The key difference between zooplankton and phytoplankton is that the zooplankton is heterotrophic non-photosynthesizing plankton that is either protozoan or an animal while the phytoplankton is autotrophic photosynthetic plankton that is either a diatom, cyanobacteria or algae.
Planktons are the tiny organisms that live and float in the oceans, seas or freshwater bodies. Most of them are microscopic, and they are important food sources for larger animals. There are two main types of planktons namely zooplankton and phytoplankton. Zooplanktons are heterotrophic, and they include animals that are not capable of photosynthesising. On the other hand, phytoplankton is photosynthetic plankton, which is autotrophic. Besides, phytoplanktons store energy via photosynthesis and zooplankton and nekton (large-bodied animals that actively move in the water column) feed on those. Humans and other predators feed on nekton and some larger zooplankton in large scale. Also, the human activities such as environmental pollution, largely affect negatively on this energy flow that starts from phytoplankton.
CONTENTS
1. Overview and Key Difference
2. What is Zooplankton
3. What is Phytoplankton
4. Similarities Between Zooplankton and Phytoplankton
5. Side by Side Comparison – Zooplankton vs Phytoplankton in Tabular Form
6. Summary
What is Zooplankton?
Zooplankton includes the small animals those swim or float in the water column. According to the developmental stages in their lifecycles, the zooplankton is of two groups namely, meroplankton and holoplankton. Meroplankton constitutes mainly larvae of cnidarians, crustaceans, molluscs, insects, echinoderms and some fish. They spend only a little time period of their lifecycle as plankton whereas; the holoplankton spends their whole life being plankton. Holoplankton includes pteropods, polychaetes, larvaceans, copepods and siphonophores.
Hence, zooplanktons include members from almost all the Phyla of the animal kingdom; Protozoa, Cnidarians / Coelenterates, Arthropods, Molluscs, Echinoderms, and Chordates. They are able to either swim or float using different techniques such as fat bodies, oil droplets, pneumatophores, ion-replacement techniques, etc.
Figure 01: Zooplanktons
Furthermore, one of the most interesting features of zooplankton is that they are capable of showing a unique phenomenon called the vertical migration, where they move towards to surface of the water in the nights and move down to deep water during daytime. Vertical migration helps them to be safe from the diurnal predators and allow the phytoplankton to produce food during daytime those could forage at night. During these movements, zooplanktons use water currents as well as active swimming.
What is Phytoplankton?
Phytoplankton is a small plant-like organism in the water column, mostly inhabiting the euphotic zone, aka sunlit volume, of the water body. Diatoms (more than 50,000 species), cyanobacteria, dinoflagellates (more than 2000 species), and algae (e.g. red and green algae) are some of the most common groups of phytoplankton.
Figure 02: Phytoplanktons
Moreover, these organisms are able to store the energy of the sunlight in the form of food. Thus, they are the autotrophic organisms of aquatic ecosystems. Especially they are responsible for the world’s maximum primary production, which is almost 200 billion kilocalories per year. Out of the Earths’ primary production, phytoplankton accounts for over 50% of production. Unlike zooplanktons, phytoplankton cannot swim against the water current, i.e. those are not active swimmers and therefore, zooplankton and nekton could easily prey on those.
What are the Similarities Between Zooplankton and Phytoplankton?
- Zooplanktons and phytoplanktons are two types of planktons.
- They are mostly microscopic organisms inhabit in oceans, seas and freshwater
- Also, both are indicators of ocean health.
- Furthermore, they both are very susceptible to changes in the marine environment.
- Besides, the phytoplanktons are the primary food source for the zooplankton.
What is the Difference Between Zooplankton and Phytoplankton?
Zooplanktons are animal-like planktons that drift in water currents but, phytoplanktons are plant-like planktons that drift in water currents. Also, zooplanktons are heterotrophic while phytoplanktons are autotrophic. Therefore, this is the key difference between zooplankton and phytoplankton. Furthermore, zooplanktons show vertical migration while phytoplanktons are not capable of showing the vertical migration. So, this is another difference between zooplankton and phytoplankton. A significant difference between zooplankton and phytoplankton is that the zooplankton inhabits in darker and cooler places of water while the phytoplankton inhabits on the surface of the water.
Furthermore, zooplankton can move while phytoplankton cannot. Phytoplankton just floats with water. So, this is also a prominent difference between zooplankton and phytoplankton. Protozoans and tiny animals are zooplanktons while diatoms, algae, dinoflagellates and cyanobacteria are phytoplankton.
The below infographic presents more details on the difference between zooplankton and phytoplankton.
Summary – Zooplankton vs Phytoplankton
Planktons are drifting organisms that inhabit the water column of oceans, seas, and bodies of fresh water. Some are plant-like while some are animal-like. Plant-like planktons are phytoplanktons while animal-like planktons are zooplanktons. So, in summarizing the difference between zooplankton and phytoplankton, we can say that the zooplanktons are heterotrophic while phytoplanktons are autotrophic. Moreover, zooplanktons are unable to photosynthesize and release oxygen while phytoplanktons can photosynthesize and release oxygen. Furthermore, zooplankton shows vertical migration while phytoplankton cannot. However, phytoplankton produces maximum primary production and they are important food sources for other organisms.