Jellyfish are fascinating creatures that have captivated the human imagination for centuries and they have inhabited the earth for far longer, It could be that they date back to before the dinosaurs.
Scientists have evidence these creatures could have been in the oceans as far back as 700 million years, the oldest fossils being discovered in Utah, when the entire U.S. West was under the Pacific Ocean.
More interestingly, unlike much other ocean life, they seem to be adjusting well to climate change. Jellyfish are multiplying in their droves, despite overfishing, ocean acidification and marine heat increases. However, this doesn’t mean they are bullet proof and experts are expecting to see upsets in their population figures due to the decrease in plankton, which is what jellyfish feed on .
Jellyfish, inappropriately named, are not fish at all and belong to the phylum Cnidaria, which also includes corals and sea anemones. These unique organisms are found in every ocean and come in a range of sizes and colors yet despite their beauty, jellyfish can be dangerous to humans and the environment.
The Jellyfish look
They are characterized by their bell-shaped or umbrella-shaped body which is made up of a transparent, gelatinous substance called mesoglea. This substance is made up of mostly water, along with some protein and polysaccharides.
Jellyfish have two basic body forms, the medusa and the polyp. The medusa is the familiar bell-shaped body form that most people associate with jellyfish. The polyp, on the other hand, is a cylindrical body form that is typically found in the early stages of the jellyfish life cycle.
The Jellyfish body
Jellyfish have no brain or central nervous system, but they do have a simple nervous system that helps them to detect and respond to their environment.
They also have a basic digestive system, with a single opening that serves as both the mouth and the anus, which must make for interesting flavors at meal-time.
From safe to dangerous Jellyfish.
Jellyfish come in a wide variety of shapes and sizes. Some, like the moon jellyfish (Aurelia aurita), are small and relatively harmless. Others, such as the box jellyfish (Chironex fleckeri), are much larger and can deliver a powerful sting that can be deadly to humans.
Like all ancient creatures, jellyfish have a number of adaptations that enable them to survive in their often-challenging environments. Many species have tentacles lined with stinging cells called nematocysts, which they use to capture prey and defend themselves from predators. Some species of jellyfish also have the ability to regrow lost body parts, including their tentacles.
Jellyfish play an important role in marine ecosystems. They are a source of food for a number of marine species, including sea turtles, sunfish, and some species of fish. They are also important predators of small planktonic organisms, and help to keep the ocean's food webs in balance.
Despite their importance in marine ecosystems, jellyfish can also be a nuisance to humans in certain contexts. Some species are known to form massive blooms or swarms, which can clog fishing nets, damage equipment, and even shut down power plants. In addition, some species of jellyfish are known to deliver powerful stings, which can cause severe pain, swelling, and even death in some cases.
In recent years, jellyfish blooms have become an increasing problem around the world. Scientists are still uncertain about why these blooms are occurring, but some possible factors include warmer ocean temperatures, pollution, and overfishing.