Black widows spend their entire lives in their cobwebs, sitting and awaiting predators. When a

prey item stumbles into their web, they rush out quickly to subdue it but tend to fatigue
quickly and cannot maintain high levels of activity for long periods. As a result,
____________________.



a. they have mostly fast-twitch muscles
b. their muscles have high levels of myoglobin
c. they need a constant supply of oxygen for fast contractions
d. actin and myosin function without calcium


A

Biology & Microbiology

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