shark noun ▶ A big shark swam slowly past the glass wall. dolphin noun ▶ The dolphin jumped high above the water. octopus noun ▶ An octopus has eight long arms and changes colour. turtle noun ▶ The old turtle moved very slowly across the sand. jellyfish noun ▶ A pink jellyfish floated quietly in the tank. crab noun ▶ A small crab walked sideways on the rocks. seal noun ▶ The seal clapped its flippers for the children. swim verb ▶ All sea animals swim, but in very different ways.