Food Webs in the Ocean

Overview

• Food webs illustrate energy flow in an ecosystem by showing what eats what.
• Consist of multiple food chains.
• Most oceanic food chains have at least four levels.

Level 1: Producers

• Producers use energy from the sun via photosynthesis.
  • Coastal Producers: Seaweed and sea grasses.
  • Ocean Producers: Phytoplankton (tiny, one-celled plants), mostly invisible to human eye.
• Live near ocean’s surface because they rely on sunlight.
• Phytoplankton make up about 1% of all living things and produce around 50% of the world's oxygen.

Level 2: Herbivores and Omnivores

• Consumers need to eat to get energy, unlike producers who get energy directly from the sun.
• Large Herbivores: Turtles, sea cows, and sea urchins (diet of seaweed and seagrasses).
• Zooplankton: Drifting animals like barnacles, mollusks, krill, and jellyfish.
  • Consume phytoplankton, bacteria, and detritus.

Level 3: Carnivores

• Eat other animals exclusively.
• Smaller Carnivores: Sardines, squid, octopuses, and various fish species.
  • Predators of zooplankton.
  • Serve as prey for larger carnivores.

Level 4: Top Predators

• Top Predators are superior hunters and are rarely preyed upon, except by humans.
• Characteristics: Big, fast, better hunting skills, long lifespans, slow reproduction.
• Examples include whales, dolphins, sharks, tuna, penguins, pelicans, seals, walruses, polar bears, and sea lions.