Life in Cold Blood

The 'last' or latest (depending on how it is viewed) of David Attenborough's natural history series commenced last night (http://www.bbc.co.uk/pressoffice/pressreleases/stories/2008/01_january/08/cold.shtml) dealing with Linnaeus' 'foul and loathsome' amphibia and reptiles. The programme was actually quite sympathetic to these diverse and interesting animals and emphasised the point that the reptiles in particular are not actually 'cold blooded' (it's just that they don't use very much of their own metabolism to 'power' a high body temperature, generally relying on solar power to fuel much of their vigorous activity). Reptiles are actually on a weight for weight basis more efficient than mammals (certainly in terms of the food that they require). This was very nicely illustrated using thermal camera images to assess the diving activities of the Marine iguanas of the Galapagos that have to heat up by basking on the rocks before they can dive under a cold sea (for a very finite time) to browse on seaweed. New pieces of information (for me at least) was the filming of a frog that also basks and produces its own 'sun cream' that it assiduously spreads on its body and the revelation that the Leather-back turtle is the only living reptile that has the equivalent of blubber (enabling it to deal with cold seas). I found the speculation about the possible temperature regulatory abilities of dinosaurs (with cherry pickers and a starting bone from a T. rex) a bit 'gimmicky'. The giant boa consuming a deer head first was a bit predictable but still very graphic. The tiny pygmy chameleon of Madagascar was impressively small. Much was made in the programme about the 'emotional warmth' of these animals illustrated by flashing of neck skin in Anolis lizards, fighting in tortoises, horned chameleons and Strawberry frogs, 'tasteful' mating in Saltwater crocodiles and Painted terrapins, brood defence in salamanders and parental care in Spectacled caimen. Some of this involves a certain degree of anthropomorphism. The programme dealt well with the impact of environmental temperature on sex determination in many reptile species and the abilities of some reptiles to hibernate even when ice crystals form in their bodies. It may come up later but I think it was a pity (given many of the examples used in the programme) that more wasn't made about the characteristics of reptiles (energy efficiency, egg laying habit, ability to hibernate and to modify sex on the basis of environmental temperature) probably facilitating their abilities to become early colonisers of remote Oceanic islands. They often arrived well in advance of mammals who often required human agencies to transport them. I await the continuation with interest.