The Jellyfish is Plankton
Floating with the currents
Jellyfish are fascinating marine animals classified as plankton. Despite their ability to swim, they cannot resist ocean currents, rendering them drifters in the vast seas.
The term "plankton" originates from the Greek word planktos, meaning wandering or unstable.
Why do they wash ashore?
The proliferation of jellyfish, such as the Pelagia noctiluca, on Mediterranean coasts is often attributed to strong south-easterly winds. These winds push them towards shores, as jellyfish lack the strength to counter the wind's force.
Jellyfish are Made of Water
98% water composition
Jellyfish are primarily water, making up 98% of their composition, which gives them their gelatinous texture and buoyancy. Their umbrella-shaped bodies allow them to move by rhythmically contracting and pushing water.
Biotechnological importance
These creatures are a boon to biotechnology. The collagen found in certain jellyfish species, such as Rhizostoma pulmo, is being studied for applications in artificial skin for burn victims and cosmetic products.
Jellyfish 101 | Nat Geo Wild
Video by Nat Geo Animals
Coral is Their Cousin
Stinging relatives
Jellyfish belong to the cnidarian family, sharing lineage with corals and sea anemones. Their name stems from the Greek word knidè, meaning nettle. This group includes over 9,000 species, of which 1,500 are jellyfish.
Deadly species
Some jellyfish, like the Australian Chironex fleckeri, also known as the sea wasp, are deadly due to their potent venom.
Beware of Their Stings
Venomous defenses
Jellyfish are equipped with stinging cells called cnidocytes along their tentacles. These cells fire venomous harpoons upon contact, causing a burning sensation. Stranded jellyfish remain venomous, so handling them requires caution.
No Lungs, No Heart, No Brain
Ancient marine inhabitants
Jellyfish have existed for over 600 million years, with fossil evidence linking them to ancestors known as Ediacaria.
Unique anatomy
Jellyfish lack lungs, hearts, and brains. Instead, they rely on body walls for respiration. Despite their simplicity, they possess digestive systems, muscles, nerves, and sensory organs for detecting light and maintaining balance.
Complex Reproductive Cycles
Free-floating and fixed stages
Dear Lykkers! Jellyfish have intricate life cycles. Some species release eggs into open water for fertilization, while others alternate between fixed and free-floating stages.
Size and Habitat
From tiny to massive
Jellyfish range from barely visible species to giants like the Lion's Mane jellyfish (Cyanea capillata), which can have umbrellas over two meters in diameter and tentacles up to 50 meters long.
Ubiquitous presence
Jellyfish inhabit oceans worldwide, from surface waters to deep seas, and even freshwater environments.
Jellyfish: Predator and Prey
Efficient hunters
Jellyfish feed on plankton, fish eggs, and larvae.
Part of the food chain
They are preyed upon by species like tuna, sunfish, and leatherback turtles. Recent studies suggest an increasing number of marine animals may rely on jellyfish for sustenance due to the decline of other prey species.
The Rising Jellyfish Population
Why are they multiplying?
Several factors contribute to jellyfish overpopulation:
Overfishing of natural predators.
Increased zooplankton availability due to fewer small fish competitors.
Warmer oceans promoting their growth and reproduction.
Fertilizer pollution boosting their food sources.
Nobel Prize Connections
Breakthrough discoveries
In 1913, Charles Richet won the Nobel Prize in Medicine for research on anaphylaxis, partly inspired by jellyfish venom.
In 2008, researchers received the Nobel Prize in Chemistry for their work on green fluorescent protein from Aequorea victoria, a luminescent jellyfish, revolutionizing medical research.
