Mobula rays, the oceans’ aerialists

Did you know that the largest migration of any ray in the World occurs every year in Baja, Mexico? It is one of our favorite events of the year. Who are they? The correct common name is Munk’s Pigmy Devil Ray (Mobula munkiana). In this blog post we will talk about its biology, conservation and some fun facts of Mobula Rays!

I always like to start with the basics, what are Mobulas? (if this is too nerdy for you, skip this paragraph, sorry I can’t help it, I’m a marine biologist). They are vertebrate animals that belong to the class Chondrichthyes, which are fishes whose skeleton is made out of cartilage, unlike humans’ which is made out of bone. This group includes sharks, rays and chimaeras. The rays, also called Batoidea, differentiates from sharks and rays because they have particular characteristics that are unique to them, such as having a flat body and gills positioned under the pectoral fins. There are 10 species of Mobulas (genus Mobula), here we will explore the smallest of all, Mobula munkiana.

What are they doing in Baja anyways?

This is a question that local scientists have been trying to answer. Mobula Conservation has found some interesting information. We know that they aggregate in hundreds or thousands and migrate to the Sea of Cortez during the spring months. We have also seen them do courtship behavior and lots of jumping in the air. But it wasn’t until 2021 when a very complete study was published where they suggest that they are coming here to mate and give birth! This is huge!

Apparently the mating and pupping season begins in April, when the water is warmer. This allows the neonates and juveniles to use shallow bays where there is food available and protection from open ocean predators. These bays are nursery areas, where the young Mobulas will spend their first months of life until they are big and strong enough to start aggregating and joining the Mobula migration.

Why do Mobula Rays jump?

They can jump up to 3 m in the air! Some of the hypothesis scientists have made include: mating behavior, to remove parasites, as a form of communication and for fun. I personally believe that they really want to fly and won’t give up.

Hundreds can jump at the same time, which is super fun to watch.  It sounds like popping popcorn, quite the spectacle! They not only jump but do backflips, 360s, flips, flops, turns… that’s why people call them the oceans’ aerialists.

What do Mobulas feed on?

Mobulas are filter feeders, so don’t worry they won’t try to eat you! They feed on tiny animals floating on the water column called zooplankton. In Mexico they have been found to feed mostly on planktonic crustaceans like Euphausiids and Copepods.

Mobula Mating behavior

Mobulas have a complex mate choice system. Their courtship can last several days where females are chased by different males. The male winner bites the pectoral fin of the female to be able to copulate.

Main threats for Mobulas, and Conservation efforts

Mobulas are threatened by many different factors. They are particularly vulnerable because they have only one pup per litter possibly every 3-5 years. They start reproducing probably at around 5-6 years of age and have a lifespan of around 20 years. So do the math, they are not having a lot of offspring in their lifetime. Add to the equation the fact that they migrate in up to thousands of individuals and they become particularly vulnerable to overexploitation, specifically fishing and bycatch. They are often found as bycatch in tropical tuna purse seines and longlines (the most common ways to fish tuna), so next time you eat sushi think twice! Climate change, pollution, illegal fishing and bad tourism practices are also some of the threats that Mobulas go through.

However it is not all bad! Luckily in Mexico they have been protected since 2004  against capture (fishing), trade and consumption. This is regulated by the law NOM-029-PESCA-2004. To conserve an animal you need to know them first. Mobula Conservation has a citizen science program, where you can help get data about them during our tours!

See them for yourself!

Mobulas are fascinating, so why not enjoy watching them in their natural environment? We run daily trips from Thursday to Sunday in May and June. Come join us and watch these pancakes shoot up to the sky, swim with them, watch them engage in mating behaviors and maybe even predation.

We have small groups of usually 4 but up to 6 people per day. Our guides are trained to show you the best way you can interact with them to have a respectful behavior towards them which will make them stay with us longer! If you want to swim with these incredible creatures, let us know!