     [ 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

  draw: ->
    super()
    @drawHead()
    @drawTail()
  # some decorations that let us see the animal's angle of vision
  # the direction of its gaze, and where it's headed

  jitter: -> 0
  stationary: -> !( @velocity[0] || @velocity[1] )
  move: ->
  ctx: -> @context ?= @universe.ctx
  draw: -> @drawBody()
  drawBody: -> @drawCircle(
      @x
