The cnidarian phylum has three divisions. Among them is the Scyphozoa class, represented mainly by jellyfish, popularly known as jellyfish. This class of cnidarians presents the main characteristics present in the phylum. Thus, it is possible to identify radial symmetry, external epidermis and gastrodermis.
The class Scyphozoa is very common throughout the world. Thus, it is found in tropical seas, oceans and even in the Arctic. The most favorable place to find jellyfish is coastal waters. However, these animals also live in the depths of the sea. Thus, some are classified as mobile and others as sessile, that is, there is no movement.
It is estimated that around 200 species are known today, the majority of which are jellyfish. Furthermore, they are invertebrate animals with varying morphology and size according to the species.
Characteristics of the class Scyphozoa
The class Scyphozoa is mainly composed of jellyfish, jellyfish and cassiopea. Commonly found in the seas, these animals have an invertebrate body with the presence of an external epidermis and internal gastrodermis. Furthermore, they have a type of gelatin called mesoglea that opens outwards.
Formats may vary depending on the species. Thus, there are scyphozoans that have a round shape and others that are cylindrical. Furthermore, these animals have tentacles responsible for transmitting a poisonous toxin. If in contact with human skin, it can cause burns and edema.
Regarding food, scyphozoans can be filter feeders or predators. In other words, for feeding to occur, they can filter seawater or, in some cases, the food tends to be other marine species.
Some species of jellyfish are used by humans in cooking. Furthermore, these animals are constantly used by science for studies on the treatment of some diseases. The part studied is the collagen present in some species.
How does reproduction happen?
Among the scyphozoan species, jellyfish are the only hermaphrodites, that is, they can change sex. In this way, at the time of fertilization – which can be direct or indirect – the egg is released in the form of a young scyphozoan, in the direct case. In indirect development, the stage in which the egg becomes a larva first occurs. The larva then develops into the adult stage.
Scyphozoic animals do not have nervous tissues, that is, cephalization is non-existent in these animals. In this sense, the brain is not part of the morphological composition of scyphozarians. However, some species have spots sensitive to light.