Fauna

Fauna is the term for animals, in this case the animals of planet 4546B. Fauna in Subnautica can be found all over the planet, from the deepest darkest depths of the secretive Lost River to the vibrant Safe Shallows, and even to the fiery pits of the Lava Lakes.

Fauna on Planet 4546B comes in all shapes and sizes, ranging from the tiny, cave-dwelling Rockgrub, to the colossal Sea Dragon Leviathan that spews molten minerals from its mouth. Fauna on Planet 4546B are capable of enduring and adapting to various environments, although unable to thrive due to the presence of the Kharaa Bacterium. Certain species of small fauna can sometimes be seen forming shoals. Fauna on 4546B also have yellow blood. The fact that the appearance of some species of the planet being similar to that of Planet Earth species can be explained as a simple case of convergent evolution.

The player can scan Fauna with the Scanner, allowing them to view information about the creatures in their PDA.

Reproduction
All known fauna on Planet 4546B are simultaneous hermaphrodites, meaning that they have a single sex capable of playing the role of either the male or female in reproduction, and every individual being able to lay eggs and fertilize them. Two parents are still required to fertilize the eggs once laid, making it sexual reproduction. At least one fauna species is exempt from this and reproduces entirely asexually although the norm for the planet is sexual reproduction, as can be observed in all species that can be placed in an Alien Containment unit who will require twice individuals of their species to produce eggs. All known species on 4546B reproduce via egg-laying.

Invertebrates make up the minority of fauna species within the crater on Planet 4546B, around 16.5%, contrasting with Earth on which invertebrates make up around 97% of fauna species.

Trivia

 * As of the Dangerous Creatures update, all fauna have yellow blood. Before this update, fauna had red blood. This is due to the ESRB giving Subnautica a higher rating than expected due to red blood.
 * Scientifically speaking, the fauna of planet 4546B might have high concentrations of vanabin in their blood.
 * Fauna were once intended to posses inherent attributes, that would have caused them to exhibit unique behaviors. These included, e.g., "Fertile" (occasionally lay eggs that can be hatched), "Alpha" (attacked the player if other creatures were killed by the player in the immediate vicinity), "Complex" (specimens take longer to scan), "Greater" (specimens are of larger size and weight). This however was scrapped upon the final release.
 * In the very early stages of Subnautica, there was an unused Sandworm that could only be spawned using the console, it would stay in one place under the ground and when the player or an npc was right above it, it would spring up and would do 1 damage but at a very fast rate. It never had any animations, except it shooting out of the ground and back into its hole.
 * There was also an unused Grabcrab that would leave its burrow and search for items to drag back to its hole. Its burrow also had the same model as the Grabcrab.