MARINE LIFE Different creatures live at different ocean

MARINE LIFE

Different creatures live at different ocean depths. Below are just a few. Kelp and mollusks are benthic organisms. They tend to live at the bottom of the ocean Fish and whales are free-swimming (i. e. nekton) organisms which live in various depths. Small drifting bacteria, protists, plants and animals (e. g. plankton) are the dominant life and food source in the ocean. CLASSIFICATION

Phytoplankton are the food source for many marine creatures. The majority of marine life is dependent on the presence and health of phytoplankton. This is because phytoplankton carry out photosynthesis near the ocean’s surface. Phytoplankton form the basis of the marine food chain just like plant life forms the basis of our food chain. Phytoplankton only “consume” light. Zooplankton eat phytoplankton and other microscopic organisms. They can be found in fresh or salt water. They are right above phytoplankton in the marine food chain. PHYTOPLANKTON & ZOOPLANKTON

Most marine life is heavily concentrated in surface waters (like those off the coast of Chile) because that’s where there’s the most light. Creatures that live in the deep waters depend on the abundance of creatures in higher life zones. If the number of creatures in the upper zones decreased, the number of deep water creatures would shrink drastically. NUTRIENTS

A life zone is determined by the plants and animals that can live there. Life zone regions are categorized by how deeply light penetrates that region. The availability of light determines the amount of nutrients available and whether photosynthesis is possible. The bottom most zone (the benthic zone) extends from the sunlit continental shelf to the dark ocean depths. Not many creatures live at the bottom of the ocean because of the lack of light. The pelagic zone deals with the open ocean; the open ocean lies over the continental shelf. The water in this zone is shallow and filled with lots of light. It contains 90% of the sea’s creatures. LIFE ZONES

Marine Life Zone Diagram

1. Why is most marine life dependent on phytoplankton? 2. Imagine that the ocean was kept in complete darkness. What would happen to the phytoplankton? 3. How would the disappearance of phytoplankton affect marine life? QUESTIONS