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Barrel jellyfish

Rhizostoma pulmo

Photo: Barrel jellyfish
State of endangerment
Non Endangered
Animal description
The Barrel Jellyfish, scientifically known as Rhizostoma pulmo, is a captivating marine creature that belongs to the phylum Cnidaria, a group known for their stunning yet potentially perilous jellyfish species. This particular species is one of the largest jellyfish found in the seas around the United Kingdom and throughout the northeast Atlantic, as well as in the Mediterranean Sea, making it a significant subject of interest for marine biologists and ocean enthusiasts alike.

Characterized by its large, translucent, and barrel-shaped bell that can reach up to 90 cm in diameter, the Barrel Jellyfish is an imposing presence in the waters it inhabits. The bell's bluish or yellowish shade, coupled with its frilly appearance, adds to the creature's mesmerizing beauty. Underneath the bell, eight thick, fringed arms extend downwards, which are used for feeding. Unlike many jellyfish that have stinging tentacles, the Barrel Jellyfish's arms are equipped with small, sticky appendages that capture plankton and small fish, which are then maneuvered towards the jellyfish's mouth for consumption.

One of the most fascinating aspects of the Barrel Jellyfish is its lifecycle, which includes both sexual and asexual phases. The adult jellyfish, known as the medusa, is typically seen in coastal waters during the spring and summer months when they come closer to shore to breed. After spawning, the fertilized eggs develop into larvae which eventually settle on the seabed and morph into polyps. These polyps can reproduce asexually, budding off new jellyfish that will grow into the medusa form, thus continuing the cycle of life.

The Barrel Jellyfish plays a vital role in the marine ecosystem. As a predator of plankton and small fish, it helps to maintain the balance of marine life in its habitat. Moreover, it serves as a source of food for a variety of marine creatures, including the Leatherback Turtle, which feeds almost exclusively on jellyfish.

Despite their size and impressive appearance, Barrel Jellyfish are considered to be of minimal threat to humans. Their sting is not powerful enough to cause serious harm, making them relatively safe to observe up close, compared to other more dangerous jellyfish species. This, combined with their majestic appearance, makes them a popular subject for underwater photography and marine observation.

In conclusion, the Barrel Jellyfish is a remarkable marine species, known for its significant size, unique feeding mechanisms, and crucial role in the oceanic ecosystem. Its presence in the waters serves as a reminder of the diversity and complexity of life beneath the waves, and the importance of preserving these delicate marine habitats for future generations to explore and understand.
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