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.
<span>When grains move closer together, eliminating spaces between them, _____ has occurred? </span>compacation
<em>A</em><em>n</em><em>s</em><em>w</em><em>e</em><em>r</em><em>:</em>
YY
<em>E</em><em>x</em><em>p</em><em>l</em><em>a</em><em>n</em><em>a</em><em>t</em><em>i</em><em>o</em><em>n</em><em>:</em>
Y-purple while y-white
YY is the genotype of a pure breed purple flowered pea plant
Yy is the genotype of a heterozygous pea plant flower (purple is dominant over white)
yy is the genotype of a white flowered pea plant that is generally called as recessive
