If you are a world builder who needs to ground your life form designs in scientific plausibility, the podcasts at BEKernWrites.com are a good place to start. Each runs about forty minutes long. Subjects such as biomes, metamorphosis, metabolism, and genetic material are covered by an actual professor of biology. The lectures stick pretty close to describing Earth life most of the time while briefly mentioning some of the variations found across the galaxy. It is not wildly speculative.
Nearly all life in the galaxy is descended from the same ancestor through the process of panspermia – and something is trying to kill it. The Sage of Sagittarius by Kenn Brody is a fast read. It is full of scientific details, but without slowing down the action at all. The end is satisfying without being too unrealistic (the “bad guy” is destroyed, but at a heavy cost). Each twist makes sense in the context of the story. The characters are quirky, yet believable, and fairly well developed without getting bogged down in a lot of internal musings – nothing wrong with that, but this book’s focus is on the struggle for survival between species of radically different biology (and physics).
In the course of the story, the characters encounter many alien ecosystems. I liked the mollusk-like beings that sift gold from the sea. I liked the “birds” that planted themselves into the ground and became trees. I liked the centipede-like creatures that kept harems. I loved it.
Concavenator is the creator of Horus, a world connected to Victorian-era Earth via wormhole. It is home to red plants with hearts, tube-jet fish, and large land vertebrates. The animals have a double spine. The dorsal spine runs from the skull along the back, while the ventral spine runs from the chest along the tail. They are connected by ribs. The tail houses the respiratory and sometimes reproductive organs. The land animals have six limbs. Some run on the hind limbs and use the forward limbs for grasping while the middle limbs are vestigial. Others stand on the front limbs while the rear four are used as wings. My favorite is the lazy animal that uses its front limbs to carry its head around while it grazes.