The low surface area ofLatimeriagills has been confirmed for a range of body sizes from 450 gr to 80 kg. This is an indication of an inactive mode of life as has now been observed from submersibles. The gill septa indicate thatLatimeriaand lungfishes share an autapomorphy, presumably secondarily lost in tetrapods, since it is generally accepted that lungfishes and tetrapods are sister groups. The presence of a central venous sinus, arterio‐venous anastomoses and other features of the secondary circulation suggest coelacanths are similar to other fish groups in which such structures are present (i.e., Actinopterygii, Chondrichthyes). The absence of a secondary circulation and existence of a type of lymphatic system suggests that Dipnoi are more closely related to tetrapods than are coelacanths.