Box jellyfish
The box jellyfish, known scientifically as *Chironex fleckeri*, is a highly venomous marine creature commonly found in the waters of Australia and Southeast Asia. Recognized for its distinctive box-shaped body, which typically ranges from the size of a grapefruit to that of a basketball, this jellyfish is nearly transparent and difficult to detect in the water. It features approximately 60 long tentacles, which can reach lengths of up to 10 feet and are equipped with millions of stinging cells called nematocysts that deliver powerful venom. This venom is so potent that one sting can be fatal to humans, capable of killing an adult in as little as four minutes.
The box jellyfish primarily feeds on plankton, small fish, and shrimp, relying on its tentacles to capture prey rather than actively hunting. During the late summer, it spawns in river mouths and estuaries, with adults releasing eggs and sperm before dying shortly thereafter. The resulting larvae develop into polyps that can clone themselves and eventually transform back into jellyfish. To mitigate risks posed by box jellyfish stings, swimmers are advised to adhere to safety warnings and wear protective clothing. Despite their frightening reputation, the box jellyfish plays a crucial role in its ecosystem and has a relatively short lifespan of less than a year.
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Box jellyfish
The box jellyfish has a box-shaped body commonly the size of a grapefruit, but it may be as large as a basketball. The poison in its tentacles makes it the deadliest creature in the world.
Kingdom: Animalia
Phylum: Cnidaria
Class: Subozoa
Order: Chirodropida
Family: Chirodropidae
Genus: Chironex
Species: Fleckeri
The box jellyfish can be found in the waters of Australia and Southeast Asia. They are mainly found in bodies of salt water but have been found inland, in fresh water rivers and channels, when spawning.
The box jellyfish is named for its box-shaped body. It is commonly the size of a grapefruit, but it may reach the size of a basketball. Its body, called a bell, is nearly translucentor clearand is about 95 percent water. This makes it very difficult to see in the water. From the bottom of the bell dangle about 60 tentacles. Each of a large jellyfish's tentacles may be up to 10 feet (3 meters) long. The mouth and 24 eyes are in the center of the bell. Food caught in the tentacles is pulled toward the mouth, transferred to an attachment called an oral arm or pendulum, and passed into the mouth.
Swimmers and surfers in the ocean along Australia's northern coast and the coasts of southeast Asian countries have long known and feared the box jellyfishcommonly called the marine stinger or sea wasp. This jellyfish species is the most venomousor poisonouscreature known in the world. One adult box jellyfish has enough venom to kill 60 adult humans, and one sting is enough to kill a human. Some stings may be treated with antivenom and lotions, but a severe and untreated sting can quickly causes breathing difficulties as the venom travels through the body's systems to the heart. Death may come within four minutes of being stung. If the victim survives, they may be scarred with red welts for life. It is thought that the box jellyfish needs to be so poisonous because prey would damage the jellyfish's delicate tentacles and body if the prey were to struggle.
The diet of the box jellyfish includes plankton, small fish, and prawns, or shrimp-like crustaceans. Its favorite food is shrimp. The box jellyfish does not attack its prey, but it waits for prey to swim into its tentacles. Each tentacle is filled with millions of stinging cells called nematocysts. Each nematocyst acts like a tiny poison gun. When animals or people brush into the tentacles, chemicals on their skin cause the nematocysts to cock and fire. The nematocysts shoot and pierce the skin with tiny darts and inject poisons. The poisons instantly paralyze and kill small prey and cause extreme pain and quick death in larger prey and people.
Late in summer, adults swim into the mouths of rivers and estuaries, or waters where rivers and tides meet. The adults spawn, or release eggs and sperm into the water. Shortly after spawning, the adults die. The eggs and sperm mix and develop into planulae, which settle to the bottom of the river or estuary. The planulae then develop into polyps. Polyps look like stalks with tentacles. Colonies of polyps attach themselves to the undersides of rocks. The polyps reproduce without mating and shed little arm-like polyps called buds from their bodies. The buds and polyps change into box-like bodies with tentacles. In spring they detach themselves from the rocks to migrate to the sea. In the final stage of growth they become adults and are called medusae.
People may protect themselves from this dangerous creature by following warnings not to swim outside areas protected by special nets and by wearing protective clothing, such as lycra suits.
The average lifespan of the box jellyfish is less than a year, as they die shortly after spawning.
Bibliography
Schmidt, Timothy. “Chironex Fleckeri.” Animal Diversity Web, animaldiversity.org/accounts/Chironex‗fleckeri/. Accessed 29 Mar. 2024.
“What Is the Most Venomous Marine Animal?” National Ocean Service, National Oceanic and Atmospheric Administration, 1 June 2013, oceanservice.noaa.gov/facts/box-jellyfish.html. Accessed 29 Mar. 2024.