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Whenever there is a documentary about animals and you get to the colder regions, you will hear about Seals and their layer of blubber keeping them warm.
But the skin is on top of the blubber, in direct contact with the cold water (and air). Do they feel the cold outside the way a human would?
Humans (and other animals) do not feel temperature; when we “feel cold” we actually sense that our body starts to lose heat (we feel the heat transfer). Pinnipeds, notably phocid seals (True seals or earless seals), restrict heat transfer to the environment by reducing skin temperature. To do so, phocids have a thick layer of subcutaneous blubber (or hypodermal adipose tissue) with a low thermal conductivity, which significantly reduces heat transfer via conduction (insulating the skin surface from the body core). On contrary, flippers are the areas of the body with little blubber. Interestingly, in phocids, flipper skin tends to be the least emissive region during cold weather (Kharmas et al. 2012), which could be explained by the presence of counter-current heat exchangers (found in the flippers of pinnipeds). Counter-current heat exchangers (another thermoregulatory strategy) are present in peripheral body parts and help retain heat in the core body by rewarming cold venous blood returning from the periphery as it passes in proximity to outgoing, warm arterial blood. To summary, phocids limit heat transfer with a blubber layer and control heat transfer by using blood flow (see Favilla and Costa, 2020 for a review about Thermoregulatory adaptations in marine mammals).
