Answer to Question 1
D
Answer to Question 2
The moon and the sun both influence the movement of the tides but the moon generates the strongest tractive forces because of its close proximity to earth. Earth and moon are in a stable orbit with one another and as they orbit together, the moon's gravity attracts the surface of the ocean. Because Earth's mass is 81 times that of the moon, the center of mass between the two bodies is 1,000 miles inside Earth. Earth's motion around the center of mass of the Earth-moon rotation results in two tidal budges. The sun also affects tides but because it is so far from Earth, the sun's influence on the tides is only 46 that of the moon. If Earth, the moon, and the sun are all in a line, the lunar and solar tides will be additive, resulting in higher high tides and lower low tides, or a spring tide. But if the moon, Earth, and sun form a right angle the solar tide will tend to diminish the lunar tide, resulting in a neap tide, where high tides are not very high and low tides not very low.
Reconnect all vacuum and air hoses and tubes. Replace any vacuum hoses that are brittle or swollen ...
The normal food link between sea urchins and algae/ Corals
Tunicate larva (Ascidia), early metamorphosis. LM.
Smooth Brittle Star.
Free-swimming tunicate larva
Brittle Star