Both assertion and Reson are correct.. because kingdom animalia divided into unicellular and multicellular organisms ..multicellular organisms further classified into metazoa (cnidarians to mammals), parazoa (includes only poriferans).....

Phylum Porifera: An Evolutionary Blind Off Shoot?

Introduction:
Phylum Porifera, commonly known as sponges, is a group of simple aquatic animals that lack true tissues, organs, and symmetry. They are considered the most primitive and ancient group of animals in the Kingdom Animalia. Some scientists have argued that Porifera is an evolutionary blind offshoot, while others believe that they are a successful and diverse group of animals that have persisted for over 600 million years.

Phylum Porifera: An Evolutionary Blind Off Shoot?
The assertion that Phylum Porifera is an evolutionary blind offshoot implies that they have remained unchanged for millions of years and have not evolved into any other group of animals. This statement is not entirely accurate because sponges have undergone a few important evolutionary changes over time.

- Genetic Evidence:
Recent genetic studies have shown that sponges are a sister group to all other animals. This discovery indicates that sponges are not a blind offshoot but a critical part of animal evolution.
- Evolutionary Changes:
Although sponges have not evolved into any other group of animals, they have undergone significant evolutionary changes. For example, they have developed a variety of body forms, including encrusting, vase-shaped, and branching. They have also evolved specialized cells such as choanocytes, which are similar to the cells found in the collar of the flagellates.
- Ecological Significance:
Sponges play an important ecological role in marine ecosystems. They are filter feeders that can filter up to 1500 liters of water per day, making them an essential component of nutrient cycling in the ocean. They also provide habitat and shelter for many other marine organisms.

Conclusion:
In conclusion, Phylum Porifera is not an evolutionary blind offshoot but a critical part of animal evolution. While they have not evolved into any other group of animals, they have undergone significant evolutionary changes and play an essential ecological role in marine ecosystems. Therefore, it is incorrect to consider Phylum Porifera as an evolutionary blind offshoot.