Sea Nettle (Chrysaora) is one of the genus of Scyphozoa class of the phylum Cnidaria. The species of sea nettle we are most commonly knowledgeable about are Chrysaora quinquecirrha, which is mostly found along the east coast of North America in the Atlantic Ocean, and Chrysaora fuscescens, which is mostly found along the west coast of North America in the Northeast Pacific Ocean.
The Sea Nettle is semi-transparent and has small whitish dots and reddish-brown stripes. In some cases, these stripes and dots are missing, and they make the sea nettle look whitish and opaque. The sea nettle is saucer-like in shape. The bell of the sea nettle usually grows to about 6 to 8 inches in diameter. It also has four oral arms attached to the underside of the mouth. In addition to this, it has a number of long tentacles, along the margins of its body, which extend for several feet.
Sea Nettles are equipped with a number of nematocysts along their oral arms and tentacles. These nematocysts are like capsules with a coiled thread inside it, which is lined with barbs along its length. The thread contains powerful paralyzing toxins within itself. When a sea nettle comes in contact with any hard surface and pressure is applied to the tentacles, these nematocysts get activated and the thread starts uncoiling. They get fired into the surface in its contact and inject their powerful venom into it.