MrDarwin

Or two, depending on whether you consider Hemiptera and Homoptera to be two orders or combine them into one

Oolon Colluphid

Well, I finally got to check my insect book (Chinery, Freeman, Oldroyd et al, 1979, Insects: An illustrated survey of the most successful animals on earth). On mayflies, it says:
Which makes sense, as far as it goes, but still doesn’t explain why they can’t do it the way of other aquatic insects! All the rest get out of the water okay, and to do it the mayfly way wastes a whole exoskeleton.

The problem with ‘my’ list -- currently at the printed-off and proofreading stage -- is that I keep turning up more items! There’s those dolphin embryo hindlimb buds, and I’ve been debating with myself as to whether there’s something ludicrous about echidnas (apart from the reduced poison spur).

Apparently, echidnas can curl up when laying their eggs (which are very small), and so in effect lay the egg straight into the pouch. Fine. But why not lay it there from an inside opening, as I suggested for marsupials? And then, why does it need a shell? Shells are for holding things together while outside the body.

But I’ve not convinced myself it’s a really stupid design.

Conversely, one might think that if a pouch is a Good Idea™ for an egg-laying thing, that it would save birds having to fanny around with nests. Ah, you’ll say, but birds have to fly, and having a nestfull of infants in a pouch would make flight difficult. Sure... but not for flightless birds! If a kangaroo pouch is so great a design, why don’t ostriches have it?!

But like I say, I’ve not convinced myself. Can anyone else suggest why these things are good design really? Or more flaws with these designs?

Cheers, Oolon

Oolon Colluphid

Just to say, thanks for all the help, guys! :notworthy

I'll let you know when I get some usable pics.

Cheers, Oolon