On a world near the sun live two brothers called Vrooms
Who, strangely enough, are built sort of like brooms
And they're stuck all alone up there high in the blue
And so, to kill time, just for something to do
Each one of these fellows takes turn with the other
In sweeping the dust off his world with his brother.
(On Beyond Zebra)
It is conclusive proof of evolution that this planet should apparently just have the one ecological niche, which occupied by species so well adapted in a synergistic relationship. The existence of only one brother would show poor adaption to the environment, since the two brothers have a mutual parasitic dependency on one another which allows them to exercise their designoid function.
(Behavioural adaptation)
Two Biffer-Baum Birds are now building their nest.
They do it each night. And quite often I wonder
How they do this big job without making a blunder.
But that is their problem.
Not yours. And not mine.
The point is: They're going to bed.
And that's fine.
(Dr Seuss's Sleep Book)
As always, the evolution of behaviour represents a challenge to the darwinian model. Dr Seuss shows little tolerance towards the expression of doubt in this area - he has no doubt that there is an evolutionary explanation, even if we don't know what it is.
FLOOB is for Floob-Boober-Bab-Boober-Bubs
Who bounce in the water like blubbery tubs,
They're no good to eat.
You can't cook 'em like steaks.
But they're handy in crossing small oceans and lakes
(On Beyond Zebra)
Floob-Boober-Bab-Boober-Bubs have evidently developed an evolutionary strategy that reduces predation, by virtue of the fact that they aren't palatable. However, their utility as a means for other species to cross small oceans and lakes has ensured their continued presence in the ecosphere despite the lack of obvious role within the food chain.