What does scyphozoa mean in Greek?
The class name Scyphozoa comes from the Greek word skyphos, denoting a kind of drinking cup and alluding to the cup shape of the organism. Scyphozoans range in geological time from the Ediacaran period through the recent.
How do you identify a scyphozoa?
Scyphozoans share a number of attributes with other cnidarians: (1) they typically possess tentacles, (2) their symmetry is radial, (3) the body wall consists of an outer epidermis and inner gastrodermis, separated by a layer of jelly-like mesoglea, (4) the mouth is the only opening to the digestive system, (5) …
Are scyphozoa medusae or polyps?
Hydrozoa: More on Morphology Most hydrozoans show the same alternation between polyp and medusa phases that the Scyphozoa, or “true” jellyfish, have. A fertilized egg develops into a sessile polyp, which buds asexually and eventually buds off one or more medusae.
Are scyphozoa harmful to humans?
Although the Scyphozoa are generally considered less dangerous, they are responsible for the majority of jellyfish envenomations throughout the world and life-threatening complications following this occurrence are possible [26].
How does a polyp turn into a Medusa?
Enter your search terms: In such organisms the polyp, by budding, gives rise to medusae, which either detach themselves and swim away or remain permanently attached to the polyp. The medusae then produce new polyps by sexual reproduction.
What is the role of polyp and medusa?
Polyp are a primitive form of cnidarians being sessile, reproducing mostly asexually, and lacking sense organs. In contrast, medusa are a more evolved form of cnidarians, being mobile, reproducing sexually which promotes genetic diversity, and presenting photoreceptors and statocytes as sense organs.
Does Medusa reproduce asexually?
One generation (the medusa) reproduces sexually and the next generation (the polyp) reproduces asexually. For both species, fertilized eggs develop into a multi-cellular planula and then into polyps that live on the sea floor.
What is Nematocyst and its importance?
Nematocysts are organelles that have stinging cells. They are present in Cnidarians. Nematocyst paralyses the preys by injecting poison and helps Cnidarians to catch their prey.
What is Nematocyst and importance?
Each is produced by a special cell called a cnidoblast and contains a coiled, hollow, usually barbed thread, which quickly turns outward (i.e., is everted) from the capsule upon proper stimulation. The purpose of the thread, which often contains poison, is to ward off enemies or to capture prey. Nematocyst. Quick Facts.