This week’s featured species has an electric personality. The Great Torpedo Ray (Tetronarce nobiliana) is the largest of the 22 electric ray species in the family Torpedinidae. It can grow to nearly 6 feet (1.8 m) and weigh nearly 200 lbs (90 kg) (Tricas et al., 1997; Notarbartolo di Sciara, Serena, Ungaro, Ferretti, Holtzhausen, & Smale, 2009). Typically dark in color, it is often dark blue, brown, or even black in color. Along its back it has two dorsal fins, the second being slightly smaller than the first. And it has a pronounced caudal fins with two distinct lobes (Tricas et al., 1997). As it hovers in the water, it’s like it came right out of any alien sci-fi movie. It has a very UFO-esque feel to it. It definitely ranks high on my list of favorite ray species!
NOAA’s Fisheries Collection (Photographer). (2009). Atlantic torpedo (Torpedo nobiliana) [Digital Image]. Retrieved from https://commons.wikimedia.org/
The great torpedo ray is a skillful hunter. As juveniles, the great torpedo rays remain in shallow waters with soft substrates, choosing to hunt benthic prey items like crustaceans (Notarbartolo di Sciara, et al., 2009). As they become adults, great torpedo rays move into pelagic and semi-pelagic habitats further offshore, where they feed primarily on larger bony fishes (Notarbartolo di Sciara, et al., 2009). It may not seem like they are capable of swallowing large prey items; however, the great torpedo ray can actually distend their jaws, meaning they can push them outwards. This allows the torpedo ray to swallow prey items that may have appeared too large to fit into their mouths before (Bester, 2018). Their jaws are also designed to crush and grab their prey. They have small curved teeth in approximately seven rows in both the upper and lower jaws. These teeth form a pavement-like structure that both grips and crushes prey (Bester, 2018).
Of course, probably the coolest thing about the great torpedo ray is its ability to produce an electrical current and shock its prey! The torpedo ray has electric organs throughout the pectoral disc. These organs keep the upper, or dorsal, side of the ray positively charged, and keep the lower, or ventral, side of the ray negatively charged. Just like a battery has a positive and negative terminal. When a prey item or a predator comes too close, the ray bridges the gap between the positive and negative sides of its body by completing the pathway through the other animal or even using sea water (Tricas, et al., 1997). And how powerful is the great torpedo ray’s shock?! As the largest of the electric rays, they pack the most powerful punch with a shock of up to 200 volts (Tricas, et al., 1997)! Ouch!
thomasgsac (Videographer). (2011 August). Joe finds out why it is called an Electric Ray [Video Clip]. Retrieved from https://www.youtube.com/
The International Union for Conservation of Nature (IUCN) currently lists the great torpedo ray as Data Deficient. There is not enough data about their population size and trend to properly assess any potential threats to their overall status. Currently, there is no active fisheries that directly targets the great torpedo ray in the Atlantic Ocean. They were once the taken for the liver oil; however, that demand has since disappeared with the development of kerosene (Notarbartolo di Sciara, et al., 2009). Today, the great torpedo ray is sometimes taken as bycatch in trawling fisheries, but they are typically discarded at sea and there is very limited data on catch rates. Another potential threat is the degradation or destruction of nursery habitats. This could potentially impact juvenile populations and have a lasting impact on the overall species population. Ultimately, more data is needed to fully assess the health of this species (Notarbartolo di Sciara, et al., 2009).
Authority: Bonaparte, 1835
Family: Torpedinidae; 22 species
Length: 5.9 feet (1.8 m)
Weight: Up to 200 lbs (90 kg)
Habitat: Juveniles prefer shallow water benthic zones with soft substrates or coral reefs; while adults are typically found in pelagic or semi-pelagic zones
Depth: Surface to 2625 feet (800 m)
Reproduction: Yolk-Sac Viviparity
Gestation: 12 months
Litter Range: Up tp 60 pups
Home Range: Wide ranging across the Atlantic Ocean including the Mediterranean Sea
Diet: Juveniles prefer crustaceans and benthic fishes; while adults feed on larger bony fishes and invertebrates
IUCN Status: Data Deficient
(Whitehead, Bauchot, Hureau, Nielsen, & Tortonese, 1984; Tricas et al., 1997; Baino, Serena, Ragonese, Rey, & Rinelli, 2001; Hollingworth, 2005; Notarbartolo di Sciara, et al., 2009)
Thanks so much for checking out Great Torpedo Ray! If you missed last week’s featured species, please be sure to check out the first shark species discovered in 2019, the Lost Shark! If there is a species of shark you’d love to know more about, leave me a comment or send me a message! I would love to do a feature on your favorite species.
Earlier this month, the Shark Fins Sales Elimination Act was introduced by Congressman Michael T. McCaul of Texas. This legislation will ban the buying and selling of shark fins in the United States. While the act of shark finning is illegal in the US, the trade of the fins is not; thus giving the wrongfully obtained fins import and export value on American soil. Conservation legislation needs public support in order to become law and help protect the environment and wildlife. It is so important that you tell your representatives that you care about environmental and wildlife conservation. Here is a prompt from Oceana that you can use to send to your reps! Just fill in your name! It only takes a moment to make a change that will last a lifetime.
The new Ocean For Sharks Shop is open! There’s handmade ocean inspired plush animals, canvas paintings, and of course my children’s book, Winifred the Wondrous Whale Shark, available in print and PDF. Be sure to stop by. Remember proceeds benefit shark research and conservation with a donation to Project AWARE!
Until next time finactics!
Featured Image Source
thomasgsac (Videographer). (2011 August). Joe finds out why it is called an Electric Ray [Screen Capture]. Retrieved from https://www.youtube.com/
Baino, R., Serena, F., Ragonese, S., Rey, J., & Rinelli, P. (2001). Catch composition and abundance of elasmobranchs based on the MEDITS program. Rapp Comm Int Mer Médit, 36, 234.
Bester, C. (2018). Torpedo nobiliana – Discover Fishes. Retrieved January 31, 2019, from https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/torpedo-nobiliana/
Hollingworth, C. (2005). The Living Marine Resources of the Western Central Atlantic. Volume 1: Introduction, molluscs, crustaceans, hagfishes, sharks, batoid fishes, and chimaeras. Volume 2: Bony fishes part 1 (Acipenseridae to Grammatidae). Volume 3: Bony fishes part 2 (Opistognathidae to Molidae), sea turtles and marine mammals. FAO Species Identification Guide for Fishery Purposes and American Society of Ichthyologists and Herpetologists Special Publication No. 5. Fish and Fisheries, 6(1), 89-90.
Notarbartolo di Sciara, G., Serena, F., Ungaro, N., Ferretti, F., Holtzhausen, H.A. & Smale, M.J. (2009). Tetronarce nobiliana. The IUCN Red List of Threatened Species. Retrieved from https://www.iucnredlist.org/species/161580/5456479
Whitehead, P. J. P., Bauchot, M. L., Hureau, J. C., Nielsen, J., & Tortonese, E. (1984). Fishes of the north-eastern Atlantic and the Mediterranean. v. 1.