Which animal does not have mesoderm: pigeon, dog, turtle, jellyfish? - briefly
The mesoderm is one of the three primary germ layers in the development of most animals, giving rise to tissues such as muscle, bone, and blood. Among the listed animals, the jellyfish is the one that does not have a mesoderm. This is because jellyfish belong to the phylum Cnidaria, which are diploblastic organisms, meaning they possess only two germ layers: the ectoderm and endoderm.
Jellyfish lack a true mesoderm, which is a characteristic that sets them apart from the other animals mentioned. The pigeon, dog, and turtle are all triploblastic animals, possessing the three germ layers: ectoderm, mesoderm, and endoderm.
Which animal does not have mesoderm: pigeon, dog, turtle, jellyfish? - in detail
The mesoderm is one of the three primary germ layers that develop in the early embryo of most animals. It gives rise to various tissues and organs, including muscles, bones, and the circulatory system. Understanding the presence or absence of the mesoderm in different animals provides insights into their evolutionary relationships and developmental biology.
Pigeons, dogs, and turtles are all vertebrates, which means they possess a well-defined mesoderm during their embryonic development. In pigeons, the mesoderm contributes to the formation of the skeletal system, muscles, and the heart. Similarly, in dogs, the mesoderm is crucial for the development of the muscular system, skeleton, and internal organs. Turtles also rely on the mesoderm for the formation of their shell, muscles, and other internal structures.
Jellyfish, on the other hand, belong to the phylum Cnidaria, which are diploblastic animals. This means they have only two primary germ layers: the ectoderm and the endoderm. The mesoderm is absent in jellyfish, and their body structure is simpler compared to vertebrates. The lack of a mesoderm in jellyfish results in a body plan that is primarily composed of a gelatinous mesoglea, which is not a true mesoderm but rather a non-cellular layer between the ectoderm and endoderm. This structural simplicity is a defining characteristic of cnidarians and distinguishes them from more complex bilaterian animals.
In summary, among the listed animals—pigeon, dog, turtle, and jellyfish—the jellyfish is the one that does not have a mesoderm. This distinction is fundamental to understanding the evolutionary and developmental differences between cnidarians and vertebrates.