Age differences in Behavior
With age and size come differences in the use of aquatic
bipedal behavior in basilisks. The older lizards are more likely to
abandon bipedal behavior and swim through the water instead. In
general, lighter lizards are able to keep a greater portion of their
body out of the water, allowing for more efficient motion across it.
Heavier, and typically older, basilisks can swim through the water
faster than they can run through it. According to Joshua Laerm, "[t]he
ratio of the weight to surface area provided by the feet is probably
the most limiting factor involved in aquatic bipedalism, the
expectation being that very young or small bipedal lizards would be
able to provide greater drag forces propotional to their body weight."
It is more effective for the younger lizards to move bipedally through
water because they can do so more quickly than they can swim. In older
lizards, however, the opposite is true.