#dasyatidae

Blue-spotted Ribbontail Ray (Taeniura lymma), family Dasyatidae, order Myliobatiformes, off of Tioman Island, Malaysia

Blue-spotted Ribbontail Ray (Taeniura lymma), family Dasyatidae, order Myliobatiformes, off the coast of Egypt

NEW SIGHTINGS OF THE DIAMOND STINGRAY IN CHILE: A HIDDEN SPECIES REVEALED WITH HELP FROM FISHERMEN

The diamond stingray is easily recognized by its diamond-shaped body, smooth skin with few spines, and long tail armed with a venomous barb. This species has a broad distribution, ranging from southern California to northern Peru, where it is relatively common. However, until recently, its presence in Chile was only known from a single record dating back to the 1980s.

Thanks to photographs shared by recreational shore fishermen, the presence of the diamond stingray has been confirmed along the entire Peruvian coast and the northernmost regions of Chile. Researchers used social media platforms to search for photographs of rays and sharks, identifying that this species had been regularly captured in the region. By combining these new sightings with historical distribution data, scientists employed ecological modeling tools to predict the potential habitats of the diamond stingray in its southern range.

While this discovery confirms the presence of the diamond stingray in Chile, it also raises new conservation concerns. This species is not currently protected by Chilean legislation and faces several threats, including habitat destruction, entanglement in fishing gear, and overfishing due to its slow growth and low reproductive rates. The species is listed as Vulnerable by the IUCN, highlighting the need for increased conservation efforts. Fishermen and divers who contribute photographs through social media serve as valuable sentinels, providing critical data for researchers, but much about the ray’s ecology and the specific threats it faces in Chile remains unknown. Further research and targeted conservation strategies are needed to safeguard this species and its newly identified habitats.

Photo: Oceanfreaks Dive Center

A Stingray Abroad: The Broad Stingray

Bathytoshia lata is a stingray known by many names: the broad stingray, the brown stingray, and thorn tail stingray; Dasyatis lata, Dasyatis thetidis, and Dasyatis ushii. The species has accumulated all these names-- and quite a few others-- thanks to its broad distribution. It can be found in the Atlantic, Pacific, and Indian Oceans, as well as the Mediterranean sea. Typically the species stays on reefs or in coastal bays with muddy bottoms. Prior to 2012, genetic testing of stingray species revealed them to be populations of B. lata, hence the multitude of latin names.

The broad stingray is one of the largest species of stingrays; the average individual is about 1.5 m (5 ft) across and 56 kg (123 lb), with some populations reaching an excess of 2.6 m (8.5 ft) across and 290 kg (639 lbs). Females also tend to be larger than males. The body is diamond shaped, and the tail is often more than twice its length. B. lata is dark in color, often tan or black, with a white underbelly. Perhaps its most distinctive feature are the 'spines'-- also known as dermal denticles-- that line the tail and rear portion of the body, giving it the name 'thorn tail'.

The brown stingray is fairly docile, and spends most of the day lying inactive on the sea bed. At night they forage for crustaceans, polychaete worms, and small fish. They can use their powerful pectoral fins to burrow through the sand and uncover prey, and like sharks they have special organs called ampullae of Lorenzini that allow them to detect electrical fields emitted by their prey. The primary predator of B. lata is the hammerhead shark, and when threatened individuals will raise the spines along their tail to deliver whip-like blows.

Females become ready to mate in the summer, typically from November to March. Males are attracted to pheromones released by the female, and initiate a dance-like courtship ritual. If the female is receptive, he will bite down on her pectoral fins while grasping her with special claspers located at the base of the tail. Following the mating ritual, the female gestates her young internally for 10-12 months. This species is ovoviviparous, and the pups recieve nutirents from both a yolk and internally secreted milk. Following her pregnancy, the mother gives birth to live young, typically 3-4 in a litter. The pups are completely independent, and receive no parental care after being born. It takes them about 14-16 years to become fully mature, and individuals can live up to 28 years in the wild.

Conservation status: The broad stingray is considered Vulnerable by the IUCN. Its most common threat comes from being caught as by-catch in fishing nets, and intentionally for their meat and skin.

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Photos

Andy Murch

Sarah Speight

Andrew Green

Surprisingly enough, mammals aren't the only animals that provide their young with milk! The giant freshwater stingray is one of several species of cartelaginous, live-bearing fish that sustain their young to term through a form of maternal care called histotrophy, in which the mother provides her embryo(s) with nutritional, milk-like secretions known as trophonemata while they're in the uterus.

(Image: A giant freshwater stingray (Urogymnus polylepis) caught and released by Cambodian fishermen, by Chhut Chheana)