Biodiversity of Okheania

Speculative evolution


The world of Okheania is a fabulous environment, largely shaped by gigantic trees, forming an evergreen dense surface with their crowns and a dark, hostile space around the trunks, similar to the Ocean’s depth and simply named “the profundity”. This green “ocean” developed on Earth after the sowing of the megatrees, initially developed in laboratory conditions to cope with the pollution of anthropogenic origin. As such, it forms a unique ecosystem with several well-defined biotopes and a flourishing variety of lifeforms. The dominant organismal group is that of Order Ichthymammalia, descendants of the common mammals that underwent extensive evolution and currently resemble in many ways the fishes that previously lived on Earth. Uniquely, the present ichtymammals evolved in a convergent way to these fishes and many similarities could be established between these new species and the now extinct fishes of the past.

Zonation and common flora and fauna

The whole world of Okheania is defined by the gigantic trees, reaching up to a kilometer in height. It is speculated, however, never proved, that what was before the open ocean still remained as a vast, overly polluted water area, deprived of life. The gigantic trees themselves are not eternal, but the propagation of new ones would be highly troubled by the height of the already grown. This would mean that a newly germinated tree will need to grow enormously before having any access to sunlight and could photosynthesize. The gigantic trees bypassed this obstacle by their unique sort of budding – the coleoptiles proliferate through the trunk of an old tree and feed on its xylem, slowly protruding with its roots toward the ground. Thus, the trunks could get enormously wide and consist of the roots of several separate trees.

Figure 1. Zonation of the tree level in Okheania.

The zonation (Fig. 1) of the tree level is as follows: the photic layer, formed by the 1) epidentric zone, e.g. the tree crowns’ surface and the 2) mesodentric zone, about 30 meters below the surface and aphotic layer, consisting of the 3) bathydentric zone and 4) abyssodentric zone. The photic layer is characterized by an abundance of sunlight in the epidentric zone and still enough sunlight in the mesodentric zone. It is populated by the “true” humans, descendants of the first migration to the surface, who lives in either surface cities above the tree crowns, on solid ground (what previously were the mountains), or in tree houses in the mesodentric zone. The predominant plant lifeforms consist of epiphytic and parasitic plants – that attach to the gigantic trees and absorb water and mineral nutrients either from the surrounding atmosphere or directly from the trees. The flourishing animal life consists of insects, small mammals and birds, as well as the dominating ichtymammals.

The bathydentric zone is characterized by the absence of light, low oxygen content and very high humidity. Here, the epiphytic plants are replaced by fungi. Animal life forms consist of ichtymammals, as well as class Caelicephalopoda, also known as air squids (Fig. 2) and class Caeliscyphozoa, or air jellyfishes (Fig. 2). Both classes evolved from previously exclusively marine animals, adapted to the new conditions. Many of these migrate seasonally or during the nights to the photic zone to feed or propagate. This zone is also inhabited by the “abysmal” humans, a degenerated clade of humanity, who refused to undertake the migration route to the surface. The abyssodentric zone, since now, is largely regarded as deprived of lifeforms, other than microorganisms.

Figure 2. Wildlife in Okheania – a variety of ichtymammals (A, B, I), primates (D), rodents (F), birds (E), air squids (C) and air jellyfishes (H, G). All are roughly represented according to the zonation. Size proportions do not correspond to the actual size.

One of the most pronounced ecological effects of the gigantic trees is the amount of gas and heat emissions they release into the atmosphere. A common result of their metabolism, plants do evaporate water vapors, some other gases and VOC, or volatile organic compounds. The gigantic trees, however, represent enormous biomass with active metabolism and thus, a significant producer of such gasses as well as heat. These emissions highly contribute to the warmer climate, high humidity and air currents, making especially the epidentric zone a unique habitat. Especially the density of the atmosphere greatly increases. The leaves cover is very similar to the ocean surface – organisms could fall (or the equivalent of diving), but they can (and actually do) make use of these emissions and stay on the surface, or, even fly. The latter was successfully used by the ichtymammals in their peculiar evolution.

Evolution of mammals after the gigantic tree outbreak

Obviously, the first change that occurred after the first gigantic trees were planted was the cut of sunlight, reaching the surface of the land. Soon this led to the extinction of smaller plants, followed by the extinction of large herbivores and then predators. The only salvation way was the way up, to the surface of the changing tree ecosystem. The mammalian groups with greater chances were bats, primates and rodents because they could either climb or fly their way up. Except for bats, who, for some reason did not succeed in the newly formed environment and went extinct, currently the photic layer of Okheania is abundant in both rodents and primates (Fig. 2), predominantly small, omnivore species. Many of them developed adaptations for flying or climbing.

Rodents, on their own, also evolved and gave the origin of an entirely new organismal group, with no present analog throughout Earth’s history. The ichtymammals (Fig. 2) look like a strange mix between a fish and a mammal, more like fish, but with fur and without gills. They benefited from the above-mentioned gas emissions and use them to fly, but more or less in a way, similar to the mechanism of fish swimming. Some of them lost their limbs and evolved into large carnivores, closely resembling sharks.


[1] Eric Corbeyran, Alice Picard (2008-2012) Okheania. Edition Dargaud.

Leave a Reply

Your email address will not be published. Required fields are marked *