New research proposes that sea animals might have “evolved the ability to live on land many times,” as a report posted on Science Daily puts it.
This challenges “the perception that this extreme lifestyle shift was likely to have been a rare occurrence in ancient times. New research shows 33 different families of fish have at least one species that demonstrates some terrestrial activity and, in many cases, these behaviors are likely to have evolved independently in the different families.”
This Darwinian optimism might be uncalled for, however:
Moreover, Tiktaalik,once assumed to be the earliest terrestrial creature, has lost its iconic status, as land animals predate it by several million years according to the evolutionary timescale.
Now, evolutionary ecologist Dr Terry Ord, an evolutionary ecologist at the University of New South Wales and a co-author of a new paper published in the journal Evolution, acknowledges that the real threat for sea animals trying to settle on land is drying out:
"The real difficulty in developing a fully-fledged terrestrial lifestyle may be in preventing drying out. This has direct consequences for them breathing on land because they still require their gills, which need to stay moist to function properly."
Mudskippers can jump onto land but if they won’t return to the sea, they will eventually dry out. They are not designed to be terrestrial creatures.