Figure 1.
Discovery rate of ophiuroid species since 1758.
Figure 2.
A. Ophiolepis superba, a typical five-armed form with simple arms; B. Ophiacantha enopla veterna, a form with long serrated arm spines and spinelets covering the disc; C, Ophiactis tyleri, a six-armed fissiparous form; D. Euryale aspera, a basket star with branched arms. Scale bars in millimetres.
Figure 3.
Skeletal morphology of brittle stars shown on Amphiura chiajei.
SEM images. A. dorsal disc and arms; B. arm dorsolaterally; C. isolated lateral arm plate with spine articulations; D, E. arm vertebrae dissected from the inside of the arm; D. distal face; E. proximal face; F. ventral aspect of disc and arms; G. detail of jaw; H. dental plate from tip of jaw; I, J. oral plates(half-jaws); I. abradial face; J. adradial face. AS, adoral shield; ASS, adoral shield spine (often described as oral tentacle scale); CPP, central primary plate, DAP, dorsal arm plate; M, madreporite, OS, oral shield, RPP, radial primary plate; RS, radial shield; SA, spine articulation; TS, tentacle scale; VAP, ventral arm plate. Scale bars in millimetres.
Figure 4.
Comparison of juvenile and adult morphology.
Ophiopleura borealis. SEM images. A. early postlarva, lacking dorsal arm plates, interradial disc scales and radial shields, madreporite lateral; B. small (young) adult, scales partially obscured by thickened skin. LAP, lateral arm plate; TP, terminal plate. Scale bars in millimetres.
Figure 5.
Diversity of ophiuroid skeletal elements: jaws, dental and genital plates.
A–E. oral plates (half-jaws), abradial face; A. Ophiura sarsii (Ophiuridae), strongly elongated; B. Ophiothrix fragilis (Ophiotrichidae), short jaw with branch-like ornamentation; C. Ophiocoma erinaceus (Ophiocomidae), short jaw with striations; D. Ophiacantha bidentata (Ophiacanthidae), weakly elongated; E, Ophioderma longicauda (Ophiodermatidae), strongly elongated. F–J. dental plates, external (proximal) face; F, O. sarsii, multiple openings per tooth; G. O. fragilis, different areas for tooth papillae and teeth; H. O. erinaceus, different areas for tooth papillae and teeth; I. O. bidentata; J, O. longicauda, dental plate consists of several pieces; K–U. genital plates. K–L. O. sarsii; K, genital plates articulating with radial shields; M–N. O. fragilis; O–P. O. erinaceus; Q–R. O. bidentata; S, O. longicauda; T–U. Amphiura chiajei (Amphiuridae). ad, adradial; ab, abradial; am, articulation to arm; m, muscle attachment area; RS, radial shield.; to, tooth socket; tp, tooth papillae area; Scale bars in millimetres.
Figure 6.
Diversity of ophiuroid skeletal elements: lateral arm plates and vertebrae.
A–O. arm vertebrae; A–K. zygospondylous articulation. A–B. Ophiura sarsii (Ophiuridae); C–E. Ophiothrix fragilis (Ophiotrichidae), keeled type; F–G. Ophiocoma erinaceus (Ophiocomidae); H–I. Ophiacantha bidentata (Ophiacanthidae); J–K. Ophioderma longicauda (Ophiodermatidae); L–O. streptospondylous articulation, Gorgonocephalus eucnemis (Gorgonocephalidae); L–M. regular vertebrae; N. first vertebra of a new branch; O. last vertebra before a new branch (N and another similar vertebra articulate with O). P–Z. lateral arm plates. P–Q. O. sarsii; R–S. O. fragilis; T–U. O. erinaceus; V–W. O. bidentata; X–Y. O. longicauda; Z. G. eucnemis, dist, distal; ext, external; g, groove; int, internal; k, keel; m, muscle attachment area; prox, proximal; sa, spine articulation. Scale bars in millimetres.
Table 1.
Species diversity of extant Ophiuroidea, derived from the online “World Ophiuroidea database”, excluding subspecies.
Table 2.
Species richness and endemism of all described ophiuroids across 12 a priori defined regions and four depth strata.
Figure 7.
Global distribution of described species of Ophiuroidea, based on Table 2.