Q. What are the major features of fishes associated to the habitat where they live?
Fishes are all aquatic animals and thus they have a hydrodynamic elongated body appropriate to move under water, with fins and without limbs that the habitat conditions the branchial respiration too.
Q. Comparing to cyclostomes (primitive vertebrates) what are the major novelties presented by fishes?
Compared to cyclostomes, evolutionary novelties presented by fishes are: pelvic and pectoral fins, paired and symmetric the presence of mandibles.