Jellyfish – Questions and Answers
What are jellyfish?
They are soft-bodied free-swimming aquatic animals with a gelatinous bell shaped body and trailing tentacles on the underside of their body. They move by contracting their bodies and do not have much control over where they go. Most jellyfish drift with the water currents and are made up of more than 90% water.
Jellyfish are not even actual fish. This is a bit of a misconception as they’re really just oversized zooplankton that freely float in the ocean currents. The confusion exists because they can be qualified as a plant, animal, and also categorised with sea anemones and coral.
Where are they found?
There are over 1000 species of jellyfish in the world that are living nearly everywhere in the ocean. Some species survive best in Arctic waters while others live in the warmer waters near the equator. The beauty about jellyfish is their ability to adapt and thrive wherever they are.
A polyp’s habitat is whatever it latches onto before maturing into an adult jellyfish (medusa). They form blooms that number in the thousand and the saltier the water, the larger the bloom. Jellies often use the current and their body to travel without expending energy. But even the tamest of currents can overwhelm them because of their lack of brain, blood, and central nervous system and fast currents can cause harm.
What do they look like?
There are many different types of jellyfish. Some just look like small, clear blobs, while others are bigger and more colourful with tentacles hanging beneath them. Jellyfish often look like a bell with tentacles all around the edge or hanging off the bottom.
What do they eat?
Jellyfish are not picky when it comes to eating and the free-floating ocean creatures are considered opportunist predators. The size of the jellyfish plays a large role on what they decide to capture and ingest. Smaller jellyfish may only eat eggs and plankton while larger species can consume larger prey or even other jellies.
How do they find you?
They don’t go looking for you, it’s usually we end up in their way! Jellyfish use their sting to capture prey and act as a defence mechanism. When their tentacles encounter a human or other sort of prey they reach out and fire out harpoon-like structures containing a neurotoxic venom. It will paralyse their prey but in the case of us lowly humans it will just really hurt.
How do they feed?
The process of capturing their prey is another way jellyfish are unique. By using their tentacles, they sting their prey into paralyzation or death. Often times the prey they kill are too large for them to even eat because as they float freely with only their sensory system, the size of what they are attempting to devour is unknown. Their mouth lies underneath their belly and can only fit so much. The size of their bell-shaped body is a giveaway as to how large their mouths are. Some jellyfish also will eat their own. The choice in food makes them more than simply opportunist but also cannibalistic.
How do they sting?
Each jellyfish tentacle is covered with thousands of cells called cnidoblasts, which house nematocysts containing stinging threads. When a jellyfish encounters another object, pressure inside the nematocyst causes the threads to uncoil. The stinging cells spring out at the unwitting victim like tiny darts, firing venom into it. The venom is a neurotoxin designed to paralyze jellyfish prey.
Although a jellyfish can kill a small aquatic animal, its sting is not usually fatal to humans. It tends to cause pain, skin rashes, fever and muscle cramps. The degree of pain and reaction to a jellyfish sting can depend on the species — larger jellyfish have larger cnidoblasts that can penetrate deeper into the skin, and some jellyfish have stronger venom than others.
What can I do if I’ve been stung?
When you’re at the beach, watch out for jellyfish both on the water and on the sand.
Even a tentacle that has been separated from its jellyfish can sting. If you do get stung, first remove any tentacles clinging to the skin.
Don’t wash the area with fresh water — it could release more venom into your body. Instead, clean it with rubbing alcohol or ammonia. Also, peeing on a jellyfish sting will not make it any less painful. So if a friend offers to help you can kindly tell them thanks but no thanks!
Any signs of an allergic reaction (shortness of breath, hives, wheezing) warrant immediate medical attention.
How can I stop myself from getting stung?
– Avoid areas populated by jellyfish. If at all possible, do not swim or spend time on the shore in areas known to be frequented by jellyfish. Choosing a lower-risk area is the easiest way to reduce your chances of being stung by a jellyfish. You can ask lifeguards, beach officials, or local residents if you are unsure whether or not jellyfish are a danger in a given area.
– Recognise risky conditions. Jellyfish may range near shore when there are strong winds. They can also appear in large numbers (known as a jellyfish blooms), so avoid the water when these occur.
– Heed warning signs. If you see a sign warning of jellyfish, it means that they have been spotted by officials. In areas were jellyfish are known to be a common threat, you may see permanent signs. Swim with caution in these areas, if at all.
– Watch for purple flags. At many beaches, officials will fly purple flags during times that jellyfish or other dangerous marine animals are present. If you see these flags flying, this is a signal to stay out of the water to avoid getting stung.
– Wear protective lotions. Some evidence shows that protective lotions such as Safe Sea may protect against jellyfish stings. Applying one of these lotions before you go in the water can be a good additional precaution.
