Hesselberg, Thomas., & Julian F.V. Vincent. 2006. The function of parapodial setae in a nereidid polychaete moving on two different substrata. Journal of Experimental Marine Biology and Ecology 335: 235-244.

Nereis diversicolor has anatomical features used to produce a unique mode of undulatory locomotion. The role of parapodia and musculature in this motion is well understood. However, Hesselberg and Vincent found little information on the role of setae: How do parapodial setae influence polychaete locomotion?

Setae are closely bundled hair-like structures that enhance the paddle-like quality of the parapodia increasing the area for thrust and forward movement. The presence or absence of setae would therefore likely affect both walking and swimming behaviours in N. diversicolor.

All individuals were anesthetized with 7.5% MgCl. Half the individuals had their setae ablated (cut away) from the neuropodia (the ventral parapodial lobe). The other individuals were the controls and had their setae left intact. Measurements of amplitude, wavelength, wave speed, and forward speed were taken using a digital high-speed camera and custom computer program. The interaction between substrate and each type of measurement taken was not statistically significant. The only results of note were that the wave speed of ablated individuals was significantly higher than for non-ablated individuals and the ablated individuals moved slower than non-ablated individuals.

The ablated individuals had to increase their effort in order to move, which was evident by their greater wave speed and slower forward speed. This also indicates that setae do increase friction during underwater locomotion. However, the fact that the measurements taken had no statistical interaction with the substrata, suggest that setal function did not depend on the type particular substrate.

(240 words)

Back to Zool 250 Home Page
(posted Jan. 4 2016)