Original: Unlike some similar invertebrates , they do not have external cilia , but instead have a number of spines along the body , plus up to seven circles of spines around the headBrusca and Brusca , Invertebrates , pp .
Simplified: Unlike some similar invertebrates , they do not have external cilia , but instead have a number of spines along the body , plus up to seven circles of spines around the headBrusca and Brusca , Invertebrates .