Discosomidae
Discosomidae is a family of scyphozoan jellyfish, commonly known as the “saucer jellyfish.” This family is characterized by its distinctive saucer-shaped bell, typically lacking tentacles, but possessing numerous short, trailing oral arms, which they use to capture prey.
Characteristics
Discosomid jellyfish are generally small in size, with bell diameters ranging from a few centimeters to a few decimeters. Their bodies are typically translucent and may display a variety of colors, including white, pink, orange, and brown. They are distinguished by their lack of tentacles, instead possessing a circular mouth surrounded by several short oral arms that are covered in stinging nematocysts.
Environment and Distribution
Discosomid jellyfish are found worldwide, inhabiting a variety of marine environments, including coastal waters, open ocean, and estuaries. They are often associated with coastal environments, particularly in warmer waters, and can be found in both shallow and deep water habitats.
Life Cycle
Discosomid jellyfish exhibit a typical scyphozoan life cycle, involving an alternation of generations. This life cycle includes the following stages:
- Planula Larva: The first stage, a free-swimming larva, develops from fertilized eggs.
- Polyp: The larva settles on a substrate and develops into a sessile polyp, which reproduces asexually by budding.
- Ephyra: The polyp releases small, free-swimming ephyrae, which are essentially miniature jellyfish.
- Medusa: The ephyra grows and develops into the adult, sexually reproducing medusa.
Diet
Discosomid jellyfish are carnivorous, feeding primarily on zooplankton, including copepods, small crustaceans, and other tiny invertebrates. They capture prey with their stinging nematocysts, which are located on their oral arms.