Pilfering crab has insect's nose -- evolution

[DELUSIONAL]

http://news.bbc.co.uk/1/hi/sci/tech/4206077.stm


A land crab re-invented key features of the insect nose over millions of years - a striking example of convergent evolution, Current Biology reports.

An animal's sense of smell needs to operate under very different conditions in air compared to water.

The crab has achieved this in the same way as the ancestors of insects did.

The robber crab, which is descended from marine crabs, had to develop a new way of smelling things when it moved out of the sea and on to land.

Insects evolved some 438-408 million years ago, from an ancestor that also crawled out of water into an air filled-terrestrial environment.

[mike_c]

1. point of clarification....

Insects did not evolve from an aquatic ancestor except in the same sense that we evolved from something fishlike. Their ancestors were terrestrial arthropods. The point about convergent evolution is interesting but not especially surprising. Both insects and crabs have compound eyes with similar architecture, for example, although no one thinks that's a matter of convergent evolution, but rather of distant relatedness. More to the point, both have antennae studded with chemoreceptors- all that remained to be done was selection for sensitivity to volatile gasses and other chemicals encountered in its new environment. Cool, but not earthshaking.

Finally, and I offer this as someone with a Ph.D. in entomology, insects do not have noses. They have olfactory receptors on various parts of their bodies, including their antennae, but let me repeat, in my best professorial tone, insects do not have noses.

[bryant69]

2. What about Jiminy Cricket?

Didn't he have a nose?

Q. If they don't have noses, how do cockroaches smell?
A. Terrible!

Bryant
Check it out --> http://politicalcomment.blogspot.com

[mike_c]

3. oh, yeah-- I forgot about Jiminy....

[karlrschneider]

5. If you tell a lie, your olfactory receptor will elongate!

Now I need to figure out how to get my pecker to detect aromas. :D
:evilgrin:

[karlrschneider]

4. Just wondering (and probably nitpicking)...how does a "nose" differ in any

meaningful way from an "olfactory receptor"? Couldn't we say that insects have "multiple" noses? Disclaimer: IANAE

:D

[mike_c]

6. glad you asked that....

Nose:




Insect antennal olfactory receptors:




Vertebrate olfactory receptors are in their nasal cavity, tucked up close to their brains. Not in their noses.