Also known as true jellyfish, scyphozoans can exist in both a polyp stage and a medusa stage. The medusa is the predominant stage. Scyphozoan medusae are larger then hydrozoan medusae, and are better swimmers. They can swim vertically and horizontally. Although many jellyfish are capable of swimming, not many of them are strong swimmers, and must float with the currents. Jellyfish have sense organs called photoreceptors that allow them to determine if it is light or dark out. Many species will avoid the sunlight, and come out when it is cloudy, or during twilight.
In adult jellyfish, the sexes are generally separate. The medusae are the sexual stage in the life cycle, and they release gametes into the water, where fertilization and early development take place. The fertilized eggs develop into larvae that spend time in the water before settling on a solid surface to form the polyp stage of the life cycle. The polyps reproduce medusa-like buds by asexual reproduction. The buds are released into the water to grow into medusae.
0 Comments
|
|