{'fraction_non_alphanumeric': 0.05513196480938416, 'fraction_numerical': 0.03577712609970674, 'mean_word_length': 4.57516339869281, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Ontogeny of the Thermal Limits in the Harbor Seal (Phoca vitulina)

We measured metabolic rates (mL O₂ h⁻¹, converted to kcal d⁻¹), deep body temperatures (°C), and skin temperatures (°C) and calculated whole-animal thermal conductances (mL O₂ g⁻¹ h⁻¹ °C⁻¹) of five 3-yr-old harbor seals (Phoca vitulina concolor) at air temperatures between -20° and 35°C. The mean thermal neutral zone of these seals extended from a lower critical temperature of -12.9° ± 1.6°C (SD) to an upper critical temperature of 28.6° ± 1.7°C. Hyperthermia was observed at an ambient air temperature of 35°C. Mean standard metabolic rate was 1,553.6 ± 168.2 kcal d⁻¹, about 1.2 times the value expected for adult animals of similar body mass (mean mass = 49.2 ± 7.5 kg). Mean deep body temperature increased from 37.5° ± 0.30°C at an ambient temperature of 30°C and reached 39.3° ± 0.33°C at an ambient temperature of 35°C. Skin temperature decreased with decreasing ambient temperature but remained well above ambient temperature. Mean whole-animal thermal conductance decreased from an ambient temperature of 35°C until it reached a minimum value of 0.007 mL O₂ g⁻¹ h⁻¹ °C⁻¹ at -4.0°C; it then increased with a further decrease in ambient temperature. In comparison to the thermal limits of the same seals during their first year of life, the results indicate a broadening of the thermal neutral zone with age: an 11°C decrease in the lower critical temperature and a 3.5°C increase in the upper critical temperature. These findings suggest that warm ambient air temperatures should not pose any particular thermoregulatory problems for larger and older harbor seals, even beyond the limits of their current annual distribution.