Physeter macrocephalus (sperm whale) is being sequenced as an aquatic model organism for the study of respiratory disease, metal toxicity and cancer. Whales are known to accumulate high levels of metals such as chromium, a human lung carcinogen and contributor to other forms of lung disease. Given that the levels of chromium in whale tissue are sufficient to seriously impair or even kill terrestrial mammals, it is hypothesized that marine mammals have evolved novel repair mechanisms that can protect their DNA from metals like chromium. Hypoxia is a well-known cause of respiratory-related diseases such as sleep apnea, chronic obstructive pulmonary disease and pulmonary emphysema. Marine mammals, however, can dive to great depths for prolonged periods of time and not experience these ill effects of hypoxia. The availability of sperm whale genome resources will allow scientists to investigate the molecular pathways contributing to these adaptations.