Tag: marine biology

Diving To The Bottom Of The Great Blue Hole

Just off the coast of Belize lies a mysterious formation at the bottom of the ocean. The shallow waters of the reef plunge hundreds of feet down into a massive void, appropriately named the Great Blue Hole, into which very few people have ventured.

Remains Of The Past

The origins of the Great Blue Hole, while interesting, aren’t much of a mystery. During Earth’s ice ages, sea levels were much lower. What is now shallow waters off the coast of Belize was once dry land. Throughout Earth’s last several ice ages, a massive sinkhole formed a cave. That cave filled with water and eventually became the Great Blue Hole.

When you get right up close to it, the massive underwater cavern looks somewhat intimidating. The shallow ocean drops off into a deep blue chasm, the bottom of which cannot be seen from the surface. At around 410 feet deep, the Great Blue Hole remained a mystery for some time until a handful of intrepid divers made their way to the bottom.

A Long Way Down

Diving 400 feet below the surface not only takes experience and courage. It’s a journey that requires special equipment to provide enough oxygen to last the entire trip. For reference, standard diving gear only allows the wearer to explore down to about 130 feet. In late 2005, a team of divers from The History Channel set out on the first documented dive to the bottom of the Great Blue Hole.

Their adventure into the belly of the beast confirmed the fact that the cave had been created as a dry landform before being submerged underwater and reemerging again on several occasions to continue its formation. When they finally reached the bottom, the divers landed in soft sediment, which had been deposited by the currents in uneven dunes. Stalactites loomed from overhangs, indicators of a damp past above water. Markings on the rocky formations indicated a series of rising water levels throughout several major climate phases earlier in Earth’s history.

Unusual Finds And Future Adventure

In addition to finding a cave at the bottom of the deep oceanic hole, the divers also found an assortment of crabs strewn about the sand, all of which were dead. The Deep Blue Hole receives minimal circulation in its waters 400 feet from the surface. As a result, they hold very little oxygen. Any creature unlucky enough to tumble in from up above is doomed to meet a grisly demise. Another side-effect of anoxic water is that not much can survive down there to break down dead creatures, so the carapaces stayed behind, preserved after death.

Since 2005, no one has documented another trip to the bottom of the Great Blue Hole. Jacque Cousteau, who originally made the place famous in 1971, and the team from the History Channel are the only people to ever truly explore it. Now, Cousteau’s son, Fabien, plans to explore the depths and gather information from the rock and sediment. His expedition will be documented on the Discovery Channel and will help scientists better understand the geological history of the area.

Life Is Thriving In Earth’s Deep Sea Circle Of Hell

In one of the most hostile environments on planet Earth, life perseveres. Immense pressure, frigid temperatures, and geysers of incredibly hot fluid define this seemingly-inhospitable environment at the bottom of the world’s deepest ocean trench. How do researchers study such an ecosystem, and what could possibly survive in a biosphere like that? While getting there is far from easy, the abundance of life is truly amazing.

Flooring Facts And Figures

The Mariana Trench is the deepest ocean trench and the lowest point on the surface of the Earth, 7,000 feet lower than Mount Everest would reach if you turned it on its head. The bottom of the trench is 36,000 feet below sea level, where the last rays of light faded entirely from view some 23,000 feet above. The water down in the Challenger Deep lingers near freezing all year-round.

Google Maps

In the Mariana Trench, the water is a brisk 34 degrees Fahrenheit, and the pressure of all that water is enough to crush a human being in an instant. The only sources of warmth are hydrothermal vents, which spew superheated water and minerals as the ocean meets the magma seeping up from the mantle below. These vents can reach temperatures of 750 degrees Fahrenheit, but the water cannot boil because of the incredible pressure.

Strange Creatures Of The Deep

Anything living down in the depths of the Mariana Trench must be able to withstand the extremes. Millions of years of evolution have led to the development of many strange-looking creatures that dwell in the inky blackness of the depths below the abyss. Among those creatures are fish, like the frilled shark and the deep sea hatchetfish, which make up some of the deep ocean’s frighteningly toothy predators. The frilled shark has a pale, eel-like body with a flexible skeleton and two rows of widely-spaced, needle-like teeth. While it is creepy-looking, it seems relatively normal when compared to the hatchetfish, whose body is much taller than it is wide. The incredible thing about the hatchetfish is its ability to produce its own glow, called bioluminescence, to match the amount of light filtering down from above, so that if viewed from below, it remains unseen.


Most of the creatures dwelling in the depths of the trench, however, are invertebrates. Tubeworms most famously make their homes alongside the boiling hot hydrothermal vents, feeding off of the mineral-rich liquid they spew. Another type of deep-sea worm that makes its home in the Mariana Trench is the zombie worm, which feeds off of animal detritus, including bones, by excreting acid that breaks down the food into easily-absorbable nutrients.

