What are 20?

Answer 1

This is just a suggestion but consider comparing/contrasting a dog, cat, horse, mouse, snake, amoeba, fish and a human for what should provide more than twenty specific adaptations. Then consider why each animal is built that way.

In reality there are multiple adaptations associated with a single characteristic.

Some General Categories (some more specific than others as I am winging it)

teeth (grinding, shearing, hollow....none)

scales (no scales...)

bones (cartilage, no cartilage, entirely cartilage...

hair (hollow, undercoat, long, short...)

legs (no legs, long, short, jointed, 1 toe, 2 toes...)

camouflage (spots, stripes, agouti, dilute...)

gills/lungs

ability to stand upright

hands (opposable thumbs...)

vocal cords

whiskers

beaks

eyes

tails (no tails)

claws (retractable, non retractable, short long, sharp dull)

unicelluar/multicelluar

locomotion (cilia, flagella, water jet, current,

fat as insulation (blubber, fat...oil)

hibernation, estivation, brumation

multiple organ systems

Oh...and a brain...