I do not undertsand this biology question...?

[M&C]

Animals are placed in taxonomic classifications based on differences and similarities of their traits. If you know what critical traits to look for, it is possible to separate any animal
into a taxonomic category.
The common categories are Domain, Kingdom, Phylum, Class, Order, Family, Genus and Species (Specific Epithet.
The images are examples of nine Animal Phylum: Porifera, Cnidaria, Nematoda, Arthropoda, Platyhelminthes, Annelida, Mollusca, Echinodermata, and Chordata.

1. Which group(s) lack tissue level organization?

2. Which group(s) of organism(s) begins to show cephalization?

3. Do all organisms on the chart have 3 germ layers (endoderm, ectoderm and mesoderf not which groups lack all three?

4. One group has more species than all the other groups, give the name of the Phylum and examples of species found in this group.
5. Do all fish have the same skeletal structures? If not, describe the differences.
6. Describe the 3 different types of mammel