Communication of Jellyfish in the Natural World

Communication of Jellyfish in the Natural World

        “Sting” is the first word that comes to mind when one thinks of this animal. Of the many creatures in the sea that marine biologist study, the jellyfish still seems to be a mystery to the general public. They are a diverse and unique species that has a fascinating way of life. Jellyfish are invertebrates and belong to the phylum Cnidaria along with sea anemones and coral (General Biology Laboratory Manual). These creatures display radial symmetry and are composed mainly of water, about 95%-97%, and of protein, about 3%. Jellyfish are very unique in that they do not posses eyes, a heart, or a brain. Instead, they have a nervous system, or a nerve net, that is made up of receptors that can detect stimuli such as light and odor. Depending on the type of jellyfish, some have ocelli, a substitution for eyes. Occelli are spots found around the rim of the jellyfish that are sensitive to and can see light but are unable to see shapes. These animals also contain sensory organs called rhopalia, which help in maintaining its balance (Gambino, 2012). Of all the unique facts about jellyfish, one seems to stand out from the rest; that it, how it is able to communicate with its prey, predators, competitors and potential mates. Because of its unique characteristics, jellyfish have adapted to the world in which they live to communicate with the natural world in a much more effective way than other marine animals, which is better suited for their way of life.

        Jellyfish are very unique in that they are able to reproduce both asexually and sexually (Lucas, 2001). The transformation of a jellyfish from an egg to an adult is a tedious process that takes several months. The process begins with an adult jellyfish, or medusa, releasing sperm into the water. A female does the same with an egg and the two join to form a planula. The planula swims until it finds a surface, such as a hard rock or other stable object to attach to. The planula turns in to a polyp and begins to reproduce asexually, creating clones of itself (Hiler, 1998). This process is known as strobilation, where the polyp begins to elongate and segment (Hoekenga). As the strobilation continues, each segments separates and becomes an ephyra, which grows into an adult medusa or jellyfish (Hiler, 1998). The reproduction of jellyfish generally does not involve the picking and choosing of mates. The male will release his sperm into the water as will the female and that generally completes the interaction between the two. This concept is known as mass spawning and allows for jellyfish to mate without having any interactions or contact with each other. For most jellyfish, this is true, but a specific species of jellyfish has been identified to engage in a courtship ritual (Hoekenga).

A species of jellyfish known as the Copula sivickisi has developed quite an intricate mating ritual. When these jellyfish mate, the male would take a hold of the female’s tentacle and pull her around in the water. Because jellyfish have a manubrium, a tube that serves as a mouth, anus and reproductive channel, the male will begin to pull the female close until their manubria are touching and deposit his bundle of sperm onto one of her tentacles. The female then ingests the sperm and fertilized the eggs she is carrying. After a few days, the female produces an embryo strand, which grows to form many polyp, which eventually become adult medusa (Hoekenga). For most jellyfish, communication and interaction are not an important factor amongst potential mates, but for Copula sivickisi and other jellyfish species similar to it, courtship rituals and their unique way of mating are how they communicate with potential mates and the natural world.

Another way in which jellyfish are unique is in the way they communicate with their prey, predators, and competitors. When it comes to getting resources, jellyfish have a great advantage with the use of nematocysts or stinging cells. When the jellyfish detect that something is touching their tentacles, poison is ejected and the jellyfish is able to catch its prey or attack a predator or competitor. Because jellyfish really have no internal organs, digestion is unique for them. Organs such as the liver or pancreas are important for a human to digest food but because the jellyfish doesn’t produce much waste, the waste that it does produce passes through their large mouth. In fact, for animals like the jellyfish, keeping waste products makes them heavier so jellyfish tend to digest their food as well as pass their food rather quickly (O’Connor, 2011).  Its stinging cells allow it to be a strong competitor against many other creatures, even those of a larger size (Hiler, 1998). The Jellyfish’s main form of prey is zooplankton and eggs and larvae of fish, which is a common diet for other animals such as fish. Fish make up a large sum of the jellyfish’s competitors for resources such as food. Because jellyfish have these poisonous stinging cells, they are able to use their tentacles to sting a competing fish and win the resources (Purcell, 1999). The more resources a jellyfish has access to, the better equipped they are to continue to reproduce and survive. Testing the biomass of jellyfish suggests that they play an important role as the predator and have a large impact on their prey, mainly zooplankton and fish (Brodeur, Hunt, and Sugisaki, 2002). It has been studied that jellyfish and zooplanktivorous fish tend to compete for the same food and have similar diets that overlap with those of forage fish species (Purcell, 2003). Jellyfish may not be as fast as their competitors but it has its way of getting around. Instead of using fins it saves energy by utilizing the current to take it to its prey. When something triggers its stinging cells, the jellyfish goes in for the kill. Lucky for the jellyfish, they do not eat a lot so they are able to endure months of starvation if need be. A jellyfish’s ability to communicate and capture its prey is key to its survival. Without the use of its nematocysts, jellyfish would not be thriving and surviving in the way they are today (O’Connor, 2011).