Types of Marine Organisms

• Plankton

Plankton is a collection of passively drifting small plants (phytoplankton) and animals (zooplankton) in the aquatic system. Although plankton can change their depth by actively swimming and changing their buoyancy, they can only move with the current and the movement of the water. The size of plankton varies greatly. Whether it is viruses and bacteria with a diameter of a few microns or jellyfish weighing 10 kg, they are all planktonic. Plankton is the productive base of marine and freshwater ecosystems, providing food for many large and small marine organisms. In addition, plankton also play a vital role in absorbing carbon dioxide and producing oxygen in the ocean.

• Marine plants

Marine plants are autotrophic organisms in the ocean that use chlorophyll for photosynthesis to produce organic matter. Marine plants can be simply divided into two main groups, namely the lower algae and the higher seed plants. Marine plants not only provide food and shelter for marine organisms, but also provide about 70-80 % of the oxygen on earth. Like terrestrial plants, marine plants depend on sunlight, so they only exist at depths that light can penetrate.

• Marine invertebrates

Marine invertebrates are invertebrates that live in marine habitats and comprise more than 90% of all marine animal species. Marine invertebrates include sea slugs, sea stars, sea urchins, coral polyps, ascidians, jellyfish, sea anemones, sea cucumbers, crabs, copepods, shrimp, sponges，and squid. They make up most of the macroscopic life in the ocean.

• Fish

Most fish are aquatic vertebrates with scales and gills, which means they have a skeleton which includes a cranium or skull and a functional backbone. Fish are often referred to as cold-blooded creatures, which means that their body temperature varies with the ambient temperature, although some large active swimmers such as white sharks and tuna can maintain a higher core temperature. At present, fish has become an important resource for human use around the world.

• Reptiles

Marine reptiles are reptiles whose primary habitat is located in a body of water. They have the potential to survive or adapt to climate change. They were particularly successful in the Mesozoic and became the main predators in the ocean. Most marine reptiles became extinct at the end of the Cretaceous, but some still existed during the Cenozoic, most importantly in species such as crocodiles, sea turtles, sea snakes, and marine lizards.

• Seabirds

Seabirds are birds that are adapted to living in a marine environment. They generally have a longer life span, breed later and produce fewer young compared to other birds. Seabirds depend on a healthy ocean for their survival and the health of the ocean can quickly and dramatically affect seabird populations. For this reason, scientists often use seabird population data as a barometer of ocean health.

• Marine mammals

Marine mammals are aquatic mammals that depend on the ocean and other marine ecosystems for their survival. They play an important role in the food web of marine ecosystems. In general, marine mammals are divided into four distinct groups, namely cetaceans, pinnipeds, sirenians and marine fissipeds.