Oolon Colluphid

<sharp intake of breath> Nor according to the course book either! (Check the pages with box of phyla descriptions, something like page 20 iirc: Brachiopoda, Cambrian to Present! :Cheeky: )
Not very, so a good one. Jet Black was looking into it recently, and iirc termites are a sort of cockroach (in the same way that a rhino is a sort of horse ).
I think so. Was just looking up keratin for an S182 question, and arthropod silks are a sort of keratin... but "it is unclear whether they are phylogenetically related to vertebrate keratins" (Wikipedia).

MrDarwin

I find it hard to believe that silk comes from a common ancestor. Within insects, and within arachnids, maybe although it's found in several lineages that seem only distantly related. But since arachnids and insects seem to have conquered the land independently, and I don't think silk is known in any aquatic lineages of arthropods (secondarily aquatic insect larvae aside) I suspect that silk has had at least two completely separate origins. (Although it silk be like eyes: although the details of complex eyes have apparently evolved independently in numerous lineages, the basic genetic underpinnings seem to be homologous and inherited from a common ancestor that may have had nothing more than light-sensitive spots.)

Berthold

Air-breathing fish:

*The primitive way (lungfish)

*Through the gut (Cobitidae)

*Through a special organ in the gill space (Anabatidae)

*Another of this kind, independently evolved (certain catfish, e. g. Channallabes)

*Through nothing special (Periophthalmus)

Malintent

All very interesting stuff.... But how does any of this support evolution any more than "God must like diversity in animals" support Intelligent Design?

Codec

It doesn't per-se, anything can be done through supernatural means - even the stupid. However I think you'd expect a designed solution to reuse an existing solution where possible. You need a windscreen wiper on a car and an aeroplane, you'd probably use the same technological solution, rather than starting from basics each time.

Magnus Armstrong

And you would expect that an evolutionary track to produce many different answers to the same problem, right?

RBH

No, one would expect multiple evolutionary 'tracks' to produce different 'answers' to the same problem. See here for an example of how the same initial conditions, with the evolutionary process differing only in the random mutations that occur, give rise to different structural 'answers' to the same functional 'problem'.

RBH

Dina Noun

Just as a thought, what about our immune system that Behe thinks is IC and therefore designed? Back in the 1300's almost 1/3 of the entire European population was wiped out by the bubonic (and pneumonic?) plagues. Is Behe's God ... I'm sorry, designer ... such a poor designer that He couldn't design a system that could work against all comers, or did Behe's God ... I'm sorry, designer ... create a 'bug' that was able to overcome His other design ... our immune system?

Berthold

Extreme male dwarfism and dependence on the female in Ceratias holboelli (a fish) and Bonellia (a worm).

Alternation of generations in cnidarians, tunicates (salpes, in which the poet/naturalist Adalbert von Chamisso discovered the phenomenon), aphids and daphnias.

The gonopodium of the male Poeciliidae, functionally a penis, is an altered ventral fin.

Dlx2

Every once in a while, designers like to try the whole sail-back thing.

It's been done in slightly different ways in a variety of tetrapod taxa, including but probably not limited to:

Edaphosaurids (Edaphosaurus, Ianthosaurus)
Sphenacodontines (Ctenospondylus, Dimetrodon)
Dissorophid temnospondyls (Platyhystrix)
Crurotarsan archosaurs (Ctenospondylus, Arizonasaurus)
Spinosaurid therapods (Suchomimus, Spinosaurus)
Allosaurid therapods (Acrocanthosaurus)
Sauropods (Amargasaurus)
Hadrosaurine ornithopods (Ouranosaurus)