-dimensional space and interact with player-built structures in a different way than our terrestrial animals, requiring a different approach for almost all interactions.
Everything from movement to social interaction needed to be reworked to accommodate this three-dimensional navigation. Due to the fact that most aquatic animals always remain in motion underwater in some capacity, this required a lot of iteration to get looking right!
Most aquatic animals in Planet Zoo 2 have varying preferences as to where in the water column (the relative height of the water) they prefer to spend time. While we can control their time spent doing behaviours at the surface, on the ground or on the aquarium floor, we needed to add new parameters for epipelagic or mesopelagic animals to set their preferred depths, albeit abstracted to make sense for the game (we don't expect players to build >200m deep aquariums!). This means that you'll see aquatic animals express preferences for where they move in the water, for example a blacktip reef shark will generally prefer swimming closer to the surface than a great hammerhead might.
The seafloor was also an entirely new navigation area for our aquatic animals, so we had to identify new ways to align animals with the ground and underwater objects (rocks, coral, plants, enrichments etc.) to keep their movement natural.
Implementing our aquatic animals led us to ask some unexpected questions like "what exactly does a fish do when it rests?".
Initially, our underwater behaviours didn't support animals just stopping, but when night fell and our humphead wrasse kept swimming round and round we quickly realised, hey, shouldn't these guys chill a bit? Fish may not traditionally sleep like we do, but they do enter periods of rest and less activity which we needed to represent in the game. To support this we created a new hover state for aquatic animals, in which the animal slowly drifts around with little to no propulsive movement. Other aquatic animals tend to sleep on the seafloor, which was incorporated into our new seafloor navigation system.
All these new behaviours and interactions required a great deal of testing and iteration to finally reach the authentic movement and behaviour you can see on your screens in Planet Zoo 2.
Just keep swimming
Another significant difference we had to account for in our aquatic animals was their behaviour in groups. When massed together fish can exhibit spectacularly ornate and complex synchronised movements, presenting significant challenges for us to manage both in terms of game performance and complexity for players.
This led to the creation of shoals for some aquatic species in Planet Zoo 2, which are animals managed as a group entity instead of as individuals, staying together as a single shoal.
Rather than managing each of the hundreds of individual animals that are present in a shoal, both players and the game engine manage the shoal as a unified entity. This even extends to the welfare of the shoal, which is viewed as a group rather than the welfare of each individual animal.
By grouping animals into a shoal, we also needed to build a new navigation system based around "boid" behaviours which controls the direction, cohesion and separation of the shoal as a whole. This enables the animals to move as a unified entity, while still expressing that the shoal is made from a collection of individuals.
Shoals don't have as many different animated behaviours as our other animals, but will change their "shoaling parameters" according to the situations they encounter. For example, a shoal encountering a predatory animal may swarm more tightly and move faster for a while after the encounter than they would normally. Shoals will also react to the presence of larger aquatic animals and even staff divers by swimming out of their way.
There's always a bigger fish
In addition to shoals, Planet Zoo 2 also features more complex individual aquatic animals.
Unlike shoals, these complex animals require more dedicated and direct management as individuals, with their welfare and behaviour reflecting the same level of complexity as our terrestrial animals.
Of course, they also come with their very own quirks that we had to account for!
Many of the more active aquatic animals (specifically obligate ram ventilators like the blacktip reef shark, which need to swim to breathe) would look quite erratic when we first got them to swim around our early aquariums, randomly moving between points within the water body. We discovered that real shark tanks are normally built in a certain way to support their need for long, straight paths without tight turns (such as dumbbell shaped tanks), and sharks in aquariums tend to maximise their available space by following the edge of the tank.
To reflect this behaviour, known as window surfing, our coders developed a new method that creates paths along the edges of aquariums, denoting the probability of an animal in motion generating its path along barrier segments, rather than picking a random point in the water body.
In Planet Zoo 2 you will see most of our sharks window surfing quite often, but other complex aquatic animals will also make use of this system to a lesser extent as well. We found it looks great when every once in a while your sunfish takes a leisurely swim right along the viewing area checking out what the guests are doing.
Just like with our terrestrial animals, we also spent a lot of time introducing behaviour to our animals to make each species feel truly unique.
One behaviour that was discussed a lot within the team was the "puffing up" response of the pufferfish.
Generally, this is a behaviour that pufferfish exhibit primarily as a stress response when threatened. However, this is such an iconic behaviour for this animal that we we decided to utilise it as a very rare, standard behaviour!
Marine management
Generally, aquatic animals have the same set of welfare requirements as terrestrial animals with factors including space, stress, nutrition and more affecting their health and happiness.
The key difference for aquatic animals is that they also have a crucial salinity requirement, something that must be configured correctly to keep these animals alive.
To do this, you'll need to place and manage new water filtration network infrastructure around your zoo, configuring and connecting it to your aquariums. You'll also need to mange the water's temperature and cleanliness to keep your aquatic animals in good health.
Underwater feeding was also something that needed a little love and attention for Planet Zoo 2.
For our semi-aquatic animals in the original Planet Zoo, eating food underwater was optional - you could add an underwater feeder, but in its absence keepers would place food on the ground of the terrestrial part of the habitat. Aquariums obviously don't have that option, so we created a new behaviour for staff to generate free-floating feeders to ensure that fully aquatic animals can be fed even if you forget to place a feeding station down for them. Just like our terrestrial animals in Planet Zoo 2 can do with trees and bushes, aquatic animals can also forage from specific aquatic foliage as well.
Where a traditional terrestrial habitat may be built with a focus on well designed, wide areas, the challenge to building good aquariums in Planet Zoo 2 lies in their verticality. It'll be down to you to build aquariums that provide everything your aquatic animals need, while also giving your guests a good view!
Taking the plunge
Aquariums and fully aquatic animals bring a whole new dimension for players to discover in Planet Zoo 2, with a bucketful of new behaviours, management considerations and build options for you to uncover.
It's been a delight to finally deliver this much requested feature to the Planet Zoo series and we're looking forward to seeing some awesome aquariums come launch in October!
Planet Zoo 2 is available to pre-order now on PC, PS5 and Xbox Series X|S. Join the conversation and keep in touch by following our social channels, subscribing to our mailing list (for an exclusive in-game reward) and watching closely for updates on the website.
