Blue stingray
A southern African whiptail stingray with blue markings.
The blue stingray (Dasyatis chrysonota) is a whiptail stingray from the Dasyatidae family, commonly found in southern Africa’s coastal waters. Its light-brown, triangular disc is marked with faint blue splotches and lines, making it easy to tell apart from other stingrays. The species ranges geographically from St. Lucia at Africa’s southern tip up to Angola, and in depth from the surf zone down to 110 meters. It has also been spotted off Israel’s Mediterranean coast and in the Gulf of Gabès off southern Tunisia.
The disc can reach a maximum width of about 75 centimeters. Four size classes exist: small (under 30 cm), medium (30–45 cm), large (45–60 cm), and very large (over 60 cm). Males and females show no size difference from birth until adolescence, around age four, when sexual differences emerge. After that, females grow faster than males. Males reach maturity at a minimum age of five, females at seven. Age is estimated from vertebral centra, which show narrow dark bands and wide translucent bands that bunch together. Seasonal changes in temperature and light likely control growth and band formation, with warmer months producing faster growth. In captivity, one opaque and one translucent band form each year, similar to the related diamond stingray (*Dasyatis dipterura*).
The blue stingray occupies different habitats over its life and feeds opportunistically on a wide variety of benthic epifauna and infauna. Prey proportions shift with size class, likely because larger rays can dig deeper into sediment—like the bat ray (*Myliobatis californica*)—while smaller ones are limited. Main prey groups include crustaceans, molluscs, polychaetes, and hemichordates, with crustaceans and molluscs being most common among related species. Feeding involves gliding along the ocean surface to search, then landing on prey and drawing it into the mouth with the jaw. Medium and large size classes are important predators in the nearshore sandy beach ecosystem of southern Africa’s surf zone, but very large rays mostly feed nearshore and offshore, primarily on *Callianassa* spp., which are absent from the surf zone.
Males reach sexual maturity at a smaller size and younger age than females. Sperm production peaks from September to December, making the mating season mainly austral spring and part of austral summer.
Quick Facts
- Genus
- Dasyatis
- Species
- chrysonota
Facts from the source article.
Lore & Background
The blue stingray's disc can reach a maximum width of approximately 75 cm, and individuals are classified into four size classes: small (<30 cm), medium (30–45 cm), large (45–60 cm), and very large (>60 cm). Males and females show no size distinction from birth until adolescence (around 4 years old), after which females exhibit a faster growth rate. Age estimates are often made using vertebral centra, which show narrow dark bands and wide translucent bands; seasonal temperature and light fluctuations are likely significant controlling factors in growth rate and band formation. One opaque and one translucent band is formed annually in captivity, similar to the closely related diamond stingray (Dasyatis dipterura).
The species occupies different habitats throughout its lifetime and feeds on a wide variety of benthic epifauna and infauna with an opportunistic feeding strategy. Main prey groups include crustaceans, molluscs, polychaetes, and hemichordates. Medium and large size classes are important predators in the nearshore sandy beach ecosystem of the surf zone, while the very large class feeds mostly nearshore and offshore, primarily on Callianassa spp., which does not occur in the surf zone. The feeding process involves gliding along the ocean surface, landing upon prey, and drawing it into the mouth using the jaw.
Reader's Guide
The blue stingray is a popular target species for recreational and competitive rock and surf anglers as well as recreational ski boat fishers in southern Africa. Despite this popularity, the species is at risk of over-exploitation because there is currently no proper management strategy in place for its protection. Its reproductive success is considered low based on average fecundity and active reproductive lifespan. The species follows an annual reproductive cycle with a nine-month gestation period; ovulation and fertilization occur between January and April, and mating peaks from September to December (austral spring and early summer). An offshore winter migratory pattern—inshore in summer, offshore in winter—coincides with this reproductive seasonality. Courtship and mating behavior is a rare occurrence. Unlike some related ray species, a strong maternal size to litter size relationship does not exist, possibly related to uterus capacity. The species is easily distinguishable from other stingrays by the appearance of faint blue splotches and lines on its light-brown triangular disc body.
Did You Know?
- The blue stingray has been found off the Mediterranean coast of Israel and in the Gulf of Gabès in southern Tunisia, far from its main southern African range.
- Females grow faster than males after about 4 years of age, and reach maturity at a minimum of 7 years, compared to 5 years for males.
- The species has a low fecundity of 1–7 embryos per litter, averaging 2–3, and lacks a strong maternal size to litter size relationship.
More in Reef Sharks and Rays, Part 2 1-24
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