Why Jellyfish May Become the “Cockroaches of the Sea”

jellyfish as cockroaches of the sea
Sea Nettle Jellies photo by Cherilyn Jose

While jellyfish (referred to as jellies for rest of this post since they are not “fish”) have been painted by public aquariums to be moving and floating masterpieces, the ocean itself has a different viewpoint on them. If the oceans keep getting polluted and overfished at their current rate, the ocean may soon teem with jellies and little else.

Pollution can be in the form of chemicals, like fertilizers and treated (or untreated in many parts of the world) sewage. Pollution can also be physical, like garbage. Plastic is particularly common, and all sorts of wildlife ingest it. The most well publicized plastic eaters include sea turtles who mistake not only plastic bags for jellies, but any plastic bits floating in the sea, and sea birds who have been found dead with enough plastic in their stomachs to die from starvation. With those predators dead, jellies take advantage of the increasing amount of plankton and they proliferate like crazy.

Plankton are the bottom layer of the food web. Overfishing takes out of the ocean the edible sized fish that eat plankton and other small bait fish. With their predator fish gone, plankton proliferate. Jellies love plankton, and they can easily outcompete any young fish for it. The young fish die without reproducing and therefore do not replace their parent’s generation. The seas would theoretically become empty of anything but jellies.

Off of Japan there has been a lot of overfishing, and Nomura’s jellyfish are increasing at an astonishing rate. They can grow to be 6.5 feet (2 meters) wide and weigh up to 450 pounds (220 kg)! Fishermen pull up nets with nothing but hundreds of jellyfish in them. Many nets break under the jellies massive collective weight, and one boat even capsized from them! The fishermen’s early strategy to get rid of them by slicing them up actually increased the jelly population due to the special asexual reproductive techniques of jellies. A future post will delve into this unique aspect of jellies.

Not all news relating to jellies is bad, as their tentacles have inspired scientists create a cancer detector. Scientists made a long DNA strand that mimics the sticky nature of jelly tentacles. In experiments, this long DNA strand was able to capture 80 percent of the leukemia cells (a kind cancer cell) in the blood used. For more on this, please visit “Jellyfish Inspire Cancer Detector” at the Huffington Post.

Please note that I was unable to write this post from the point-of-view of a jelly, as they do not have brains!

Eew, the Freshwater Eel and Why You Shouldn’t Eat Me!

Monterey Bay Aquarium's seafood watch
Freshwater Eel

Hi, I’m Eew, a freshwater eel. I got my name because, well, humans don’t seem to like eels very much. Maybe it’s because we’re slimy, long, and very snake-like. Maybe it’s because we have a mouth full of sharp teeth, and we open and close our mouths often so we can breathe. Honestly, I’m not that scary! I would keep your fingers out of crevices while visiting a coral reef because our first instinct is to bite. It’s not like we have any limbs to use on self-defense!

Want to know something funny? Even though we are called “freshwater” eels, we actually spend a portion of our lives in the ocean! Eel larvae (newborn eels) live in the ocean, and when large enough they enter estuaries (water in bays that is less salty than ocean seawater), and then finally to freshwater rivers. Adult eels enter the ocean to spawn, the opposite of salmon. Salmon leave the ocean to make the trek up rivers to spawn where they were born. There about 6 species of freshwater eels used in sushi, where it is called unagi.

I’m on the Monterey Bay Aquarium’s Seafood Watch red list, which means that you should not eat me! That is because the current freshwater eel fishery is not sustainable. About 90 percent of the eel consumed in the United States is farm-raised. While that sounds nice, it doesn’t take in account that young eels are captured from the wild to be raised in farms. These young eels are not allowed to grow up and reproduce, hence the unsustainable part of the fishery. Ugh, I would hate to live in such crowded quarters, with poop and disease everywhere! Besides, since eels are carnivores, farmed eels just end up eating wild caught fish anyways (which is very inefficient if you think about the farm animals humans raise to eat).

So, in short, please do not order unagi with your sushi! All of us freshwater eels thank you!

Please download Monterey Bay Aquarium’s Seafood Watch app for information on other seafood not to eat.

UPDATE: Maine’s (USA) eels are being illegally caught to supply Asian market. Read more in this Economist article

Terry the Pteropod on Ocean Acidification

Hello, my name is Terry and I’m a pteropod.  What exactly is a pteropod?  Well, I’m also called a sea butterfly and I have been described as a “coffee bean with wings.”  What I really am is a marine snail that is about the size of a lentil, which is less than half an inch long.  My terrestrial snail cousins have a hard shell on the outside and a soft body inside, while my shell is on my inside and my gelatinous goo is on the outside.

Why am I important?  Well if polar bears are the poster animals for the melting polar ice caps due to global warming, then I am the poster invertebrate for ocean acidificationOcean acidification is also due to global warming as a rise in ocean temperatures can cause seawater pH to drop and become more acidic.

So how does the ocean become more acidic?  Well the same carbon dioxide emissions that warm our atmosphere and cause global warming ultimately become absorbed by the oceans.  The oceans cover more than 70% of the planet.  Carbon dioxide dissolves in water and make it more acidic, like soda.  While the seawater in the ocean is not turning into Coke, a sprinkle here and there of acidic water can have devastating effects on ocean life.

Ocean acidification will directly affect me, my descendents, and my planktonic peers as my inner shell will dissolve as the water around me becomes more acidic. I will die. While I have a fairly short lifespan of a few months (to years if I escape being eaten!) to begin with, it is the new gap in the bottom of the food chain that will be troubling.  Fish won’t have anything to eat, and the larger animals that eat them will be hungry too.  Imagine if on land all the grass and insects suddenly got wiped out.  Then everything from birds, deer, and bears would be scrambling around for new food sources or face extinction.

So, what can you do to help?  What you are hopefully already doing to curb global warming: driving less, carpooling, taking public transportation, and exploring the use of alternative energies.  The 3 R’s help too: Reduce, Reuse and Recycle.  Also support efforts to create Marine Protected Areas around the globe.  Less than 1% of the oceans are protected versus 12% of land being protected. Don’t forget to spread the word, as we can all make a difference by being informed!

UPDATE DECEMBER 2012: Scientists have found that pteropods are being affected by ocean acidification now, as opposed to a previous prediction of 2038. Link to article here