Taxonomy

Rarity

The pelagic stingray is the 1 ray on this coast that never touches the bottom. Every other ray and skate on this site is a flat animal built to lie on sand, mud or rock, and this one spends its entire life in open water over depths it will never reach. FishBase describes it as possibly the only fully oceanic member of the stingray family, and that single fact is why it has a page here.

California is inside the range and the species is documented off this coast, but no California abundance figure, survey or record count was found, so how often one is actually here is unknown. What the sources do establish is how a person on this coast would meet one, and it is not on a dive. Pelagic stingrays turn up as a common bycatch of the offshore longline and drift-net fisheries chasing tuna and swordfish, and California is named specifically alongside Hawaii and Oregon in that context. A reader who encounters this animal will be a long way offshore, looking at it alongside a boat.

The International Union for Conservation of Nature assessed the species as Least Concern in 2018. It is globally common and supports a commercial fishery for its meat and sometimes its cartilage. In California it has no rule of its own and falls under the general ocean finfish limit of 20 fish in combination with no more than 10 of any one species, with no minimum size. Unlike the skates and the ratfish, it is not a federally managed groundfish, which is what a fish that never goes near the ground should expect.

Seasonality

Location

The pelagic stingray is probably cosmopolitan, found in tropical and subtropical seas worldwide between roughly 52 degrees north and 50 degrees south. In the eastern Pacific it has been reported from Vancouver, from California and Baja California south to Chile, and around the Galapagos Islands, and it occurs in the Atlantic, the Mediterranean and the Indian Ocean as well.

The habitat is defined by what it lacks. There is no bottom in it. The species lives over deep water and usually stays in the upper 330 feet, with records to about 1,250 feet, all of it in the open water column. It wants water warmer than 68 degrees, and a study of the Pacific high seas found the highest presence associated with slightly low salinity and moderately high chlorophyll, meaning water with some productivity in it rather than the clear blue desert farther out.

That temperature threshold is the practical rule for this coast. Southern California surface water reaches 68 degrees in late summer in warm years and not much of the rest of the time, so if this animal is here at all it is a late-summer and fall visitor rather than a resident. The same high-seas study found something counterintuitive that is worth reporting with its limits attached: presence dropped during both the cold phase and the strong warm phase of the El Nino Southern Oscillation, the recurring Pacific-wide warming and cooling cycle. That work covered the Pacific high seas, not the Southern California Bight, so it is not a prediction about what this coast will see in any given El Nino year.

Identification is unmistakable if one is ever alongside a boat. The disc is thick and angular with a broadly rounded snout, and the whole animal is a uniform violet, purple or dark blue-green on top and underneath, with no markings anywhere. The tail is shorter than twice the body length and carries what FishBase calls 1 extremely long sting. The disc has no thorns and the eyes do not protrude.

The uniform color is the detail that repays a moment's thought. Almost every ray on this coast is dark above and white below, which is the standard arrangement for an animal that is viewed from above against a dark bottom and from below against bright sky. A ray in open water has no bottom behind it, and the eyes that do not protrude tell the same story: a bottom-dwelling stingray needs eyes raised on the disc so it can see while buried in sand, and an animal that never buries itself does not.

Size runs to about 38 inches across at the maximum, with 31 inches the more usual figure for a large one.

Deep Dive

What this ray eats is the most surprising thing about it. The prey list includes krill and amphipods, which are small shrimp-like crustaceans drifting in the water column, along with jellyfish and their relatives, squid, octopus and small fish. A stingray that lives on plankton and jellyfish has abandoned the entire feeding strategy of its family. Bottom-dwelling stingrays crush shellfish and dig worms out of sediment with flat grinding teeth. This one intercepts soft, drifting food in open water, and the Florida Museum records that it sometimes uses its enlarged pectoral fins to move food into its jaws, herding prey toward the mouth with the leading edges of its wings.

That behavior is the mechanical answer to a real problem. A ray's mouth is on the underside of its body, which works perfectly for an animal lying on top of its food and works badly for one chasing jellyfish through open water. Bottom-feeding rays get their prey by settling over it. A pelagic ray has nothing to pin food against, so the wings do the pinning.

Reproduction is live-bearing, and the pace is faster than any other ray in this Ichthyopedia. Litters run from 2 to 9 pups, each 6 to 10 inches across at birth, after a gestation of about 4 months. Compare the bat ray at 9 to 12 months and the Pacific electric ray, whose females breed only every second year. Sources differ slightly on the lower bounds here, giving either 2 or 4 as the minimum litter and either 4 months or 2 to 4 months for gestation, so the numbers are not settled. The pattern is clear enough regardless: a short pregnancy and small litters, in an animal that matures at around 18 inches, roughly half its maximum width. Fast maturity and a short gestation are part of why a species taken constantly as longline bycatch is still rated Least Concern.

The spine is real and the risk is not. This is a genuinely venomous ray with one of the longest stings in the family, positioned about a third of the way down the tail, and the Florida Museum is direct that these are defense weapons. It is also an animal almost nobody shares water with. The danger is described as minimal precisely because the species lives where people do not swim, and the injuries that do happen are to fishermen handling a ray that has come aboard on a line. Nothing about this species belongs in the same conversation as the round stingray, which is the ray that actually stings people in California, and it stings them in 3 feet of water off a sand beach.

Set the 2 members of this family that appear in this Ichthyopedia against each other and the comparison is worth the space. The diamond stingray lies on mud and sand near reefs and kelp off Southern California, rare in California waters and more at home from Baja south, dark above and pale below, eyes raised to watch from under the sediment. The pelagic stingray is the same family solving the opposite problem: uniform violet on both sides, flat eyes, wings used as hands, feeding on drifting animals in the top few hundred feet of open ocean, and never once in its life resting on anything.

Where to Find Them

Beaches whose habitats match this species

Matched by habitat: a beach is listed when its biome tags overlap this species' biomes.