It’s Not All Bad

Not everything that lives at the bottom of the ocean is terrifying. Sea cucumbers are goofy little blobs that live on the ocean floor and eat plankton and whatever leftovers they can sweep up from the sand. Sea stars also make their home in the dark waters, feeling along the ground for anything good to eat. The fleshy, skeleton-less bodies of these little critters have no problem surviving in the chilly, high-pressure depths.

Finally, the cutest creatures you’ll find in the Challenger Deep is also one of the smallest. Members of the fantastic group of living things called extremophiles, tardigrades love the boiling-hot waters near hydrothermal vents. These little organisms often referred to as water bears can survive just about anywhere, including the vacuum of space. They are as resilient as they are adorable, and they don’t mind the weather down there one bit.

Check out these other strange creatures that live at the bottom of the world’s deepest trench.

Global Warming Could Spell The End For Sea Turtles

As global air and sea temperatures rise, numerous species are facing the consequences of our actions. Habitats are disappearing, climate change is shifting habitable zones, and some animals just can’t take the heat. Among the sea turtle populations, scientists are observing an unusual and disturbing trend that could prove fatal in a matter of generations.

A Biology Lesson

Sea turtles are part of a group of reptiles whose biological sexes are determined by their environment. Specifically, sea turtle eggs are impacted by the temperature of the sand around them. If the sand is cool, the eggs hatch as males. If the sand is warm, the eggs hatch as females. Rising temperatures had scientists wondering if more heated sands might mean that slightly more females were hatching. To find out, they traveled to a major sea turtle breeding ground near the Australian coast.

When they arrived, the marine biologists set out to determine the sexes of the sea turtles that had returned to their breeding grounds to lay eggs. Blood tests and laparoscopic observations helped the scientists count and catalog the number of females and males present on the breeding grounds. Their findings were undoubtedly fascinating, confirming their suspicions, but more than that, they also established the scientists’ greatest fears. Not only had the number of female turtles risen with the increase in temperature, but the males had become outnumbered 116 to 1.

The Undeniable Truth

Raine Island, one of the major breeding beaches in the Coral Sea area, is a point of significant concern for scientists. The rookery is nesting grounds for up to 200,000 turtles, with 18,000 coming to nest at any given time during peak season. With such a high output, maintaining gender diversity is important, which is why what the scientists found was so alarming. Based on their analysis, Raine Island has been producing almost exclusively female offspring for nearly 20 years. The ratio of females to males has been increasing since the 1970s and 80s, though the numbers were closer to 6 to 1 back then.

As the sea temperatures rise, the coral bleaches and the sand grows ever warmer, scientists worry that the outlook may be grim for these massive turtles. But, all is not lost. At another breeding ground near Brisbane, farther south where the temperatures are cooler, the female turtles only outnumber the males by a factor of two-to-one. The difference between the two rookeries confirmed for the scientists that climate change was playing a significant role in the female-favoring shift.

A Worldwide Perspective

Studies of breeding grounds across the world indicate that the global average is shifting noticeably in favor of females, with a roughly 3 to 1 average ratio. Having the numbers slightly skewed toward females might not be all bad, as long as the bias remains relatively small. Male turtles can mate with multiple females, which continues to work out just fine when there are a few more ladies around than there are gents. However, as the temperatures climb, scientists fear that the variation might become more noticeable as it has on Raine Island.

Although sea turtles have been around for thousands of years, the temperature fluctuations in the past have been gradual. Present-day turtles are seeing climate swings throughout single-lifetimes as opposed to generations. The oceans 50 years ago were cooler and cleaner than they are today. In coming decades, we may witness the extinction of some endangered species of turtles as their breeding grounds warm and skew their gender ratios. With any luck, the turtles will migrate to cooler waters and save themselves.

Other than these all-female turtle births, there have been a lot of other really strange things happening in our oceans lately…

A 512 Year-Old Shark Is The Oldest Living Vertebrate On The Planet

Greenland sharks are among some of the longest-lived vertebrates on the planet, with lifespans ranging from 300 to 500 years. Scientists studying these sharks in their native waters of the North Atlantic Ocean have recently found a specimen who is estimated to be 512 years-old. By comparison, the oldest known Galapagos Tortoise, a species often referred to for their longevity, lived to be only 152 years old.

The Key To A Long Life

What makes these giants live such long lives? Part of their longevity is believed to come from their slow metabolisms. Larger animals, like whales and elephants, tend to have longer lifespans due to slower metabolisms. Smaller animals, such as parrots, also tend to live longer, leading us to conclude that size isn’t all that matters.

For Greenland sharks, their habitat has a significant effect on their metabolisms. The icy waters of the North Atlantic mean lower body temperatures and a need for more efficient energy use. As a result, their bodies age more slowly, extending their lifespans.

Late Bloomers

A side-effect of their long lifespans is their lengthy growth cycle. Greenland sharks don’t reach adulthood until they are 100 years old, which means that they cannot produce offspring until they have survived for at least a century.

