Question

The animals in which coelom originates as a space in the mesoderm are termed as
A. Acoelomates
B. Pseudocoelomates
C. Schizocoetic and enterocoelic
D. All of the above

Answer 1

Animals have a certain hole or cavity-like structures in their body to either help them have buoyancy (if aquatic), excretion, digestion, breathing, etc. There are various kinds of coelems depending on the complexity of the microorganism.

Step by step answer: A body cavity in the body wall or intestinal canal is called coelom. It could help the microorganism to excrete their internal fluids, act as a skeleton, could be a protective cushion, etc. They form the storage space for eggs. They have a contribution in providing flexibility.
In humans, the largest body cavities are the ventral cavity and the dorsal cavity.
Option A: Acoelomates: The animals without a coelom cavity are acoelemates. They lack the fluid-filled cavity.
Option B: Pseudocoelomates: The simpler phyla like Porifera, protozoa, Platyhelminthes are acoelomate/pseudocoelomate as they do not have a mesodermal line of cells surrounding their coelom.
Option C: Schizocoelic and enterocoelic: A coelom between the digestive tract and musculature of the body wall made by the splitting of mesodermal cells is schizocoel. Example-Annelida and Mollusca. Enterocoelic is the coelom arises from the endoderm of the embryonic gut. They are formed from the primitive gut which has broken off and formed coelom. example- Echinodermata and Chordata
Hence, the answer is option C: Schizocoetic and enterocoelic

Note: The coelom enables the internal organs to move independently. The coelemates are mollusks, annelids, some arthropods, etc. It will help in the compartmentalization of body parts. It will protect from shock and compression. Worms and jellyfish lack coelom. In mollusks, the coelom is undifferentiated.