Sea Nettle Jellyfish | Australian Spotted Jellyfish | Moon Jellyfish
The Sea Nettle Jellyfish (Chrysaora quinquecirrha) occurs particularly in Atlantic estuaries. The Sea Nettle Jellyfish is bell-shaped and usually semi-transparent with small, white dots and reddish-brown stripes. Sea Nettle Jellyfish without stripes have a bell that appears white or opaque.
The sting of this jellyfish is rated from moderate to severe and can be deadly to smaller prey. The sea nettle jellyfish is not, however, potent enough to cause human death, except by allergic reaction. While the sting is not particularly harmful, it can cause moderate discomfort to any individual stung. The sting can be effectively neutralized by misting vinegar over the affected area or applying ice. This keeps unfired nematocysts (venomous cells) from firing and adding to the discomfort.
The sea nettle jellyfish is carnivorous. They generally feed on zooplankton, ctenophores (Comb Jellies), other jellies and sometimes crustaceans. Sea Nettle Jellyfish also eat young minnows, bay anchovy eggs, worms and mosquito larvae. Their prey is immobilize using their stinging tentacles. After that, the prey is transported to the gastrovascular cavity where it is subsequently digested. The mouth of the sea nettle jellyfish is located at the centre of one end of the body, which opens to a gastrovascular cavity (both digestion and gas exchange) that is used for digestion. It has tentacles that surround the mouth to capture food. Sea Nettle Jellyfish have no excretory or respiratory organs. Each sea nettle is free-swimming and can reproduce both sexually (with fertilization) and asexually (without fertilization).
The Australian Spotted Jellyfish (Phyllorhiza punctata) is also known as the White-spotted jellyfish. The Australian Spotted Jellyfish is native to the southwestern Pacific, where it feeds primarily on various snail species.
This jellyfish averages 45 – 50 centimetres in bell diametre but a maximum size of 62 centimetres has been reported. However, in October 2007, an Australian Spotted Jellyfish with a diametre of 72 centimetres wide was recorded in the USA.
The Australian Spotted Jellyfish have only a mild venom and are not considered a danger to humans. However, their ability to consume plankton and the eggs and larvae of important fish species is cause for concern. Each jellyfish can filter as much as 13,200 gallons of sea water per day. While doing so, it ingests the plankton that native species require.
The Australian Spotted Jellyfish has been found in large numbers in Gulf of Mexico. While it is not known how it was introduced to the region, it has been theorized that budding polyps may have attached themselves to ships. As an invasive species, the Australian Spotted Jellyfish has become a threat to several species of shrimp. In Gulf waters, the medusae grow to unusually large sizes, a minimum of 60 centimetres across.
The Moon Jellyfish (Aurelia aurita) is also known as the ‘jelly’, ‘crystal jellyfish’, ‘common jellyfish’, ‘saucer jelly’ or ‘swimming jellyfish’. It is the most common jellyfish species found in the genus Aurelia. There are at least 13 species in the genus Aurelia including those that have still not been described.
Moon Jellyfish can be found in the Atlantic Ocean, the Arctic Ocean and the Pacific Ocean and are common to the waters off Europe, California and Japan. The Moon Jellyfish is translucent and can measure 25 – 40 centimetres across. Moon Jellyfish have characteristic patterns of colour within their bodies. They feed by stinging small medusans, plankton and molluscs with their tentacles and ingesting them into their bodies for digestion. Like other jellyfish, Moon Jellyfish drift with the current.
The Moon Jellyfish feeds on plankton which includes organisms such as molluscs, crustaceans, tunicate larvae, rotifers (microscopic fluid filled animals), young polychaetes (a class of annelid worms), protozoans (one eyed plants or fungi), diatoms (one eyed algae), eggs, fish eggs and other small organisms. Occasionally, Moon Jellyfish are also seen feeding on gelatinous zooplankton (a term used to describe the fragile animals that live in the water column in the ocean) such as hydromedusae (an order of the Hydrozoa) and ctenophores (commonly known as Comb Jellies).
Larvae of the Moon Jellyfish have nematocysts (venomous cells) to capture prey and also to protect themselves from predators. The food is tied with mucus and then it is passed down by ciliated action down into the gastrovascular cavity where digestive enzymes from the serous cell break down the food. (Cilia are tail-like projections extending approximately 5 – 10 micrometres outwards from the cell body)
The Moon Jellyfish does not have respiratory parts such as gills, lungs, or trachea (like spiracles). Since it is a small organism, it respires by diffusing oxygen from water through a thin membrane.
Moon jellyfish have been food for a wide variety of predators including the Ocean Sunfish (Mola mola), the Leatherback Sea Turtle (Dermochelys coriacea), a hydromedusa (Aequorea victoria) and the fried egg jellyfish or egg-yolk jellyfish (scyphomedusa Phacellophora camtschatica). They are also hunted by birds.