The sharks grow 0.4 inches per year up to their full-grown length of 21 to 24 feet. As fully-matured adults, Greenland sharks weigh in at anywhere from 2,200 to 3,100 pounds. On average, scientists have observed these giants to be between 8 and 15 feet long and about 880 pounds.

A Bizarre Delicacy

One of the Greenland shark’s adaptations for survival makes their meat inedible without the right processing. Their bodies contain high concentrations of trimethylamine oxide and urea. The former is what makes it toxic, and the latter gives it an unpleasant, urine-like odor. When consumed in small amounts, trimethylamine oxide produces effects similar to extreme drunkenness. Dogs that have eaten unprocessed shark meat are unable to stand or walk until their bodies process the toxin.

As a precaution, when humans prepare the flesh, they often bury it in the ground for anywhere from six to eight weeks to press out the chemical before digging it up and hanging it to dry for several more months. Even then, the smell of urea persists, and that odor has given rise to many origin stories and legends in local folklore.

A Species Steeped In Legend

According to an Inuit creation story, a woman washed her hair in urine and dried it with a cloth that blew into the ocean to create Skalugsuak, the first Greenland shark. A different story from the same culture says that different sea creatures were created from the severed fingers of a drowned girl, one of which was Skalugsuak. The Igloolik Inuit believe Greenland shark flesh to be an aid to their shamans. In their cosmology, the Greenland shark lives in the urine pot of their goddess of the sea, Sedna, and that is why its flesh smells so strongly.


While its place in legend has been set for centuries, as it doubtless will for centuries, the Greenland shark’s mark in the history books is freshly made. Outlived only by immortal jellyfish, the ancient sharks continue to awe and intrigue marine biologists and geneticists alike as we search for the keys to human longevity.

MORE: These microbes at the bottom of the sea teeter on the edge of life and death, and can live for thousands, maybe even millions of years with almost no energy.

Scientists Discover A New Fish So Beautiful They Named If After Aphrodite

A team of researchers from The California Academy of Sciences recently discovered a new fish so beautiful that they named it after Aphrodite, the Greek goddess of love and beauty. Due to modern advances in scuba gear and submersibles, marine scientists have been able to explore areas never before accessible. The discovery of Tosanoides Aphrodite was made by Luiz Rocha and Hudson Pinheiro while diving around St. Paul’s Rocks, about 600 miles off the coast of Brazil. The brightly colored fish was found in what’s known as the ocean’s “twilight zone,” a region of darkness located 200-500 ft. below the surface of the waves.

Destined To Find Fame For Its Beauty

“This is one of the most beautiful fishes I’ve ever seen,” said Dr Luiz Rocha, the Academy’s Curator of Fishes. “It was so enchanting it made us ignore everything around it.”

Luiz Rocha/California Academy of Sciences

A video camera along for the expedition proved Rocha’s statement truer than he may have known at the time. So enthralled were the divers with the sight of the new fish that they didn’t notice that a 10-foot long sixgill shark was circling right above them. Luckily, although sixgill sharks often come into contact with divers, they tend to be more curious than dangerous.

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A Whole New Genus?

The 3-inch long T. Aphrodite sports bright pink and yellow neon colors and almost appears to have been decorated with highlighters. Though this may seem like a risky appearance when it comes to would-be predators, Pinheiro explained that pink and red are common colors of deep sea fish. This is due to the fact that red light doesn’t penetrate as deep as they tend to live beneath the waves. Thus, fish of these colors would generally be invisible to any predator who doesn’t happen to be carrying a flashlight.

Luiz Rocha/California Academy of Sciences

Rocha and Pinheiro were not only able to capture the fish on camera but collect several of them to study more closely at their lab in San Francisco. They reported that male members of the T. Aphrodite species tend to be yellow and pink in color, while the females stick to a solid reddish orange appearance.

It was during genetic analysis that the team determined the fish to belong to a genus known as Tosanoides. This raised several questions, as this group of fish has previously only been known to reside in the Pacific Ocean. It may even suggest the possibility that the fish could be a part of a whole new genus entirely, but in order to prove such a speculation, the team says further genetic analyses will have to be done.

Famous Family Members

The team also revealed that the T. Aphrodite appears to have a relative who was also named after a famous figure. Genetically, it appears to be most closely related to a Hawaiian fish called Tosanoides Obama, who derives its name from the U.S. President.

R. L. Pyle

Though they admit that exploration of oceanic twilight zones isn’t always easy, the team appears enthusiastic about continuing exploration of such areas. “In a time of global crisis for coral reefs, learning more about unexplored reef habitats and their colorful residents is critical to our understanding of how to protect them,” Dr. Rocha said. “We aim to highlight the ocean’s vast and unexplored wonders and inspire a new generation of sustainability champions.”