Which organism utilizes specialized bristles (setae) and muscular contractions for locomotion?
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Answer: C. Earthworm
Explanation
Earthworms move using circular and longitudinal muscles together with small bristly hair-like structures called setae. The coordinated contraction of these muscles pushes the body forward against anchored setae grips. This specialized locomotory mechanism allows efficient burrowing through subterranean soil substrates. Setae are chitinous bristles protruding from the epidermal segments of many annelid worms. Antagonistic muscle pairs shorten and lengthen coelomic segments during peristaltic movement waves. Soil friction provides the necessary traction for setae to anchor segments during forward propulsion.
Observing earthworm locomotion demonstrates basic principles of hydrostatic skeletal biomechanics. Soil aeration by moving earthworms benefits agricultural crop root systems significantly. Ecological studies examine earthworm distribution patterns based on soil texture and moisture content. Cockroaches utilize jointed legs and thoracic muscles for rapid running rather than setae. Snails glide smoothly across surfaces using a muscular foot lubricated with secreted mucus. Starfish rely on hydraulic water vascular systems and tiny tube feet for marine locomotion.
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