A large devil ray, up to about 3.5 m across, with a black band behind the eyes and a white-tipped dorsal fin. It comes into the southern Gulf of California in spring and summer to feed on krill, and tagged rays have swum past Cabo San Lucas into the Pacific. It is protected in Mexico and now listed as Critically Endangered worldwide.
Dark blue to blackish on top and white below, with a broad black band across the back just behind the eyes and a white-tipped dorsal fin. The front edges of the wings are straight to slightly convex, and the white of the belly reaches up behind each eye, so it shows from above as a pale crescent. The tail is thin and at least as long as the disc is wide, with a short serrated spine at its base and a row of small white bumps along each side. Like all devil rays, its mouth is under the head, and the two head fins can roll up into horns.
Spinetail devil rays live in warm seas around the world, in coastal and open water from the surface down to 700 m, and in the eastern Pacific they range from Oregon to Chile. Scientists now treat the eastern Pacific rays once called Mobula japanica as the same species. A 1981–1984 study of devil rays caught at fishing camps between La Ventana and Bahía de los Frailes found the spinetail to be the second most common devil ray in the southern Gulf of California (30% of 262 rays), after the bentfin devil ray.
In that study none were seen in March and only a few in April and May; by mid-June large numbers were feeding in surface water close to shore near Punta Arena de la Ventana. They ate almost nothing but one krill, Nyctiphanes simplex, and nearly all were large adults, 1.3 to 2.4 m across, so the area works as a summer feeding and mating ground rather than a nursery. A female has a single pup per pregnancy, 85 to 92 cm across at birth. STRI gives a maximum width of 3.5 m; FishBase lists up to 5.2 m.
Satellite tags on 14 spinetails off La Paz (2004–2008) showed 8 of them leaving the Gulf, mainly by swimming to the southern tip at Cabo San Lucas, then north or south along the Pacific coast. One track covered 1,536 km, and by August and September their main area had moved to Baja’s Pacific side, following the krill.
Source ↗The tagged rays spent 93% of their time in the top 50 m of water and about 57% in the top 5 m.
Source ↗In the Gulf of California, spinetails fed almost only on a single krill species, Nyctiphanes simplex, and their numbers fell in late summer as the krill declined.
Source ↗Citizen-science reports and aerial surveys have recorded groups of up to 75 spinetails in Bahía de La Paz in March and April.
Source ↗Devil rays are fished for their gill plates, the comb-like filters they strain krill with, which fetch high prices as an ingredient in Chinese medicine; the meat, cartilage and skin are also used.
Source ↗In the early 1980s, a seasonal fishery near La Paz caught devil rays with gill nets and harpoons; the wing meat was filleted for food and used as shark bait. Mexico banned keeping devil rays in 2007.
Source ↗Off Los Cabos the spinetail is a ray you see rather than catch, and sightings aren’t something you can plan on. Your best chance is in late spring and summer, when the rays feed in the southern Gulf and travel past Cabo San Lucas toward the Pacific. In the La Paz study they swam at the surface in small groups parallel to the shore, sometimes in water less than 1 m deep. Look for a dark diamond near the surface, wingtips breaking the water, or a white-tipped dorsal fin.
Devil rays filter krill, so nobody targets them on hook and line, but one can be foul-hooked or tangled in line. Keep it in the water, never gaff it or lift it by the head fins, gills or mouth, and use the leader to hold it alongside. Remove the hook only if you can do it safely; otherwise cut the leader as close to the hook as you can and keep any cut line on board. Mexican law requires releasing it.
| Capture (NOM-029) | Catching or keeping devil rays is banned (the rule names this species as Mobula japanica), alive or dead, whole or in parts; any caught by accident must be returned to the water |
|---|---|
| Mexico (NOM-059) | Subject to special protection (Pr) |
| IUCN Red List | Critically Endangered (2025) |
| CITES | Appendix I since March 2026 (Appendix II 2017–2026) |
| CMS (Bonn Convention) | Appendices I and II |
Munk’s devil ray reaches only about 1.1 m across, has no white tip on its dorsal fin and no tail spine, and travels in big leaping schools. The bentfin (smoothtail) devil ray also has a dark band between the eyes and a white-tipped dorsal fin, but the front edge of each wing has a double curve, its skin is smooth and its tail has no spine. The sicklefin devil ray is olive-brown with no dark band, a plain dorsal fin, strongly swept-back wings and a short tail. The giant manta is much larger, with its mouth at the front of the head and white, T-shaped shoulder patches.
Mostly not. The huge leaping schools are Munk’s devil rays. Spinetails usually travel alone or in small groups, although groups of up to 75 have been seen in Bahía de La Paz.
No. They feed on krill, and the spine at the base of the tail is short. FishBase lists the species as harmless to people.
No. Mexican law bans catching or keeping them, and any caught by accident must be released.
Top illustration: Top Anglers. Photos: iNaturalist contributors, credited on each photo.
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