Table 1.

Optical, morphological and physiological properties of the frontal regions of compound eyes in four species of insects: L. leucozonium (L leu: diurnal bee, apposition eyes, n=8), M. genalis (M gen: nocturnal bee, apposition eyes, n=8), O. belial (O bel: diurnal dung beetle, superposition eyes, n=8) and O. aygulus (O ayg: nocturnal dung beetle, superposition eyes, n=8).

symbol	parameter	unit	L leua	M gena	O belb	O aygb
d	distal rhabdom diameter	μm	1.6	8.0	6.5	13
f	focal length	μm	57	97	373	503
A	aperture diameter	μm	20	36	187	613
k	absorption coefficientc	μm−1	0.0067	0.0067	0.0067	0.0067
l	rhabdom length	μm	220	350	32	86
S	optical sensitivity	μm2sr	0.1	4.9	1.3	68
Neq	bumps at equal intensityd	–	13±2	873±93	62±15	3267±980

^aValues for bees were obtained from Greiner et al. (2004).

^bValues for dung beetles were obtained from McIntyre & Caveney (1998).

^cValue for lobster (Bruno et al. 1977).

^dSee §2 for definition.