The descendants of the leopard seal, Hydrurga leptonyx, have changed little from their ancestral species. The lion seal is still major predator of the ocean. When young, the lion seal lives as a filter feeder in open ocean; when it reaches maturity it returns to the coast to act as a top predator and breed.

The abyssalephant shares many traits with its ancestor, the southern elephant seal Mirounga leonina. However, with the influx of pelagic and benthic life triggered by the larger land area of the Magallanic islands, it has grown even larger. The abyssalephant feeds on squid and fish, many of which it hunts by their bioluminescence. Its size has had one major detrimental effect on the species. The abyssalephant is too large to fully come onto land as an adult. Note that the restricting factor in abyssalephant terrestriality is locomotion rather than environmental survival. Earth elephant seals are actually one of the few seals that can and will remain on land for indeterminate periods of time and abyssalephants are similar. The female will either give birth in shallow coastal water or move close to the beach during high tide and allow the tide to go out, leaving the individual on land to give birth. When the tide returns, the abyssalephant can leave. While young abyssalephants face many predators, perhaps one of the driving factors to the move to water, only one organism is willing to attack adults. When an abyssalephant very shallow water or on land, especially when birthing, heidangels will land on the upper back, close to the neck. The abyssalephant is unable to move well or attack, rendering it relatively defenseless, though more often than not heidangel attacks are not lethal for full grown adults.

While many of Tsalal's terrestrial hypercarnivorous niches were filled by petrels and sheathbills, mammals did manage to gain a small foothold in the inland. The Antarctic fur seal (Arctocephalus gazella) on our Earth is a major temporary inhabitant of the Kerguelens. On Gigas, it gave rise to a lineage of fully terrestrial scavengers and hunters. However, this wasn't an easy path for the animals. During the southern winter, Antarctic fur seals would migrate to the Antarctic ice shelf, though the behavior doesn't seem to be well understood on our Earth. On Gigas, seals attempting to do this would have likely died, and in large numbers. However, populations did learn to remain on and around Tsalal. While the gullet seal has remained in the ocean and become a even more-specialized krill eater, other species have arisen to take advantage of the new land.

It would be a mistake to see the species name of the Antarctic fur seal and assume that the were already adept at traveling by land; gazella refers to the SMS Gazelle which first collected its specimens. This is not to say that the fur seal did not already have adaptions predispositioning it for a more terrestrial life. As a fur seal, they are more capable of moving on land than true seals, being able to support their body weight on their limps rather than drag their body along behind them. However, like all southern fur seals and unlike sea lions, the Antarctic fur seal is incapable of moving its rear limbs independently during locomotion. The Antarctic fur seal, however, has still been clocked as moving up to 20km/h on land in short bursts, significantly greater than a human jogging, though slower than the average sprint. Even as the Artcocephalenes adapted to life on land, they were unable to lose the biomechnical restriction on their hind limbs, leading to their namesake bounding gate, though they are able to reach and maintain greater speeds. Also note that Acrtocephalus ancestrally bred on land, unlike many sea lions, further predispositioning them to make such a transition. The impetus for this transition to total terrestriality may have been facilitated in part by Gigas placing parts of common breeding grounds much farther from the water.

All of the bounding seals are of a smaller average size than their ancestor, the pup weasels especially so. This decrease in size was partially a result of some neotenization, causing the seals to resemble young fur seals in some respects including limp proportion. Regardless, the limbs of bounding seals are less flipperlike than those of their ancestors. The seals also appear to be much less sexually dimorphic, with males being much closer to females in size. One surveyor has suggested  that the raptor seal and bush pup weasel are the juvenile and adult forms of the same species. Unfortunately, only limited resources are available for biological surveys, but the general consensus does not support this, and the following summaries are written as if this was not the case. On our planet, sporadic bushes of Azorella selago dot the Kerguelen landscape. However, in much of Tsalal's lowlands, the descendants of Azorella form a solid covering of the ground. It turns out that factor preventing the plant from doing the same on Earth is a lack of water. On Grande Terre, though the lowlands are dotted with lakes, much is still rocky and dry. Counterintuitively, the increase in land also led to increased precipitation, transforming dry plains into soupy marshland, most notably in what would be the Courbet Peninsula on our Earth. The Azorella relative was able to out-compete other plants, though occasionally Lyallia descendants will peak their way through. The semiporous plant life, to thick for the flightless spurwings to navigate well, shield the nests of a variety of avian wildlife, as well as containing some of Tsalal's largest insects. Both are sources of food for the pup weasel.

At a size comparable to that of a raccoon, the pup weasel is a danger only to small, relatively defenseless animals. The seal is willing eat bird eggs and young when available, as well as grubs and adult insects. The pup weasel will also eat roots and young stems and leaves if necessary, but retains a primarily carnivorous diet. Though the pup weasel isn't typically aggressive towards larger animals, it will use its bite against defensive parent birds or other pup weasels when competing for mates.

The western pup weasel is a closely related species found in and nearby most of the streams and lakes of Tsalal. The most acquatic of the bounding seals, it mostly consumes freshwater fish. Not all of the flat, hospitable land of Tsalal is covered in Azorella. The largest hadruck, the foie gras plays an instrumental role in some regions by clearing heavy plant growth, allowing plants such as descendants of Cook's tussock-grass and the Kerguelen cabbage to flourish. In these grasslands, the raptor seal can hunt its prey. Its larger, galloping gate allows it to snatch juveniles hadrucks, smaller spurwings, and other birds when it available. The raptor seal is grows to up to approximately 1.3 meters in length. Not able to run for long periods of time, it has to pay close attention to surroundings when hunting, as hadruck parents can attempt to drive it off, while larger spurwings will also occasionally steal prey  from it or even make the seal prey itself.