Eosapien
The Eosapiens are the most advanced life on Darwin IV. They have about the same level of intelligence as early humans, such as Homo erectus. Eosapiens float through the air by way of two methane sacs. They live in small tribes, can manipulate objects such as spears and clubs, and hunt the other creatures of the planet. They hunt Skewers, and are hunted by them
The main difference between the Eosapiens in Expedition and the ones in Alien Planet is the fact that in the book, the Eosapiens are 30 meters tall. On Alien Planet, they are roughly 9 meters long.
Although these creatures differ somewhat between the Eosapiens in Expedition and their counterpart in the TV special, they both appear to be rather intelligent and interestingly powerful. In the book, they were depicted as being able to use their spears and clubs to make a cage to carry their game away. They are also extremely social, being able to communicate via the light patterns on their heads and (as shown on the special) can run simple mathematics.
A basic language and culture seems evident through the peculiar markings they leave near major landmarks such as the ocean. Even though they are peaceful towards their own kind and the probes as well as anything that might show intelligence, they grow aggressive when camera discs are thrown into the air. However, this may just be a misunderstanding, as they may be seeing the discs as weapons.