Moon Jellyfish Behaviors & Adaptations

Aurelia aurita, or moon jellyfish, is the most common of the jellyfish species. It is a translucent jellyfish with horseshoe-shaped gonads at the top of its bell. The moon jellyfish is found throughout most of the oceans but thrives in tropical climates.

  1. Feeding

    • The moon jellyfish is a carnivore, with its diet consisting mostly of plankton. They also are known to eat a variety of crustaceans and larvae, mollusks, diatoms, eggs and protozoans. Moon jellyfish have a peculiar digestive adaptation. The foods collect on the surface of the jellyfish and become caught up in the animal's mucus, where they are then passed along to the lappets. The food is then moved by a flagellar motion along eight different canals that branch off and carry the food straight to the stomach. These feeding canals are unique to the moon jellyfish.

    Biology

    • Moon jellyfish are unique in that they do not possess respiratory parts. They do not breathe with lungs, gills or trachea. It diffuses oxygen from the water through a membrane. Low-oxygen water is expelled in the gastrovascular cavity and high-oxygen water comes in through ciliates. The animal has no circulatory or excretory systems. It is transparent with an umbrella membrane with tentacles attached to the bottom. Moon jellyfish vary in size from between 2 and 16 inches. They reproduce sexually and the females develop eggs in the gonads located at the bottom of the stomach.

    Behavior

    • The moon jellyfish has limited movement and generally moves along with ocean currents. When it does swim it does so by pulsations of the coronal muscle in its umbrella membrane. They move horizontally and stay near the surface of the water. It catches food with its tentacles as its prey swims by underneath it.

    Habitat

    • The moon jellyfish is most common in warm or tropical waters. They can withstand temperatures as low as 21 degrees and as high as 88 degrees. They live in both inshore seas and all major oceans, and they are a plentiful species. They tend to be found in brackish waters with low salt content. Their optimum temperature is water between 48 and 66 degrees.