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Subvert your cognition: How do bottom fish coexist with the mud and sand on the seabed?
Demersal fish, or what we call bottom fish, live mainly at the bottom of the ocean or lake, and this ecological area is called the demersal zone. They mostly live on sea and lake beds composed of mud, sand, gravel or rocks, and rely on food in the bottom environment to survive. The ecological habits of bottom fish not only make them an important part of the ecosystem, but also reveal how they survive in the seabed mud environment with different sediments.
Survival Adaptations of Bottom Fish
Demersal fish can be divided into two major types: strictly demersal fish and demersal pelagic fish. The main difference between the two is their level of contact with the seafloor and their buoyancy characteristics.
Benthal fishes are usually denser than in water and can easily rest on the seafloor. Their body structure is adapted to close contact with the seabed, and the mouths of many bottom fishes face downward, which makes it easier for them to prey on food hidden at the bottom.
Benton fish and bottom-dwelling pelagic fish
Benth-dwelling fish, such as flounder and stingrays, usually sit quietly on the seabed waiting for prey to arrive, or actively search for food. Demersal pelagic fish live in the water layer close to the seabed and rely on food such as benthic organisms and plankton for survival. The existence of these fish not only enriches the marine ecology, but also has a certain sensitivity to environmental changes.
Operation mechanism of the underlying ecosystem
In an environment where bottom fish coexist, the presence of mud and sand is inevitable. These fish must develop specific mechanisms to adapt to the bottom environment and avoid ingesting too much sediment. When feeding, many bottom fish will expel excess sand through their gill slits to keep their feeding process going smoothly.
Most bottom fish have flat bellies, allowing them to rest easily on the seafloor. The specialized mouth structures of bottom-dwelling fish help them more effectively hunt for organisms lurking beneath the sand.
Special case: Flatfish
Platanus is a typical bottom-dwelling fish. Adult fish have two eyes on one side of the head, which is a change during its growth process. As they transition from juvenile to adult stages, many species have one eye migrated to the other side, which helps them better navigate the seafloor and hunt for food.
Habitat and distribution
The ecological distribution of demersal fish is closely related to the characteristics of the seabed where they live. Along the edge of the continental shelf, the bottom habitat will be more diverse, allowing these fish to thrive in waters between five and two hundred meters deep. These habitats also attract many other marine life, forming a rich ecosystem.
With increasing depth, the amount and diversity of bottom-dwelling organisms change gradually. In deep-sea ecosystems, bottom fish may adapt to challenging conditions with fewer food sources.
Business and conservation challenges
When it comes to harvesting groundfish, there is tension between the demands of commercial fisheries and the need to conserve these species. As the impact of human activities intensifies, many once abundant bottom fish species have shown a downward trend, which worries scientists and environmentalists.
Many groundfish, such as cod and flounder, are already listed as below safe biological limits, making recovery more difficult.
Future Outlook
After discussing the survival skills of bottom fish and how they coexist with mud and sand, we can't help but wonder: As human activities increase the impact on the environment, what can we do to protect these mysterious and important seafloor What about the residents?
