[blakestyger]

The other day an insect landed near me during a meeting. What struck me was the extreme thinness of its legs  - almost hair-like.

The question is: how does liquid flow in the minute vessels in these tiny body parts. Wouldn't the viscosity (especially in the cold-blooded) of any fluid make them harder to pump?

Clearly, these problems have been overcome - but how?  []

[RD]

flies have extra (accessory) hearts ...

As muscles contract to move the wings, blood is squeezed around the muscles into different body areas. Sloshing works for the main body cavity, but can’t get blood into thin appendages, e.g., legs, antennae, and wings. At the base of each appendage there is an accessory heart – another small muscular pump – that moves blood through the appendage to provide muscles and nerve cells there with nutrients dissolved in the blood.

http://www.ccmr.cornell.edu/education/ask/index.html?quid=1091

[Must have been a facinating meeting  [] ]

[blakestyger]

Thank you RD, that is most useful.

I posted this question to Madscientists after there was no response here and they did reply but your link contained more detail.