Table 1 Distribution of eyes in Onychophora and Chelicerata[1, 5, 16, 22, 37]
Median eyes | Lateral eyes | |
|---|---|---|
Onychophora | One pair of eyes (median/lateral affinity unknown) | |
Pycnogonida | Four | Absent |
Xiphosura | One pair, plus one fused median rudimentary eye | One pair of lateral compound eyes, plus one pair of lateral rudimentary eyes |
Scorpiones | One pair | Three to five pairs, plus one pair of nymphal eyes |
Araneae | One pair (= principal eyes or anterior median eyes) | Three pairs (= secondary eyes) |