Comb jellies (Ctenophores) are marine invertebrates often mistaken for true jellyfish due to their delicate, transparent appearance. The direct answer to whether they sting is no. The absence of a stinging mechanism is a fundamental biological difference that sets them apart from their stinging counterparts.
The Reason Comb Jellies Do Not Sting
Comb jellies pose no threat to humans because they completely lack the specialized stinging cells found in true jellyfish. These stinging cells, called nematocysts, are microscopic, venom-filled capsules that true jellyfish (Cnidarians) use to inject toxins into their prey. When triggered, a nematocyst rapidly fires a harpoon-like filament to deliver a painful sting.
Ctenophores belong to the separate Phylum Ctenophora and simply do not possess this biological apparatus. Their evolutionary path diverged long ago from stinging jellyfish, resulting in a fundamentally different body plan for defense and predation. While harmless, their delicate, water-filled bodies are extremely fragile and break apart easily when removed from the water.
How Comb Jellies Capture Food
Since they lack stinging cells, comb jellies employ a unique hunting strategy using specialized, sticky cells called colloblasts. These cells are densely packed along the tentacles of many species, acting like microscopic fishing lines.
Colloblasts are complex structures consisting of a coiled spiral filament and a head containing numerous adhesive granules. When small prey, such as plankton or larvae, brushes against a tentacle, the colloblast head ruptures. This releases a sticky, mucoid substance, causing the prey to instantly adhere to the tentacle.
The coiled filament acts as a shock absorber, preventing the prey from tearing free as the comb jelly reels it in toward its mouth. This adhesive mechanism is highly effective for capturing small organisms but is harmless to human skin.
Telling Comb Jellies Apart from True Jellyfish
Comb jellies (Phylum Ctenophora) and true jellyfish (Phylum Cnidaria) belong to two distinct phyla despite their similar gelatinous bodies. The most obvious visual difference is the comb jelly’s characteristic locomotion system, which gives the animal its common name.
Comb jellies possess eight rows of fused cilia, known as ctenes or “comb rows,” that run vertically along their bodies. These ctenes beat in a coordinated, wave-like pattern to propel the animal through the water. This makes them the largest animals to rely on cilia for movement. As the ctenes move, they refract light, creating a shimmering, rainbow-like effect often mistaken for bioluminescence.
True jellyfish move by rhythmically contracting the muscles around their bell-shaped body. Their tentacles are armed with stinging nematocysts, while the tentacles of comb jellies, if present, are armed only with non-stinging colloblasts.