* = my answer
16. List the characteristics common to all animals. Name at least three. (3 points)
*All animals are made up of eukaryotic cells, they’re all heterotrophs, and they all have a soft cell membrane.
17. How do structures of the digestive tracts of a flatworm and an earthworm differ? (3 points)
*A flatworm has a combination digestive system. It takes food in and eliminates the rest through the same opening.
An earthworm eats dirt, digested the plant and animal matter (in the dirt) and then gets rid of the rest. It has a gullet for the food to go down, a gizzard to store the food to pass through and takeout nutrients, and an anus for the food to come out of.
18. How is a sponge’s food-gathering technique adapted to its sessile lifestyle? (3 points)
*A sponge doesn’t move so it has to be able to get food to come to it. Moving water carries nutrients and food resources in its currents. The sponge merely has to absorb the passing water and digest any nutrients it contains. The clean water is excreted and the process repeats. So long as the water continues to move around it, the sponge gets fed without having to travel.
19. A biologist places a single, living sponge in a saltwater tank. After several weeks, the biologist observes other small sponges living in the tank. Because the biologist is certain that no other sponge was introduced into the tank, what other explanation could you provide to explain the observation? (3 points)
*Asexual reproduction; they can reproduce asexually when a piece of the adults body breaks off and grows into a separate adult.
20. Describe the body of a leech. In what way do the leech’s adaptations make it suited for its niche? (3 points)
*Large mouth relative to body, large storage capacity, sticky, it has an anterior (head region) sucker which secretes an anesthetic so the host isn’t aware of its presence and it draws in blood.
21. When natural disasters strike natural areas, often the only animals to survive are the insects. Explain why this might happen. (3 points)
*Some insects thrive on natural disaster. Insects such as flies, colonize and breed on dead animals and plants. People that are homeless and living in the open can increase the exposure to mosquitoes and other insects that spread disease.
22. What three methods do echinoderms use to get food?
*1. Filter Feeding: Crinoids wave their tentacles through the water which trap plankton from sticky mucous. Mucous then flows down their tentacles into their mouth.
2. Active Predation: Starfish clams it attack muscles by prying open shells and then extending their stomach out of their mouths. After its stomach covers the prey then it’s digested.
3. Scavenging: Sea Cucumbers use their own tentacles to pass sediment to their mouth from the ocean floor.