SEE FORUMS (Chapter 7, Page 152)

Critical Thinking - Question 3

A new class of echinoderms, the sea daisies or concentricycloids, was discovered in 1986. They are deep-water animals living on sunken wood. They are flat and round, looking very much like a small sea star without arms. They also lack a gut. Without ever having seen them, why do you think they were classified as echinoderms, not as members of a new phylum? Any hypotheses as to how they feed or move around?

I think the sea daisies were classified as echinoderms and not as members of a new phylum simply because they look very much like a small sea star without arms. Having this similarity definitely would mean that they are related somehow.

Hypotheses: Sea daisies feed and move around using the central part of their body.


STUDENT NOTES ONLY:
Echinoderms - Invertebrates (no back bone) with five-way radial symmetry (the regular arrangement of similar body parts around a central axis) and a water vascular system (a network of water-filled canals in echinoderms used on locomotion and food-gathering). Examples are sea cucumbers, starfishes, sea urchins, etc.

Phylum - The taxon (a group of organisms that share a common ancestry) that represents a main division of a kingdom

Hypotheses - A statement that might be true.


CITE: Picture obtained from http://images.google.com/images?gbv=2&svnum=10&hl=en&q