Jellyfish Blooms

Jellyfish are becoming more common in the Marmara Sea—and it’s not just a coincidence. As sea temperatures rise and fish populations drop due to overfishing, jellyfish are thriving in the gaps left behind.

With fewer predators and more plankton to eat, they’ve begun to bloom in record numbers, especially near coasts. Jellyfish are made up of 95% water and have no true stomach, relying on a simple cavity to absorb food.

While they may seem harmless, large jellyfish swarms can disrupt fishing, sting swimmers, and signal deeper imbalances in the sea. Their growing presence tells a story: when ecosystems shift, new ones form—often in unexpected ways.

Jellyfish to Look Out For

Aurelia aurita (Moon Jellyfish)
The most common species in the Marmara Sea. Mostly harmless. Feeds on plankton and tiny marine organisms.

Chrysaora hysoscella (Compass Jellyfish)
⚠️ Venomous. Known for painful stings that can harm both humans and wildlife. Often sheds its tentacles after stinging.

Rhizostoma pulmo (Barrel Jellyfish)
⚠️ Venomous to the touch. Large but slow-moving. Common in summer. Often used as shelter by small fish.

Rhopilema nomadica (Nomad Jellyfish)
⚠️ Venomous. Known to migrate from warmer waters. Becoming more common due to climate change.

Liriope tetraphylla (Liriope Jellyfish)
Small, transparent jellyfish found in warmer coastal areas.

Moon Jellyfish

About Moon Jellyfish

Shape: A round, transparent body with four faint, horseshoe-shaped rings in the center.

Color: Clear to pale pink or light purple.

Size: Medium—usually palm-sized, but can grow larger.

Notes: Moves gently with short, frilly tentacles. Harmless to touch.

Comb Jellyfish

Mnemiopsis leidyi (Sea Walnut)
An invasive species that preys on zooplankton and fish eggs. Harmful to fish populations, especially anchovies.

Beroe ovata
Predator of other comb jellies. Helps control Mnemiopsis populations. Believed to have arrived via ballast water.

Pleurobrachia pileus (Sea Gooseberry)
Small and harmless. Uses sticky tentacles to capture tiny plankton.

Sea Walnut

About Sea Walnut

Shape: Oval, translucent body with rows of shimmering, rainbow-like cilia.

Color: Clear with light-reflecting combs.

Size: Around 5–10 cm.

Notes: Not a true jellyfish. No sting. Harmless to humans.

Visual and scientific references adapted from research published by various marine science platforms.
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