A Look into the Mind-Boggling Fauna of Islas Marías

Islas Marías is a living archive of Earth's evolutionary marvels, teeming with more than 350 species of fauna—from elusive sharks to fearless rabbits that don't flee at the sound of human footsteps. This breathtaking diversity serves as both a sanctuary and a challenge.

A Look into the Mind-Boggling Fauna of Islas Marías
A Golden Blue Snapper swims gracefully near a coral reef, embodying the vivid colors and diversity of marine life in Islas Marías.

Set amidst the aquamarine embrace of the Pacific Ocean, the Islas Marías archipelago is not just a stunning geographical wonder—it's also a hotbed for marine biodiversity. This tropical Eden, located about 60 miles (ca. 97 km) off the coast of mainland Mexico, teems with an array of sea life that ranges from the common to the exotic. Much of this is vital to both local ecosystems and larger oceanic networks.

It's important to broaden the lens and recognize that Islas Marías is a microcosm of biological diversity that extends far beyond its underwater realms. Astoundingly, this archipelago is home to more than 350 species of fauna. The eclectic mix includes 78 birds, 21 sharks, 4 species of turtles, 10 rays, 16 species of corals, 32 sponges, 38 annelids, 30 mollusks, 10 echinoderms, 21 sharks, 10 marine rays, 7 marine mammals, 21 terrestrial mammals, 4 amphibians, 19 reptiles, 23 arachnids, and 60 insects.

This staggering variety makes the Islas Marías not just a haven for biologists and environmental scientists but also a living archive of Earth's evolutionary marvels. What's even more fascinating is that many of these species display behavioral patterns that are unique to this specific region. Take, for instance, the local rabbit populations; unlike their mainland counterparts, who are usually skittish around humans, the rabbits here show an intriguing lack of fear. They neither run nor flee at the sound of human footsteps, a spectacle that charms visitors and experts alike.

The lack of skittishness in creatures like the rabbits may signify a relatively low level of human interference, emphasizing the untamed nature of the Islas Marías. This is both heartening and cautionary. On the one hand, it gives us a glimpse of how fauna might interact in ecosystems largely untouched by human activity; on the other, it serves as a reminder that such pristine conditions are increasingly rare and should be diligently protected.

Let's delve into a curated list of the fascinating fauna you can find in these vibrant waters. Consider this your primer on what could well be one of the world's last untamed aquatic frontiers.

Lowland Jack Mackerel (Seriola lalandi)

As you navigate the waters surrounding Islas Marías, one of the first species you're likely to encounter is the Lowland Jack Mackerel. Known scientifically as Seriola lalandi, this fish is often found in schools and is an essential part of the food chain, serving as prey for larger predatory species.

Anchovy (Trachurus symmetricus)

Don't let the Anchovy's modest size fool you; these small fish, identified by their scientific name Trachurus symmetricus, play an enormous role in nutrient cycling. Frequently found in large schools, they serve as a dietary staple for a variety of marine predators.

Golden Blue Snapper (Lutjanus viridis)

Characterized by its captivating hue, the Golden Blue Snapper, or Lutjanus viridis, is a sight to behold. Typically found near coral reefs, this species is popular among recreational anglers and contributes to local fisheries.

Silver Crabs (Genus Gerres)

These crustaceans, belonging to the Genus Gerres, add a touch of metallic sheen to the marine landscape. Though not as popular as other crab species, they serve an essential role in the ecosystem, regularly acting as scavengers that help keep the sea floor clean.

Burra Clam (Spondylus limbatus)

This particular clam species, known as Spondylus limbatus, is prized for both its meat and its intricate shell, often used in local art and jewelry. They serve as filter feeders, thus playing a role in maintaining water quality.

Royal Snail (Hexaplex regius)

With a name fit for a king, the Royal Snail (Hexaplex regius) does not disappoint. It's renowned for its beautifully patterned shell and is frequently a target for shell collectors and underwater photographers alike.

Mexican Dancerina (Elysia diomedea)

The Mexican Dancerina is a type of sea slug distinguished by its vibrant coloration and unique movements, which resemble a dance. Scientifically known as Elysia diomedea, it’s a marvel for those interested in marine biology and underwater photography.

Wrist Butterfly Fish (Chaetodon humeralis)

This uniquely named fish, Chaetodon humeralis, is easily recognizable by its bright colors and patterns. Generally found in and around coral reefs, it's a popular subject for underwater photography and has become an icon of tropical marine life.

Humpback Parrotfish (Scarus perrico)

The Humpback Parrotfish, or Scarus perrico, stands out with its vivid colors and distinct beak-like mouth, which it uses to graze on algae on coral reefs. In doing so, it plays a critical role in maintaining the health of these fragile ecosystems.

Lion's Paw Clam (Nodipecten subnodosus)

Named for its lion's paw-like appearance, this clam species is another local delicacy that contributes to both the ecosystem and the local economy. It’s scientifically known as Nodipecten subnodosus and its presence indicates a healthy marine environment.

Chinese Hat Snail (Crucibulum scutellatum)

The Chinese Hat Snail gets its name from the hat-like shape of its shell. A captivating species for marine enthusiasts, its unique form makes it a fascinating subject for study and collection.

Hawksbill Turtle (Eretmochelys)

Finally, the endangered Hawksbill Turtle makes occasional appearances around Islas Marías. Known scientifically as Eretmochelys, these turtles are a critical indicator species, offering insights into the overall health of marine ecosystems.

A fearless rabbit stands still, unperturbed by human presence.
A fearless rabbit stands still, unperturbed by human presence, offering a glimpse into the untouched and serene ecosystems of Islas Marías.


Islas Marías is a crucible of life in all its dazzling forms, a reminder that our planet, despite its fragility and the manifold threats it faces, is still capable of breathtaking beauty and diversity. From the smallest arachnid to the most majestic marine mammals, from fearless rabbits to endangered turtles, every inhabitant contributes to an ecological tapestry that is nothing short of miraculous.

As we navigate the complexities of the 21st century, marked by climate change, habitat loss, and biodiversity crises, the Islas Maria's stand as both a sanctuary and a challenge. A sanctuary of life as it could be, and a challenge to preserve this treasure for future generations. Let's pledge to uphold the sanctity of this natural wonder, for in doing so, we contribute to the wellbeing of our planet's immeasurably valuable ecosystems.

Source: González Madruga, C. D. (2020). Islas Marías libro-guía de turismo (1st ed.). Secretaría de Turismo.