Nekton - Environment Notes
Nektons are aquatic organisms that live in water and can move around by swimming or by other methods. Nekton comes in a variety of sizes and forms. They can be found in both shallow and deep seas. Invertebrates like shrimp and vertebrates like fish are examples of nekton. This article will explain to you about Nekton which will be helpful in preparing the Environment syllabus for the UPSC Civil service exam.
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Table of Contents |
Nektons
What exactly are Nektons?
- Nekton (swimmers) are living organisms that can swim and move without being affected by currents.
- German biologist Ernst Haeckel first used the term nekton to distinguish between active swimmers in a body of water and plankton, which are passive organisms carried along by the current.
- Nektons can be found in either the photic or aphotic zones.
- In all marine food webs, they serve as a vital link between primary consumers and the higher trophic levels.
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| Neuston | Aquatic Organisms |
| Periphyton | Benthos |
| Plankton | Factors Limiting the Productivity of Aquatic Habitats |
Nekton- Features
- Nekton is a varied group of organisms with sizes ranging from a few millimeters to over 30 meters.
- The majority of nektons are vertebrates, with the exception of a few free-swimming mollusks and crabs.
- Vertebrates have backbones and are supported by endoskeletons, which are rigid internal skeletons formed of bone or cartilage.
- Nektonic animals feature unique characteristics that aid in swimming, navigating, and floating.
- Nektonic organisms can sometimes be carnivores, which eat other consumers, or herbivores, which eat plants and algae, and omnivores, which eat both.
- Because nekton is always looking for food, they must be able to swim long distances.
Oceanic Nekton
Animals from three taxonomic groups make up the majority of the oceanic nekton:
- Vertebrates: Vertebrates make up the majority of the community. These animals are supported by bones or cartilages.
- Mollusks: Mollusks are organisms that have a soft body with no distinct sections and have a hard outer shell. Squids and scallops are examples of mollusks.
- Crustaceans: There are species whose beginning life stage is characterized as planktonic, but they become nektonic as they grow and increase in body size.
- Lobsters and crabs are examples of crustaceans.
Conclusion
Although a few nearshore nektons and shallow-water nektons graze on plants, herbivorous nektons are not very common. The barriers of temperature, salinity, nutrient supply, and kind of sea bottom usually limit the areal and vertical distributions of nektonic organisms. With increasing depth in the ocean, the number of nektonic species and individuals diminishes.
FAQs
Question. What is nekton?
Answer: Nekton refers to the group of aquatic organisms that are capable of swimming actively against currents, typically including fish, marine mammals, and certain types of mollusks.
Question. How do nekton differ from plankton?
Answer: Nekton are organisms that can swim and navigate through water, while plankton are typically carried by ocean currents and lack the ability to swim against them.
Question. What are examples of nekton organisms?
Answer: Examples include fish such as tuna and sharks, marine mammals like whales and dolphins, and some squid species.
Question. Why is nekton important for marine ecosystems?
Answer: Nekton species play a crucial role in the food chain by acting as both predators and prey, transferring energy through the ecosystem and maintaining ecological balance.
Question. How do human activities affect nekton populations?
Answer: Overfishing, habitat destruction, and pollution can lead to declines in nekton populations, affecting the stability of marine ecosystems and food webs.
MCQs
- Which of the following best describes nekton?
A) Organisms that float on the surface of water
B) Organisms that swim actively in water
C) Organisms that drift with currents
D) Only planktonic organisms
Answer: (B) See the Explanation
Nekton refers to organisms that can swim actively, such as fish and marine mammals, unlike plankton that are carried by currents.
- Which of the following is an example of a nekton organism?
A) Jellyfish
B) Phytoplankton
C) Tuna fish
D) Seaweed
Answer: (C) See the Explanation
Tuna fish are nekton organisms, as they are able to swim actively against water currents.
- How do nekton contribute to marine food webs?
A) By decomposing organic matter
B) By filtering water for plankton
C) By acting as both predators and prey
D) By photosynthesizing
Answer: (C) See the Explanation
Nekton are key components of the marine food web, both as predators and prey, transferring energy throughout the ecosystem.
- What is the primary difference between nekton and benthos?
A) Nekton live on the ocean floor, while benthos swim freely in the water
B) Nekton are passive organisms, while benthos are active swimmers
C) Nekton swim actively, while benthos live on or in the sea floor
D) There is no difference between nekton and benthos
Answer: (C) See the Explanation
Nekton are free-swimming organisms, whereas benthos are organisms that live on or in the ocean floor.
- Which human activity poses the greatest threat to nekton populations?
A) Ocean currents
B) Overfishing
C) Salinity changes
D) Natural predators
Answer: (B) See the Explanation
Overfishing is a significant threat to nekton populations, as it leads to population declines and disrupts the balance of marine ecosystems.
GS Mains Questions and Model Answers
Q1: Explain the role of nekton in maintaining marine ecosystem health.
Answer: Nekton organisms are vital for maintaining marine ecosystem health as they are integral to food webs, nutrient cycling, and ecosystem services. Their predation on smaller species regulates population sizes and their role as prey supports higher trophic levels, ensuring energy transfer through the ecosystem.
Q2: Discuss the impact of overfishing on nekton species and the broader marine environment.
Answer: Overfishing threatens nekton species by reducing their populations, which disrupts food webs and ecological balance. The depletion of key nekton species such as fish and marine mammals affects predators higher in the food chain, while also destabilizing the economic and ecological sustainability of marine environments.
Q3: How can conservation efforts help protect nekton populations?
Answer: Conservation efforts, including the establishment of marine protected areas, sustainable fishing practices, and pollution control, can help protect nekton populations. These measures ensure that habitats are preserved, species are allowed to recover, and the balance of marine ecosystems is maintained.
Previous Year Questions on Nekton
1. UPSC CSE 2019
Question: "Explain the role of marine biodiversity in the sustenance of marine ecosystems."
Answer: Marine biodiversity, including nekton species, plays a critical role in sustaining marine ecosystems by supporting food webs, nutrient cycling, and ecological balance. The health of nekton populations directly influences the stability of the entire ecosystem, contributing to the resilience and functioning of marine habitats.
2. UPSC CSE 2021
Question: "Discuss the threats to marine biodiversity and suggest measures to mitigate them."
Answer: Marine biodiversity faces threats from overfishing, pollution, habitat loss, and climate change. Conservation strategies like sustainable fisheries management, pollution control, and the protection of marine habitats through Marine Protected Areas (MPAs) are key to mitigating these threats and preserving biodiversity, including nekton species.
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