Question

В чем примитивное строение животных имеющих первичную полость ?

Answer 1

Первичная полость тела содержит полостную жидкость и форма тела поддерживается только благодаря этой полостной жидкости. А стенки вторичной полости тела прекрасно поддерживаются мускулами. И вторичная полость тела может образовывать внутренние органы, а первичная - нет.

Answer 2

Primitively Structured Animals with a Primary Body Cavity

The primitively structured animals having a primary body cavity are known as Coelenterates. Coelenterates are a group of simple aquatic animals including the hydra, jellyfish, sea anemones, and corals. They have a sac-like body with a central digestive cavity and tentacles around the mouth. This cavity serves as both a digestive and circulatory system, allowing for the intake of food and expulsion of waste.

Coelenterates have a relatively simple body plan, with radial symmetry and a single body opening that serves as both the mouth and anus. They lack specialized organs for circulation, respiration, and excretion, relying instead on diffusion for these processes.

The primary body cavity in coelenterates is known as the coelenteron, which functions as a digestive cavity. This cavity is lined with cells that aid in digestion and nutrient absorption. The coelenteron also serves as a hydrostatic skeleton, providing support for the animal's body and allowing for movement.

Coelenterates are considered primitively structured due to their relatively simple body plan and lack of specialized organ systems found in more complex animals. They represent an early stage in the evolution of multicellular organisms and exhibit characteristics that are fundamental to understanding the development of more advanced animal phyla