Venus is similar in size, composition, and, therefore, gravitational force. It's not unlikely at all that in the vastness of the universe, there is another similarly sized planet.
Toxoplasma gondii, the protozoa that causes toxoplasmosis, is known to change the behavior of rats and mice causing them to be drawn to the scent of cats as opposed to fearful of the scent. This results in the mouse being eaten to allow the parasite to sexually reproduce in its host, the cat. There are other similar examples in nature.
And, just to nit-pick, your examples of earth's animals that do not share human's basic body shape is incorrect. Seals have four limbs, bilateral symmetry, and one head. Earlier ancestors of snakes and whales did as well, and vestigial remnants remain in many modern species of these animals.
Toxoplasma gondii, the protozoa that causes toxoplasmosis, is known to change the behavior of rats and mice causing them to be drawn to the scent of cats as opposed to fearful of the scent. This results in the mouse being eaten to allow the parasite to sexually reproduce in its host, the cat. There are other similar examples in nature.
And, just to nit-pick, your examples of earth's animals that do not share human's basic body shape is incorrect. Seals have four limbs, bilateral symmetry, and one head. Earlier ancestors of snakes and whales did as well, and vestigial remnants remain in many modern species of these animals.