Comb Jellyfish
Information About the Comb Jellyfish
Comb jellyfish, despite the name, are not a jellyfish at all. Jellyfish are a part of the Cnidaria family, while comb jellyfish are part of the Ctenophora, in Greek this literally means comb bearer. Jellyfish are well known around the world, but comb jellyfish are not as well known. One reason that people are more likely to know about the jellyfish, is that it has a stinger and there are many people that are stung while swimming in the ocean each year. Comb jellyfish, however, do not have a stinger.
In other ways, there are similarities between the jellyfish and the comb jellyfish. They are both translucent invertebrates, and they both are generally free floating in the ocean. Comb jellyfish do have some brilliant colors, generally there are eight “stripes” of bright color. These colors are along the comb rows. There are eight comb rows that extend from the end of the comb jellyfish that is opposite its mouth.
The comb rows are used to vibrate the water which can then propel and steer the jelly. More importantly, the comb rows create a current that forces water and food continuously into its mouth. The comb rows will also glow a very soft green color if the jelly is disturbed at night. These fish are a multi-cellular animal that do have some internal organs. They have an internal cavity, a mouth, and anal pores. Most types of the comb jellyfish usually only grow to about four inches in size, much like a large orange.
They are difficult to study because their bodies will break apart if they are taken out of water. That is one reason why little is known about them. Despite their ability to thrive, they are very sensitive to chemicals in the water. This sensitivity is vital to the fish’s ability to find food, but it does make the fish susceptible to environmental hazards.
This invertebrate prefers open waters, just like the jellyfish, and during rough seas it will tend to seek out deeper, calm water. It used to be found mainly in the North Atlantic Ocean, and in bays on the eastern seaboard, but it has now densely populated the Black Sea and has also been found in the Baltic and Caspian Seas, where they are also expected to become numerous. The fish was transferred to the Black Sea in ship ballast water. Ships use water loads to provide stability and balance when they are carrying low levels of cargo. When cargo is picked up at ports, the ships dump their ballast water. In this way, over ten billion tons of water is moved from port to port around the world every year.
In 1982, comb jellyfish were transferred from America to the Black Sea by ships dumping water in that region. The story from there is a classic tale of invasive species taking over the habitat of native species and damaging the environment. These fish are voracious predators and are carnivorous. They eat plankton, larvae, crustaceans, and even small fish. They have even been known to eat other species of comb jellyfish that are smaller in size.
They nearly decimated the Black Sea commercial fisheries business as they left local native fish and seafood without a food source. They have also reduced the oxygen levels in the Black Sea, which further has damaged other indigenous fish populations. Seafood, anchovy, and even dolphin numbers have been dramatically reduced since the introduction of the comb jellyfish to the area. By 1995, over 90 percent of the biomass of the Black Sea was made up of the comb jellyfish. The story for the Caspian and Baltic Seas appears to be much the same.