My 6-year-old grandson is fascinated with his DS and the Mario games he can play on it. He adventures in caverns of ice and crystal, clouds, small planets covered in greenery, catacombs, electrified lattices, giant billiard tables, etc., avoiding bad guys, giants, pitfalls, carnivorous plants, exploding balls of pure energy, asteroids and various aliens. All against a pleasant background of carnival-type music. He's also good at identifying Pokemon animals but seems to have outgrown it.
In a way he's a lot like I was in the pre-electronic age, curled up with a good book like Treasure Island, Through the Looking Glass, The Arabian Nights or Bullfinch's Mythology. Moving knights and castles and kings around the chessboard. Marveling at the poetry of Lewis Carrol, Hillaire Belloc and Robert W. Service.
Of course, I could have had all of that taken away from me and been given instead books on science, mathematics and logic. Or maybe flash cards so I could learn the French words for common objects. But it wouldn't have been anywhere near the fun. The kind of fun I used to get from books, my grandson is finding in electronic games and (formerly) Pokemon.
Frankly, I think the average kid will enjoy the Pokemon animals a lot more than a bunch of fucking parasites, no matter how "real" and "scientific" the parasites may be. That kid will have plenty of time to learn about science and math and logic as he grows up, but for chrissake, let him be a fucking kid for the short time of childhood that is allotted to him. Give him a world of challenge and adventure, winning and losing, thinking, planning, discovering, falling into traps, getting out of traps, rescuing the maiden, or even getting killed by the bad guy. Tell him about the parasites later. He can learn all about them then.