Jellyfish life cycle / chicken-egg

Jellyfish life cycle (Scyphozoa)

The life cycle of the Jellyfish is extremely complex and fascinating.

If you think the old chicken-egg problem is a stumbler (it isn't, see below) try to figure out which came first, the scyphistoma, or the strobila, or the ephyra, or the medusa, or the planula :)

Chicken-Egg problem

This has a very complete and elegant answer, just realize there is an equivocation in the use of the word 'egg':

a) An egg that CONTAINS a True Chicken - the egg which contained the first True Chicken would have come from an Almost Chicken; with some mutation marking the difference in the species (probably related to one of the egg-shell related genes). This is the most generally correct answer.

b) An egg FROM a True Chicken - then the chicken must have come first, evolutionary-speaking. This is only true an usual sense of 'Chicken Egg' (in common usage a Chicken Egg would contain a Chicken and thus answer 'a' would apply).

c) Any type of egg at all - eggs in general are much much older than chickens. I don't think this is what anyone means when they pose the question but is included in the interest of completeness.

I go into much more detail in: The Chicken-Egg problem, an evolutionary parable