R. Lagergren et al., INCREASED DRAG, AND THUS LOWER SPEED - A COST FOR MORPHOLOGICAL DEFENSE IN BOSMINA (EUBOSMINA) (CRUSTACEA, CLADOCERA), Functional ecology, 11(4), 1997, pp. 484-488
1. The swimming speed of two forms, an extreme and a typical, within t
he cladoceran subgenus Eubosmina were examined using a three-dimension
al video-technique. The extreme form has a very high carapax and extre
mely long antennule, features probably involved in predator defence. 2
. It was found that the extreme form swam almost 40% slower than the t
ypical form. 3. Calculations show that the extreme form had to work at
least 12% harder to swim at the same speed, or if it used the same am
ount of energy to swim, the extreme form would swim 6% slower. Increas
ed drag, because of its distinguishing carapax and antennule, is thus
the most likely explanation for the slower swimming speed of the extre
me form, assuming it selects the same power output. 4. Swimming speed
can be correlated to food intake either by the frequency of hits to ed
ible food particles or by the time to swim from a poor food patch to a
good one. So the reduced speed is probably a great cost for the extre
me form.