The organisms in the ocean are diverse and numerous, as they are on land. In fact, most scientists would concur that the ocean has a “universe” of its own, ruled by principles and laws only applicable on water. There are several interesting classifications of organisms based on different criteria.
*The general classification of marine organisms is based on 5 significant kingdoms. Each kingdom is characterized by specific traits that identify them from the rest.
1. Protista – these are protozoans, which are single-celled organisms that can move by the use of pseudopods, cilia or flagella. They can either be autotrophic (produce carbon-related compounds like carbohydrates, proteins and fats,) or heterotrophic (non-carbon related) organisms. Examples of these are algae and amoebae. The zooplanktons like mollusks and annelids are also considered as protozoans.
2. Monera – these are bacteria, which are also single-celled organisms. There are pathogenic and symbiotic bacteria which aid in the maintenance of the balance between existing living organisms. They can also help in the catabolism of environmental substances to maintain marine life balance. An example is the Phytoplankton group.
3. Fungi – these are eukaryotic organisms, which take active role in decomposing organic material to provide food for other organisms. Sometimes they infest other marine organisms to cause illness.
4. Metaphyta – these include marine plants. These are autotrophic living things like eel grass and turtle grass. They grow by photosynthesis, just like their land counterparts. Chromists, like seaweeds, are classified from other plants because they utilize photosynthesis differently.
5. Metazoa – these include animals, which are multi-celled organisms like jellyfish, fish, whales, mussels and the like. They survive by feeding on other marine organisms.
*Another classification is based on their lifestyle
1. Plankton – are marine organisms that do not have the ability to swim against the water current. They are divided into phytoplankton (plants) and zooplankton (animals). Phytoplankton include cyanobacteria like the blue-green algae, dinoflagellates, silicoflagellates, chrysophytes, prasinophytes and similar organisms.
2. Benthos – are organisms that live on the bottom of the water or on the seabed, or within the bottom of water sediments. Examples of these marine organisms are sea anemones, lobsters, sea cucumbers and corals.
3. Nekton – are marine organisms that could swim, like, squid, fish, birds, mammals and reptiles.
*Classification according to nutrition
1. Autotrophs – are those that make use of carbon dioxide to produce organic compounds. They are capable of photosynthesis and chemosynthesis. All marine plants are autotrophs. Some marine bacteria belong to this category as well.
2. Heterotrophs – are those that consume organic compounds. These include non-autotrophs.
3. Mixotrophs – these are marine living things that may either be an autotroph or a heterotroph.
These are the major classifications of ocean organisms which are worth knowing. After all, they are part of the planet earth, which you call home.