Which of these animals 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, responsible for forming structures such as muscles, bones, and the circulatory system. Pigeons, dogs, and turtles are vertebrates and possess a mesoderm during their embryonic development. Jellyfish, however, are invertebrates belonging to the phylum Cnidaria, and they do not have a mesoderm. The jellyfish lacks this germ layer, relying instead on two primary layers: the ectoderm and endoderm.
The animal that does not have mesoderm is the jellyfish. This is due to its simpler body plan and developmental processes compared to vertebrates.
Which of these animals does not have mesoderm: pigeon, dog, turtle, jellyfish? - in detail
To determine which of the listed animals does not have mesoderm, it is essential to understand the basic principles of animal embryology and the development of germ layers. Mesoderm is one of the three primary germ layers that form during the early stages of embryonic development in most animals. The other two germ layers are the ectoderm and endoderm. The mesoderm gives rise to various tissues and organs, including muscles, bones, blood, and the circulatory system.
Pigeons, dogs, and turtles are all vertebrates, and they exhibit the typical triploblastic condition, meaning they have three germ layers: ectoderm, mesoderm, and endoderm. These animals undergo a well-defined process of gastrulation, where the mesoderm forms and differentiates into various specialized tissues. For instance, in pigeons, the mesoderm contributes to the development of the heart, blood vessels, and skeletal muscles. In dogs, the mesoderm is crucial for the formation of the muscular and skeletal systems, as well as the circulatory and urogenital systems. Similarly, in turtles, the mesoderm is involved in the development of the heart, blood vessels, and the muscular and skeletal systems.
Jellyfish, on the other hand, belong to the phylum Cnidaria, which are diploblastic animals. This means that jellyfish have only two germ layers: ectoderm and endoderm. The mesoderm is absent in jellyfish, and their body plan is simpler compared to triploblastic animals. The ectoderm in jellyfish forms the outer layer of the body, including the epidermis and nerve cells, while the endoderm lines the gastrovascular cavity and contributes to the formation of digestive cells. The absence of mesoderm in jellyfish results in a lack of complex organs and tissues that are typically derived from the mesoderm in higher animals.
In summary, among the listed animals, the jellyfish is the one that does not have mesoderm. This fundamental difference in germ layer composition reflects the evolutionary divergence between diploblastic and triploblastic animals, with jellyfish representing an earlier evolutionary stage characterized by a simpler body plan.