Sea nettle
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| Sea nettle | ||||||||||||||
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| Chrysaora quinquecirrha Agassiaz, ? |
The stinging Sea nettle (Chrysaora quinquecirrha) is one species of jellyfish. It is a semi-transparent bell-shaped invertebrate with small, white dots and reddish-brown stripes. Sea nettles without stripes have a bell that appears white or opaque. It is most common along the coasts and feared by swimmers. Its painful stings are rated from moderate to severe but do not cause death. The sting is used to kill or stun both prey and predators. Nettles also keep people away from the water in the late summer.
The Stinging Nettle is symmetrical, marine, and carnivorous. Its mouth is located at the center of one end of the body. Its mouth opens to a gastrovascular cavity that is used for digestion. It has tentacles that surround the mouth to capture food. Nettles have no excretory or respiratory organs.
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Life cycle and reproduction
The nettle passes through two different body forms during its life cycle. The most familiar form is the medusa, while the smaller form is the larval stage. Jellyfish are either male or female. A few steps are required in order for a jellyfish to reproduce. First, the reproductive organs in the male (the gonads) develop in the lining of the gut. Second, the male releases sperm through its mouth column. Third, the sperm has to swim into the mouth of the female, which will fertilize the eggs that she has inside.
After that, early embryotic development begins either inside the female jellyfish or in brood pouches along the oral arms. Next, small, swimming larvae (planula) leave the mouth or brood pouches and enter the water column. Soon after, the larvae seek shade and attach to the bottom of the water, forming polyps. The polyps then divide and bud into young jellyfish (ephyra). In a few weeks, an ephyra will grow into an adult medusa, completing its complex life cycle. The jellyfish will live for three to six months if nothing happens to them.
Habitat
Sea nettles are most commonly seen near the coasts during the summer. Salinity and temperature are the two most important factors for a sea nettle habitat. They prefer water with little salinity, but can easily adapt. They eat their favorite meal, combjellies, in the Chesapeake Bay.
Feeding Habits
Stinging sea nettles are carnivorous. They feed on zooplankton, combjellies, and other jellies. They may also eat crustaceans. Nettles obtain food by stinging it with their tentacles. After that, the prey is transported to the gastrovascular cavity where it is then digested. Nettles also eat young minnows, bay anchovy eggs, worms, and mosquito larvae.
Defense Mechanisms
Sea nettles have tentacles that contain millions of microscopic stinging cells called nematocysts that inject toxins to stun or kill tiny animals and predators. Nettles use their tentacles as defense mechanisms against large predators and to capture their food. Some nematocysts contain toxic substances, while others are adhesive and help to entangle or anchor their prey.
Sting Treatment
Wash the stung area well with seawater. Do not rub the skin or wash with fresh water, as that will augment the pain. After washing, bathe the burnt area in moderately hot water for an hour (around 40 degrees Celsius). Contact a doctor if the pain does not subdue. Baking soda can often soothe the pain and help neutralize the formic acid component of the toxin.
Stings directly on the eyes may cause temporary loss of vision. Always contact a doctor in such cases. Severe burns on the eyes may in rare cases give scars or infected wounds and can in worst cases lead to impaired eyesight.