What are the differences between the early development of a mammal vs. that of the worm, etc?

In terms of development of the embryo, what are some body plans that can arise? What are the differences between the early development of a mammal vs. that of the worm, etc?

2. Animals are classified by body plan and levels of overall complexity. Explain, using an example, of how embryogenesis and adult characteristics relate to the phylogeny of the species.
Please do not forget to include your references and in-text citations
3. The insect Drosophila melanogaster and the nematode Caenorhabditis elegans are important model organisms for scientific and medical research. Are these species the most appropriate invertebrates for making inferences about humans and other vertebrates? Why or why not?

4. Sponges are interesting in that they lack ‘true tissues’. They have several cell types but lack ’tissue’ status. Why is this? What classifies as being a tissue? How many tissues do we have as humans?