While trying to find out the characteristic of a newly found animal, a researcher did the histology of adult animal and observed a cavity with presence of mesodermal tissue towards the body wall but no mesodermal tissue was observed towards the alimentary canal. What could be the possible coelome of that animal?

The correct answer is Pseudocoelomate

Concept:

• Animals can be classified based on the type of body cavity or coelom they possess. The coelom is a fluid-filled cavity between the body wall and the internal organs, providing space for organ development and function.
• There are three main types of coeloms found in animals: acoelomates, pseudocoelomates, and coelomates (schizocoelomates or enterocoelomates).
• In pseudocoelomates, the body cavity is present but it is not lined entirely by mesodermal tissue. Mesodermal tissue is observed only towards the body wall, and not towards the alimentary canal.

Explanation:

• Pseudocoelomate: Based on the researcher’s observation of the cavity lined with mesodermal tissue towards the body wall but not towards the alimentary canal, the animal has a pseudocoelom. In pseudocoelomates, the coelom is derived from the blastocoel rather than being completely surrounded by mesoderm. Examples include roundworms (nematodes).

Other Options:

• Acoelomate: Acoelomates lack a body cavity entirely. Their mesoderm fills the space between the body wall and the alimentary canal. Examples include flatworms (Platyhelminthes). 
• Schizocoelomate: Schizocoelomates have a true coelom that is formed by the splitting of mesodermal tissue during embryonic development. The coelom is completely lined by mesodermal tissue. Examples include annelids, mollusks, and arthropods.
• Spongocoelomate: Spongocoel refers to the central cavity found in sponges, which is not a true coelom.