I think the hydra lacks the specialized cells for touch and chemical detection. On the other hand earthworms have touch, light, vibration and chemical receptors along the entire body surface. Both of them are invertebrates (those animals without a backbone), they include insects, worms, jelly fish, spiders among other animals.
B. because other units are either too small or too large to work with or <span>C. so they can communicate findings without confusion.
You can't tell me that not right</span>
B. A sunflower in a sunny meadow
Sun, wind, ocean waves, tides and geothermal heat
