These jellyfish are remarkable for several reasons. The first is that they live at incredible depths, up to 4,800 feet below the surface. They are also rarely seen by human beings. Their scientific name, Tiburonia granrojo, comes from the MBARI’s ROV Tiburon, according to Smithsonian. The jellyfish was only discovered in 2003.


This large jellyfish can grow to be over three feet in diameter. These jellyfish are rarely seen due to the depths that they live at, but they are described as having four-seven arms, setting them apart from most jellyfish that have tentacles. They are used for retrieving prey. These fleshy, oral arms are long are tinted red, as is the jellyfish’s bell. That is the large, round head-like shape that most will associate with jellyfish. 

Although the jellyfish is rarely seen or studied, it’s believed to be similar to other jellyfish in some fundamental ways. For example, scientists believe it doesn’t have a heart, bones, eyes, or even a brain. It’s composed mostly of water. 

Detail shot of Granrojo Jellyfish arms
Detail shot of Granrojo Jellyfish arms


Throughout the history of the species, only twenty-three members have ever been observed by humans. One of these was quite small, at only six inches. They are believed to live off the coast of North America, Baja, Hawaii, and Japan. But, because of the depths that they live at, around 2,000 to 4,800 feet, they are rarely seen and could live in other parts of the world’s oceans. Some scientists believe that these jellyfish can handle different temperatures of water, conformable in cool and warm waters. 

One specimen of the species was obtained and placed in the National Science Museum in Tokyo, but, like most deep-dwelling species, it’s unlikely that easily capture and upkeep of these creatures is going to be possible. 

The fact that these jellyfish live so deep beneath the ocean’s surface allows them some production from the threats that plague other jellyfish species, such as trawling (resulting in bycatch), the immediate effects of pollution, and coastal erosion. The depth they spend most of their lives is rarely visited by human beings. 


It’s believed that these unusual jellyfish use their four-seven arms as a way to catch and consume prey. They are also considered to be avid hunters, moving easily after their prey. Their diet is likely similar to that of other jellyfish. They mostly likely eat small fish and zooplankton that they’re able to capture with their tentacles.

 Some scientists have considered whether or not the ”big red” jellyfish can use their arms, as other jellyfish use their tentacles to entangle and sting their prey. 


These jellyfish likely reproduce in the same or in a similar way to other jellyfish. That is, through several different stages. They release Superman’s egg into the water which forms a planula. This planula hooks to the bottom of a rock or some other structure and grows into a polyp. This stage lasts for a number of months or even years. Now, the polyp uses asexual reproduction, cloning itself into an ephyra. This grows into an adult jellyfish, according to Scientific America. 

Granrojo Jellyfish in the deep ocean
Granrojo Jellyfish in the deep ocean

Scientists have assumed that these jellyfish live similarly short lives to other species of jellyfish. Generally, they live between two and six months. 


Due to the fact that these jellyfish live deep within the ocean’s waters, they are subject to few threats. Human fishing practices are unlikely to reach this deep, nor are the immediate effects of pollution and coastal erosion. Climate change is always something to be concerned about, but the depth at which these creatures live affords them some protection. 

Despite this, they are likely always at threat from other marine creatures that may choose the “big red” as a source of food. 

Facts About the Granrojo Jellyfish

  • The Granrojo jellyfish lives up to 4,800 feet below the ocean’s surface. 
  • Little is known about the Granrojo jellyfish’s life and habits. 
  • The Granrojo jellyfish is one of the largest jellyfish in the Earth’s oceans. 
  • The Granrojo jellyfish is a deep red color, leading to its nickname, “Big Red.” 
  • Scientists assume that the Granrojo jellyfish is similar in its diet and reproductive habits to other jellies. 


How big is the Granrojo jellyfish?

This jellyfish usually grows between two to three feet. But only a few specimens have been seen by human beings. This means that there could be bigger “big red” jellies out there. 

Where do big red jellyfish live?

They live deep beneath the ocean’s surface and are known to reside in the Pacific Ocean. But it’s likely they live elsewhere as well. 

What is the rarest jellyfish?

The lion’s mane jellyfish is often considered to be the rarest jellyfish in the world. But, any that live in the ocean’s depths are rarely seen and certainly do not feature prominently in the world’s aquariums. 

What is the largest jellyfish?

The lion’s mane jellyfish is often considered to be the world’s largest jellyfish. It can grow to a massive seven feet in diameter. But, most specimens are slightly smaller than this, around six-six and a half feet. They take their name from the hair-like tentacles they feature. 

What is a cosmic jellyfish?

A cosmic jellyfish is a jelly that resembles a UFO. It was discovered while exploring the Utu Seamount in the National Marine Sanctuary of American Samoa, according to NOAA. 

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