Kehaõõtude

Kehaõõtude, often translated as body cavities, are fluid-filled spaces within the bodies of multicellular animals that house internal organs. These cavities play a crucial role in protecting organs from mechanical shock, allowing for organ expansion and contraction, and facilitating the movement of organs within the body. The presence and arrangement of body cavities are important characteristics used in biological classification.

In vertebrates, the primary body cavities are the dorsal body cavity and the ventral body cavity. The dorsal cavity is further divided into the cranial cavity, which houses the brain, and the vertebral cavity, which encloses the spinal cord. The ventral cavity is the larger of the two and contains the thoracic cavity and the abdominopelvic cavity. The thoracic cavity, separated from the abdominopelvic cavity by the diaphragm, houses the heart and lungs. The abdominopelvic cavity contains organs of the digestive, urinary, and reproductive systems.

Invertebrates exhibit a wider variety of body cavity arrangements. Some, like sponges and cnidarians, lack true body cavities altogether. Others, such as nematodes, possess a pseudocoelom, a false body cavity not fully lined by mesoderm. Arthropods and annelids possess a coelom, a true body cavity that develops from the mesoderm. The coelom allows for greater complexity in organ arrangement and function. The specific arrangement and type of body cavity are key features in understanding the evolutionary relationships and anatomical diversity of the animal kingdom.