sand dollar embryo

I am having trouble answering a question a student e-mailed me. Perhaps another student or TA can help me with this question, which can be found on the study guide for Ella Tour's lecture.

Discuss the similarities and the differences between the early development of a sand dollar embryo and a human embryo.

I don't recall hearing about sand dollars in Ella Tour's lecture, although I believe there were some remarks about sea urchins. Also, ch. 47 of the textbook makes consistent comparisons between sea urchin embryo development and mammalian embryo development. Sand dollars and sea urchins are very close relatives and are both in the Echinoid class of marine animals, and it would seem like they have very similar developmental patterns, however, I am not sure.

Can anyone else clarify?

I missed this lecture, I was out with the flu, but I'd say what you've got in thought sounds reasonable. Its always possible it was a typo and she meant to say sea urchin.

I asked a TA about this question from review session
he said that we only need to know that during the early stage of development,
we wouldn't really know or see the difference between the two
because it has just determined what kind of differences it will make. (fate is determined)
but later on as differentiation takes place in the development process,
the embryos will show specificity in their cells and will show differences.