There are fewer phytoplanktons in the mesopelagic zone because of LOWER LIGHT LEVELS. It is the area of the ocean that is just below the epipelagic zone. This area of the ocean extends from a depth of 200 to 1000 meters.
Answer;
Phylum Nematoda.
The heartworms belongs to the phylum Nematoda.
Explanation;
-Phylum Nematoda are un-segmented organisms with anterior lateral chemosensory organs (amphids) and with a persistent blastocoel or pseudocoelom; dorsal and ventral nerve cords in epidermis and excretory system of renette cells or tubules.
-The alimentary canal is provided with distinct mouth and anus (complete digestive tract).
Cellular respiration allows carbon to enter water, that is a process that allows cells to get energy from nutrients.
C. Flood protection is the answer