     [ start, end ] = if left then [ @angle, @angle + Math.PI ] else [ @angle - Math.PI, @angle ]
     [ x, y ] = @edgePoint point, rad + @radius
     @drawArc x, y, rad, @bodyColor, start, end
+  calcTailSize: ->
+    size = @radius * @maxAcceleration() / @genes.maxAcceleration[2](@)
+    Math.max 2, size
   calcEarSize: ->
     ratio = @auditoryRange() / @genes.auditoryRange[2]
     size = ratio * @radius / 3

  jitter: -> 0
  stationary: -> !( @velocity[0] || @velocity[1] )
  move: ->
  draw: -> @drawBody()
  drawBody: -> @drawCircle(
      @x

  drawCircle: ( x, y, radius, color ) -> @drawArc x, y, radius, color, 0, tau
  drawArc: ( x, y, radius, color, start, end ) ->
    return unless radius > 0
    ctx = @ctx()
    ctx.beginPath()
    ctx.arc x, y, radius, start, end
    ctx.fillStyle = color
