Table 1.

Cercarial behavioural categories.

Unattached behaviours
1	Straight-line- fast tail movements resulting in a linear progressive motion. Movement is tail first with the body following precisely in the direction of motion and tail undulating. Random changes in the direction of the motion occur without pause.
2	Zig- zag line- fast tail movements resulting in a linear progressive motion with constant changes in direction creating a zigzag pattern. Movement is tail first with the position of the body and tail undulating perpendicularly to the direction of motion. Random changes in the direction of motion occur without pause.
3	Circular line- fast tail movements resulting in a progressive motion. Movement is tail first with the body following precisely in the direction of motion. The progressive motion results in movement in a definite circle of measurable diameter with no random direction changes.
4	Spin- body and tail spin around the central axis of the cercaria whilst unattached. There is no linear movement
5	Corkscrew- body and tail spin around the central axis of the cercaria whilst unattached resulting in a linear progressive motion. The manner of spinning can be described as a 'corkscrew' due to the pattern formed by the forward motion. Random changes in the direction of motion occur without pause.
6	Drift- there is no motion of cercaria lasting for more than a brief second, where the cercaria appears to drift unattached.
4/6	Drifting with intermittent spins- there is no motion of cercaria lasting for more than a brief second, where the cercaria appears to drift unattached. This is interrupted by spins where the body and tail rotate around the central axis of the cercaria resulting in a tight spin whilst unattached. There is no linear movement
1/6	Drifting with intermittent forward motion- there is no motion of cercaria lasting for more than a brief second, where the cercaria appears to drift unattached. This is interrupted by fast tail movements resulting in a linear progressive motion. Movement is tail first with the body following precisely in the direction of motion and tail undulating. Random changes in the direction of the motion occur without pause.
7	Body first- progressive motion using the body first with the tail following in the direction of motion. Random changes in direction which occur without pause.
Attached behaviours
A	Attached, but no motion
T	Slow tail movements from side to side or curling with body as point of attachment
T	Fast tail movements with body as point of attachment
h	Slow body movements with tail as point of attachment
H	Fast body movements with tail as point of attachment
b	Slow central body movements with the head of body and tail as a point of attachment
B	Fast central body movements with the head of body and tail as a point of attachment