What animal group lacks true tissues and includes species that are asymmetrical?

The animal group that lacks true tissues and includes species that are asymmetrical is the group of sponges, also known as Phylum Porifera. Here are the steps to arrive at this answer:

1. Start by understanding the question: We need to find an animal group that has no true tissues and includes species that are asymmetrical.

2. Recall the basic animal groups: These are typically divided into vertebrates and invertebrates, and then further divided into various phyla.

3. Consider the characteristics of each group: Most animal groups have true tissues and are symmetrical. However, sponges (Phylum Porifera) are known for lacking true tissues and being asymmetrical.

4. Therefore, the answer is Phylum Porifera, or sponges.