Taken primarily from Kozloff, 1987, 1996 p. 455 (Copyright 1987, 1996, University of Washington Press. Used in this web page by permission of University of Washington Press)
| Jump to: | ||||
| Lower taxonomic level | Main Page | Alphabetic Index | Systematic Index | Glossary |
| 1a | Arms repeatedly dichotomously branched (picture); plates of arms and disk concealed by a thick skin; diameter of disk sometimes exceeding 5 cm; strictly subtidal | Gorgonocephalus eucnemis |
| 1b | Arms not branched; plates of arms and disk usually distinct, although those on the disk may be small or partly obscured by spines; diameter of disk not exceeding 2 cm; intertidal or subtidal | 2 |
| 2a | Plates on upper surface of arms separated from one another by small supplementary plates; coloration usually with some bright red or purplish red, this typically concentrated in streaks or blotches | Ophiopholis aculeata |
| 2b | Plates on upper surface of arms not separated from one another by small supplementary plates; coloration usually not including bright red or purplish red streaks or blotches (in Ophiura leptoctneia, which is strictly subtidal, the aboral surface of the disk may be rose, violet, or red, with a few streaks; some other species are pinkish, but these ae not likely to have prominent markings) | 3 |
| 3a | Aboral surface of disk with conspicuous marginal notches into which the arms are inserted (photo), each notch bordered on both sides by an arm comb | 4 |
| 3b | Aboral surface of disk without marginal notches into which the arms are inserted, and without arm combs | 6 |
| 4a | Oral shields (the largest plates on the oral surface, situated between the bases of the arms) widest on the side nearer the margin of the disk; spines of arm combs at least 5 times as long as wide, with sharp tips; prevailing color of aboral surface of disk rose, violet, or red | Ophiura leptoctenia |
| 4b | Oral shields widest near their middle portions (photo); spines of arm combs usually not more than 3 times as long as wide, with blunt or truncate tips; prevailing color of aboral surface generally some shade of gray, bluish gray, or greenish gray, rarely reddish | 5 |
| 5a | Spines of arm combs contiguous and with truncate tips | Ophiura luetkenii |
| 5b | Spines of arm combs well separated and with bluntly rounded tips | Ophiura sarsi |
| 6a | With 4 oral papillae on both sides of each jaw | 7 |
| 6b | With 3 oral papillae on both sides of each jaw | 8 |
| 7a | Plates on upper surface of arms nearly circular, hardly wider than long, and barely in contact with one another even near the bases of the arms; interbrachial areas of oral surface of disk (the areas between the arm insertions) without scales | Amphioplus strongyloplax |
| 7b | Plates on upper surface of arms nearly triangular (but with truncated corners), decidedly wider than long and in contact with one another at least near the bases of the arms; interbrachial areas of oral surface of disk with small scales | Amphioplus macraspis |
| 8a | Oral papillae of the pair farthest from the tip of the jaw decidedly longer and wider than those of the other 2 pairs | 9 |
| 8b | All 3 pairs of oral papillae about the same size | 10 |
| 9a | Length of arms not over 4.5 times the diameter of the disk; longest arm spines usually shorter than the width of the arm units from which they originate; ovoviviparous (the young develop in the bursal pockets) | Amphipholis squamata |
| 9b | Length of arms 7 or 8 times the diameter of the disk; longest arm spines longer than the width of the arm units from which they originate; oviparous (discharging eggs instead of brooding young in the bursal pockets) | Amphipholis pugetana |
| 10a | Arm spines blunt, markedly flattened | Amphiodia occidentalis |
| 10b | Arm spines pointed, either not flattened or only slightly flattened (oval in cross-section) | 11 |
| 11a | Arm spines not at all flattened (circular in cross-section) | Amphiodia urtica |
| 11b | Arm spines slightly flattened (oval in cross-section) | Ampiodia periercta |
Amphiodia urtica
Gorgonocephalus eucnemis
Ophiopholis aculeata
Ophiopteris papillosa
(not in key)
Ophiura luetkenii
