Why do you think choanocyte chambers are so much larger than the other canals in most sponges? Think about how a sponge would benefit from large chambers in terms nutrient and gas exchange, and excreting wastes. Explain your answer.

Which of the following in sponges form the outermost epithelium-like layer that is in contact with the external, aquatic environment? a. Pinacocytes and choanocytes b. Pinacocytes only c. Choanocytes and collencytes d. Pinacocytes and collencytes e. Choanocytes only  f. Collencytes only

Relative to asconoid organization in sponges the syconoid form exhibits smaller body size increased spongocel volume relative to pumping surface area reduced spongocel volume relative to pumping surface area larger body size

Spider Compare the spider to the clam and earthworm. What are the functions of the structures inside the spider? How are the internal contents of the cephalothorax compare to those of the abdomen? What is the ecological and economic importance of spiders?