The Glowing Pocket Shark: A Tiny Marvel from the Deep

Elle
Sep 7
5 min read

Updated: Sep 20

Imagine holding a creature so small it could fit in your pocket, yet so extraordinary it glows like a living constellation in the pitch-black depths of the ocean. Meet Mollisquama Mississippiensis, the newly discovered American pocket shark, found in the Gulf of Mexico and only the second pocket shark species ever known to science.

A Glowing Discovery in the Deep

The American pocket shark was collected in February 2010 during a NOAA mission to study sperm whale feeding in the eastern Gulf of Mexico. However, it wasn't until years later that scientists realized they had discovered an entirely new species. At just 5.5 inches long, this remarkable creature is one of only two pocket shark specimens known to science, and amazingly, it also glows in the dark.

What makes this discovery even more remarkable is the rarity of these sharks. Only two pocket sharks have ever been caught from the ocean, with the previous specimen, M. parini, collected from the eastern Pacific. Finding a second species thousands of miles away in the Gulf of Mexico shows just how much we still don't know about our ocean's mysterious inhabitants.

Why It's Called a "Pocket Shark"

Don't let the name fool you. The pocket shark isn't called that because of its tiny size, though it certainly could fit in your pocket. The pocket shark gets its common name from a small pocket gland found behind each pectoral fin on either side of the shark. The purpose of this gland is still unknown as not enough specimens have been found to investigate the matter.

This mysterious pocket-like organ sets these sharks apart from all other species. Scientists believe it might produce bioluminescent chemicals, help with communication, or serve some other function we haven't yet discovered. The fact that we're still puzzling over basic questions about these creatures shows just how much the ocean still has to teach us.

What Makes a Shark Actually a Shark?

Before we dive deeper into the pocket shark's amazing features, it's important to understand what makes any fish an actual shark. Not all fish with "shark" in their name are actually sharks, and the pocket shark definitely qualifies as the real deal.

Sharks are a special type of fish known as "elasmobranchs," which translates into fish made of cartilaginous tissues. This category also includes rays, sawfish, and skates. Here are the key features that make a fish a true shark:

Cartilaginous Skeleton: Instead of bones, sharks have skeletons made entirely of cartilage (the same flexible material that makes up your ears and nose tip). Their cartilaginous skeletons are much lighter than true bone. Cartilage is less dense than bone, allowing sharks to move quickly through the water without using too much energy.

Gill Slits: Sharks are characterized by having five to seven gill slits on each side of their head. Unlike bony fish, sharks don't have a protective gill cover called an operculum.

Dermal Denticles: Sharks have dermal denticles covering their skin. These are tiny, tooth-like scales that give shark skin its characteristic rough texture and help them swim more efficiently.

Body Structure: Sharks have pectoral fins that are not fused to the head and a ribless endoskeleton. While skates and rays also have cartilaginous skeletons, sharks have very different body shapes from the flattened, disc-shaped bodies of rays.

Blood Production: Since they don't have bone marrow, red blood cells are produced in the spleen.

A Living Light Show

One of the most fascinating aspects of the American pocket shark is its ability to produce light. In the eternal darkness of the deep ocean, where sunlight never penetrates, many creatures have evolved the ability to create their own illumination through a process called bioluminescence.

The pocket shark joins an exclusive club of glowing sharks. Scientists believe the light-producing organs, called photophores, scattered across its body help it communicate with other sharks, confuse predators, or attract prey. Picture this tiny shark swimming through the inky depths like a living constellation, its body twinkling with dozens of small lights.

This bioluminescence is particularly important for survival in the deep sea. In a world where darkness reigns supreme, the ability to produce light can mean the difference between finding food and becoming food for someone else.

The Challenge of Deep-Sea Discovery

The rarity of pocket shark sightings highlights one of marine biology's greatest challenges: studying life in the deep ocean. The depths where these sharks live are more remote and difficult to explore than the surface of Mars. The crushing pressure, complete darkness, and extreme cold make every expedition a technological marvel.

The discovery was made possible through a partnership between Tulane University and NOAA, which may lead to additional discoveries in the future. This collaboration shows how important it is for different institutions to work together when exploring Earth's final frontier.

What This Discovery Means

Finding the American pocket shark teaches us several important lessons about our planet's biodiversity. First, it reminds us that we've only scratched the surface when it comes to cataloging life in our oceans. Scientists estimate that we've only discovered a small fraction of the species that live in the deep sea.

Second, it shows us how evolution has created incredible solutions for surviving in extreme environments. The pocket shark's small size, bioluminescence, and mysterious pocket organs represent millions of years of evolutionary adaptation to life in one of Earth's most challenging habitats.

Finally, this discovery emphasizes how much we depend on healthy ocean ecosystems. Every new species we find adds another piece to the complex puzzle of marine food webs. Even a tiny shark like the pocket shark plays an important role in its deep-sea community.

The Future of Deep-Sea Exploration

The details of the new species are described in an article published in the animal taxonomy journal Zootaxa. This formal scientific description allows researchers around the world to learn from this discovery and potentially find more pocket sharks in other parts of the ocean.

As technology improves, we'll likely discover many more incredible creatures like the pocket shark. New deep-sea exploration tools, including advanced submersibles and underwater cameras, are opening up previously impossible areas of study. Each expedition into the deep sea has the potential to reveal species that could revolutionize our understanding of life on Earth.

The story of the pocket shark reminds us that our planet still holds countless mysteries waiting to be discovered. In an age when it sometimes feels like everything has been explored and catalogued, the deep ocean continues to surprise us with creatures that seem almost too fantastic to be real.

Who knows what other glowing, pocket-sized marvels are swimming in the darkness below, waiting for their moment in the spotlight?