algal-forager amblyrhynchus-cristatus black color colored colors colour coloured colours crest-of-spines forage forager graceful-swimmer heat-absorption Iguana large lethargic lethargy lizard long-sharp-claws marine-iguana marine-reptile reptile reptilian salt salty sea spikes spiky spiky-dorsal-fin subtidal-algae-forager sun-absorption Sunbather