Understanding Evolution

Many pairs of limbs

We've seen that arthropods all have bilateral symmetry, segmented bodies, hard exoskeletons and jointed legs. Another character inherited by all arthropods is many pairs of limbs.

Lots of Limbs
The ancestral arthropod had many body segments with one pair of limbs on each segment. All arthropods inherited multiple limbs from that ancestor. However, in many arthropods, some limbs have even been lost completely as they evolved to be smaller and smaller, while others have evolved into new shapes. Crayfish, for example, have limbs specialized for different functions.

ventral view of a crayfish

Try it out!
Which of these animals have many pairs of limbs?


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