According to the cladogram in figure 18-2 , what two characteristics do crabs and barnacles share that limpets do not ?

oak trees? ? what was listed

the principles and empirical processes of discovery and demonstration considered characteristic of or necessary for scientific investigation, generally involving the observation of phenomena, the formulation of a hypothesis concerning the phenomena, experimentation to test the hypothesis, and development of a conclusion that confirms, rejects, or modifies the hypothesis.