Overview

Manta rays are widely distributed, migratory, and have unique spot patterning on their underside that can be used to identify individuals. MantaMatcher is the first global online manta ray database, managing manta ray sighting and identifications worldwide. Any diver or snorkeler with a camera can take and upload a manta identification photo. Researchers can also upload and organize individually identified manta rays in the regional populations they are managing. MantaMatcher also promotes collaborations by way of cross-referencing different study sites. Scientists can now examine if populations are shared between neighboring countries, examine regional and long distance movements, and examine the lifespans of manta rays.

A sophisticated algorithm is used to match manta identification photos automatically. The algorithm works like facial recognition software for manta bellies. By automating much of the identification process researchers can match mantas regionally, and even globally, with ease. Researchers will ultimately be able use sightings data to determine the abundance, trends, movements, and population structure of manta ray populations at individual aggregation sites across the globe.

Uploads to MantaMatcher have already contributed to our better scientific understanding of these species. A paper on manta migrations in Indonesia, using data sourced from MantaMatcher, was instrumental in achieving protection for mantas across all of Indonesia's waters. Data from MantaMatcher were also used as scientific justification for Convention on Migratory Species listing of reef mantas (Manta alfredi) in November 2014.

You don't need to be a researcher to contribute. Any diver or snorkeler with a camera can identify an individual manta ray. By uploading your manta identification photos, and information about your manta encounter, you too can help global manta ray research and conservation.

Citation

Marshall AD, Holmberg J (2018) MantaMatcher Photo-identification Library https://www. mantamatcher.org Downloaded on YYYY-MM-DD.

About mantas

Did you know that the natural spot patterns on the underside of manta rays can be used to distinguish between individuals like a fingerprint? Researchers are now using these natural markings to keep track of different population and examine their movements around the world. Contributing to this ongoing work is a way for the public to engage in what we like to call “Citizen Science”. We cannot do this alone and we are asking for the public to help us solve some of the mysteries of mantas by adding photos to our global database.

Below we explain a little more about the different species of Manta and outline the best ways to photograph these animals in the world and upload your photos to our website.

Different species of manta

Currently two different species of Mantas are recognized, and it will be important to note which species you have observed. Luckily the two species can be visually differentiated and the following guide will help you distinguish between Manta alfredi and Manta birostris.

Fig 1. Differences between manta species

Reef mantas (Manta alfredi) can be found in all three of the world's major oceans but are most commonly encountered in the Indian Ocean and south Pacific. Key aggregation sites include: Hawaii, Australia, Komodo, Maldives, Yap, Palau, Bali, and Southern Mozambique.

• Manta alfredi is the smaller of the two species and does not exceed 5 meters (16.5 feet) disc width (which is the distance between the two wing tips).
• Their underside is predominantly white with the exception of their unique spot and patch patterning. These natural marks can be found on the pectoral fins, the stomach, and in-between the gill slits. Their mouths are most commonly white in colour. See figure 3 for examples of variation in its underside colouration.
• The topside of Manta alfredi is predominantly black with light patches particularly around the upper back. We refer to these marks as shoulder patches. In Manta alfredi these patches can be prominent or very faint but it is their general shape that is used to differentiate them from Manta birostris. See figure 2 for examples of variation in the shoulder patches of Manta alfredi.
• Does not have remnant stinging spine at the base of the tail (figure 6).

Fig 2. Dorsal surface of Manta alfredi

Fig 3. Ventral surface of Manta alfredi

The giant manta (Manta birostris) is the most widely distributed manta ray and is found in all three of the world major oceans. This species is commonly encountered at offshore islands and seamounts. Key aggregation sites include: Southern Brazil, Ecuador, Thailand, Egypt, Southern Mozambique, and Mexico (Pacific Ocean).

• Manta birostris is the larger of the two species reaching up to 7 meter disc width (23 feet).
• Their underside appear much darker than Manta alfredi as they have dark faces/mouths and a dark V-shape along the trailing edge of the pectoral fins. They also have natural spot patterning on their undersides but the spots and patches always occur centrally on the stomach area and doe not extend between the gill slits or far out on the pectoral fins. See figure 3 for examples of variation in its underside colouration.
• The topside of Manta birostris is predominantly black with light patches on the upper back. We refer to these marks as shoulder patches. In Manta birostris these patches are bright and prominent. Their general shape that is used to differentiate them from Manta alfredi. In this species the shoulder patches look like distinct triangles. See figure 4 for examples of variation in the shoulder patches of Manta birostris.
• Has remnant stinging spine at the base of the tail (figure 6).

Fig 4. Dorsal surface of Manta birostris

Fig 5. Ventral surface of Manta birostris

Fig 6. Remnant spine in Manta birostris

Colour morphs

To make matters slightly confusing, two distinct colour morphs have been identified in manta rays, black mantas and white mantas. A genetic disorder causes these different colour variants and both conditions are rare.

Black mantas, or melanistic mantas, have an entirely black topside, and a predominately black undersides except for a variably sized white blaze along its mid-line.

White mantas, or leucistic mantas, have a reduction pigment making their skin appear lighter, even white.

Don't worry if you have doubts about identifying the animal you encountered or uploading your ID shots. If you do not feel comfortable assigning a species or coluration type when you upload your photo, our trained staff will do it for you. Simply click on “unsure” or “unknown” when prompted.

Fig 7. Colour morphs in mantas

Determining sex and maturity

Determining the sex of a manta is usually quick and easy. If you have taken a good ID shot of the standardized area, you will be able to ID the animal's sex from this photo. If not, check your other photos to see if you can see the pelvic fins. Pelvic fins are the two small fins located at the rear of the animal by the tail.

Fig 8. Determining sex

Female manta rays do not have any external reproductive organs so all that you will see in the image will be fins. Because there are no organs to judge by, determining the maturity status of a female ray can be difficult. If the individual was visibly pregnant or possessed reproductive scars (bite marks obtained during mating) on either or their wing tips then they can be classified as mature.

Fig 9. Sexual maturity in females

Male manta rays do have external reproductive organs, call claspers, that protrude off of these pelvic fins. Immature males will have small claspers and mature males will have large claspers that protrude past the edge of the pelvic fins.