U is for Upsidedown Jellyfish
The upsidedown jellyfish is inverted compared to other jellyfish. It is usually yellowish-brown with white spots. The flattened disc part is at the bottom with the arm cluster oriented upward. The whole animal has a translucent appearance. They grow to a size of 4-5 inches, rarely exceeding 10V2 inches.
Upsidedown jellyfish live in shallow sea areas such as flats, lagoons and back reef areas. They are found on the bottom, sitting in the sand with their arm cluster upward. Their flat part acts as a suction cup on the bottom, holding the jellyfish in place. These animals initially are free swimming, but once they reach about 1 inch in size, they settle on the sea floor.
These jellyfish do not have one centered mouth; they have over 40 openings along mouth arms that create little canals. Jellyfish are carnivorous, dining mostly on a variety of zooplankton. They gather the small prey with their arms as it floats by them, stinging their prey with a toxic substance. Part of their food also comes from algae that grow in their arm clusters nourished via photosynthesis. This algae not only provides food, it also provides oxygen to the jellyfish.
Jellyfish are either male or female; they reproduce sexually. Reproductive organs are in the lining of the gut. Males release sperm through their mouth, which swim into the mouth of the female and fertilize her eggs. Development of the eggs occurs inside the female or in brood pouches located on the jellyfish's arms. Larvae emerge that form polyps, which divide and become young jellyfish.
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