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Rays

AquaFacts: AquaFacts are a resource for students who are looking for information on the animals at the Aquarium or other Aquarium-related topics. Here, we’ve compiled some of the most frequently asked questions that we’ve received about sharks. The answers come from our biologists and from reputable sources that we reference at the end of this page. If you have a question about sharks that’s not addressed in this page or the references below, please feel free to email our librarian.

Ray

Questions & Answers

What is a ray? 

A ray is a fish that belongs to the same group as sharks (together they are known as “elasmobranchs”). Like sharks, rays have skeletons made of flexible cartilage instead of bone.

The term “ray” includes flat sharks, skates, stingrays, sawfishes, electric rays and guitarfishes. There are over 630 identified species of rays with new ones being discovered from time to time.

Rays generally have short, flat bodies with pectoral fins that are joined to the side of their head. They have five to seven paired gill openings underneath their bodies. Some rays have one or more spines (also called barbs) on or near their tail that can inflict painful injuries. Others don’t have a spine at all.

Many rays are benthic fishes, which means they live at the bottom of the ocean, river or lake. Others are open-water (pelagic) rays that swim almost constantly, travelling in large groups and migrating together.

How do you tell a male and female ray apart?

Males have reproductive organs called claspers. Look for finger-like appendages attached to the tail-end of their bodies; females don’t have these. During mating, a male will usually bite a female to hold her alongside his body and use one or both of his claspers to insert sperm into her.

Female rays are generally larger than the males.

Male vs. female

What do rays eat?

All rays are carnivores that mainly eat animals living on the ocean, river or lake floor. Their prey include crabs, shrimps, clams, small fishes, squids and sea urchins.

Open-water (pelagic) rays hunt small fishes and squids, and also octopuses. Notable exceptions are the giant manta (Manta birostris) and a few other smaller species of mobula rays that are plankton feeders. They swim with their mouths wide open and trap plankton in their gill rakers as water moves through their gills. They eat huge quantities of these microscopic animals and plants.

Will a stingray sting me?

No. The stingrays at the Aquarium in the Discover Rays exhibithave their barbs trimmed regularly. Just like people trimming their fingernails, it’s quick and painless.  The stingrays are used to         being touched and fed by people, so they don’t see people as threats. As long as you are gentle, you’ll be fine.

In the wild, problems can arise when humans and rays share space without being aware of each other.Injuries usually occur when a person accidentally steps on a stingray in the shallow waters of a beach. A stingray’s first defense is to swim away; it only uses its barb (also called caudal spine) as a last resort to protect itself. Despite such accidents, incidents resulting in death are rare.

To prevent injury, avoid startling stingrays. Try the “stingray shuffle” by sliding your feet along the sand instead of taking big steps. This sends vibrations to alert the stingrays of your presence so you don’t surprise them.

What ray species are on display at the Vancouver Aquarium?

We have cownose rays (Rhinoptera bonasus) and southern stingrays (Dasyatis americana) on display as part of our Discover Rays exhibit. There are other rays, including freshwater stingrays, on display in other parts of the Aquarium. 

What is the difference between a stingray and a skate?

Look at the area where the tail meets the body of these fishes to see the differences. Under the tail, a stingray has a single-lobed pelvic fin while a skate has a double-lobed pelvic fin. Also, stingrays often have a spine (also called barb), on their tails, while skates do not.

Another difference between these fishes is how they have babies. Most stingrays give birth to live young, while skates lay eggs cases (known as “devil’s pouches” or “mermaid’s purses”) on the sea floor.

Ray vs. skate (see below)

Are rays endangered?

According the IUCN Red List of Threatened Species, a quarter of the world’s sharks and rays are threatened with extinction, with ray species being at a higher risk than sharks. These fish are at a higher risk than most other groups of animals because they tend to grow more slowly and produce fewer young.

Overfishing is the main threat to these animals. Oftentimes, sharks and rays are caught accidentally by fisheries targeting other types of fish, such as tuna. This unintentional catch is called “bycatch.” 

How can I help save rays and their relatives?

Sustainable seafood initiatives, such as the Vancouver Aquarium’s Ocean Wise™ program, help consumers choose species that are caught or farmed in a way that ensures the long-term health and stability of that species and the greater marine ecosystem. Seafood recommended by Ocean Wise can be found in markets and restaurant all across Canada. Within the United States, the Monterey Bay Aquarium’s Seafood Watch program provides sustainable seafood lists designed to raise consumer awareness.

Increased awareness and education of these animals goes a long way as well, which is what you’re engaging in right now by learning more about them.



Facts & References

Key Facts:

  • Largest ray (length): green sawfish (Pristis zijsron), 7.3 metres

  • Largest ray (width): manta ray (Manta birostris), 7 metres

  • Smallest ray: narcinid electric ray (family Narcinidae), 15 centimetres long

  • Deepest-dwelling ray: rajid skate (family Rajidae), 3,000 metres below sea level

Did You Know?

  • Sawfishes can slash their distinctive long snouts, or rostrums, from side-to-side to hit and stun their prey - fishes that travel in large schools.

  • Electric rays have powerful electric organs used to stun their prey. These organs were studied closely by Alessandro Volta, the inventor of the battery.

  • Guitarfish look like a cross between a shark and a skate. Their head is flat like a skate or stingray, but the tail looks like a shark’s tail. So they also look a bit like a guitar, what do you think?

guitar-fish.jpg


References

  1. Klimley, A. Peter. 2013. The Biology of Sharks and Rays. The University of Chicago Press, Chicago, IL.
  2. Ferguson, Ava and Gregor Cailliet. 1990. Sharks and Rays of the Pacific Coast. Monterey Bay, CA: Monterey Bay Aquarium.
  3. Gruber, Samuel H. Ed.1991. Discovering Sharks. Highlands, NJ: American Littoral Society.
  4. Shark Research Institute. October 2007.
  5. Shark Web Site. NOAA Fisheries. October 2007.
  6. Sharks. 1990. New York: Facts on File Springer, Victor, G. Gold, and P. Joy. 1989.
  7. Functional Anatomy of the vertebrates. 2001. California: Brooks/Cole – Thomson Learning.
  8. Bester, Cathleen. Icthyology at the Florida Museum of Natural History.
  9. Florida Museum of Natural History. Ray & Skate Biology. February 2016.
  10. King, J., McFarlane, G., & McPhie, R. (2010). Distribution and life history parameters of elasmobranch species in British Columbia waters. Canadian Technical Report Of Fisheries And Aquatic Sciences, (2908). Retrieved from Fisheries and Oceans Canada.
  11. Fisheries and Oceans Canada. Bedford Institute of Oceanography. Ray & Skate Fast Facts. February 2016

Permission is granted by the Vancouver Aquarium Marine Science Centre for classroom teachers to make copies for non-commercial use. This permission does not extend to copying for promotional purposes, creating new collective works, or resale.

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