Species Spotlight: Oceanic Manta Rays vs Spine-Tailed Devil Rays
11 Oct 2019

Species Spotlight: Oceanic Manta Rays vs Spine-Tailed Devil Rays

 

The current knowledge of the oceanic manta rays s is very limited so we have created this blog post in conjunction with Manta Watch New Zealand to raise awareness of the work they are doing to find out more about these majestic creatures.

 

1. Size - Adult oceanic manta rays weigh up to 2,000kg whereas the spine-tailed devil rays reach about 300kg in weight.

 

2. Length - A fully grown oceanic manta ray's wingspan can reach up to 7m whilst spine-tailed devil rays reach to about 2m.

 

3. AppearanceBesides their difference in size, there are some differences in appearance which can help us tell the two apart.

 

On the dorsal (top) surface, oceanic manta rays have a 'T' shape whilst spine-tailed devil rays have a black 'cap' instead.

 

   

Oceanic manta ray (copyright: Jake Hird) and a spine-tailed devil ray (copyright: Department of Conservation)

 

On the ventral (underneath) surface, only oceanic manta rays have black spots on their lower abdomen (if present) whereas spine-tailed devil rays do not.

 

Emmy the oceanic manta ray displaying her black spots

 

4. Stingers – Whilst both are closely related to stingrays, the oceanic manta ray does not have a stinger at the end of its tail whereas the spine-tailed devil ray does. However, they are generally harmless.

 

5. Range – The spine-tailed devil ray is found worldwide in tropical to warm, temperate waters. In New Zealand, they are usually found in waters deeper than 200m in the open ocean. The oceanic manta rays are generally found along the continental shelf in water temperatures of 18°C or more.  

 

6. Population Size – Global population size estimates for both species are lacking as well as population size estimates for New Zealand. Analysis of collection records and sightings data suggest that spine-tailed devil rays are more abundant than oceanic manta rays in New Zealand.

 

7. Diet Both oceanic manta rays and spine-tailed devil rays feed on plankton such as krill, copepods and crustacean larvae. Depending on the concentration of food, these rays may feed in a straight line or barrel roll (somersault) through the water column.

 

8. BehaviourOceanic manta rays are generally solitary (besides for courtship, mating and aggregating at feeding sites or cleaning stations). You are more likely to see spine-tailed devil rays in groups.

 

What you can do:

With thanks to Lydia Green (Manta Watch New Zealand). Cover photo (c) Jake Hird and Clinton Duffy