are they consumed ?
Yes, mainly crabs, lobsters, shrimp, crawfish, and prawns.
Crustacean
Many crustaceans are consumed by humans, and nearly 10,700,000 tons were produced in 2007; the vast majority of this output is of decapod crustaceans: crabs, lobsters, shrimp, crawfish, and prawns. 
where are the walking legs of crustaceans found UNANSWERABLE what are these type of creatures? They comprise of almost 67,000 described species, mostly small and their morphology varies greatly from the largest arthropod in the world – the Japanese spider crab to the smallest the 100-micrometre-long "Stygotantulus stocki". how do they mate? They reproduce sexually as the males decide which females to mate with by dietary differences.
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Crustacean [SEP] Consumption by humans
Many crustaceans are consumed by humans, and nearly 10,700,000 tons were produced in 2007; the vast majority of this output is of decapod crustaceans: crabs, lobsters, shrimp, crawfish, and prawns. Over 60% by weight of all crustaceans caught for consumption are shrimp and prawns, and nearly 80% is produced in Asia, with China alone producing nearly half the world's total. Non-decapod crustaceans are not widely consumed, with only 118,000 tons of krill being caught, despite krill having one of the greatest biomasses on the planet.