Big Pacific: Nomura’s jellyfish, the ocean’s drifter

From pages 97-99 in Big Pacific:

Another plus-sized Pacific denizen is Nomura’s jellyfish, a gargantuan grazer that spends most of its life adrift in the Yellow and East China Seas. Starting life as a pinhead-sized polyp, this peripatetic monster mushrooms rapidly — in less than a year — to 2 meters (6. feet) in diameter and more than 200 kilograms (440 pounds) in weight. To fuel this extraordinary growth — up to a 10 percent increase in size per day — the juvenile jellyfish feeds on tiny plankton particles through a mouth which measures just a millimeter (3/64th inch) across.

The ravenous appetite of the burgeoning jellyfish cannot be satisfied by one miniscule mouth, however, so as the invertebrate grows, it develops more mouths of the same size beneath its umbrella-shaped bell. Zooplankton, fish eggs and larvae are pushed up towards these mouthlets by the pulsating action of the jellyfish through the water and the movement of its grasping tentacles. An adult Nomura’s jellyfish is said to be able to filter an Olympic-sized swimming pool of plankton in this manner in a single day.

The Nomura’s jellyfish has no eyes or brain. It can only control its depth in the water.

Once limited to the Yellow Sea, the Nomura’s jellyfish is now regularly found in the Sea of Japan, where mass aggregations of the animal are causing a headache for local fishers. No one is sure why population explosions have been seen there in recent years, but scientists suspect they are linked to the rising sea temperatures associated with global warming. This could be exacerbating population outbreaks already attributed to nutrient build-ups arising from coastal and agricultural development, and to overfishing — the last because of the severe reduction in the numbers of fish species such as swordfish and tuna that prey on the jellyfish and thus help keep a check on their numbers.

Big Pacific: Passionate, Voracious, Mysterious, Violent
By Rebecca Tansley

The Pacific Ocean covers one-third of Earth’s surface—more than all of the planet’s landmasses combined. It contains half of the world’s water, hides its deepest places, and is home to some of the most dazzling creatures known to science. The companion book to the spectacular five-part series on PBS produced by Natural History New Zealand, Big Pacific breaks the boundaries between land and sea to present the Pacific Ocean and its inhabitants as you have never seen them before.

Illustrated in full color throughout, Big Pacific blends a wealth of stunning Ultra HD images with spellbinding storytelling to take you into a realm teeming with exotic life rarely witnessed up close—until now. The book is divided into four sections, each one focusing on an aspect of the Pacific. “Passionate Pacific” looks at the private lives of sea creatures, with topics ranging from the mating behaviors of great white sharks to the monogamy of wolf eels, while “Voracious Pacific” covers hunting and feeding. In “Mysterious Pacific,” you will be introduced to the Pacific’s more extraordinary creatures, like the pufferfish and firefly squid, and explore some of the region’s eerier locales, like the turtle tombs of Borneo and the skull caves of Papua New Guinea. “Violent Pacific” examines the effects of events like natural disasters on the development of the Pacific Ocean’s geography and the evolution of its marine life.

Providing an unparalleled look at a diverse range of species, locations, and natural phenomena, Big Pacific is truly an epic excursion to one of the world’s last great frontiers.

Learn more by watching Big Pacific, available to stream on PBS.


This post is part of a series, explore additional posts hereBig Pacific: The Galápagos Tortoise, a roaming reptile >>