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A top-down cascade is a trophic cascade where the top consumer/predator controls the primary consumer population. In turn, the primary producer population thrives. The removal of the top predator can alter the food web dynamics. In this case, the primary consumers would overpopulate and exploit the primary producers. Eventually there would not ...
The original idea that carp could be cultured most likely arose when they were washed into ponds and paddy fields during monsoons. This would lead naturally to the idea of stocking ponds. [17] The Chinese politician Fan Li was credited with authorship of The Fish-Breeding Classic, [18] the earliest-known treatise on fish farming.
Seafood is any form of sea life regarded as food by humans, prominently including fish and shellfish.Shellfish include various species of molluscs (e.g., bivalve molluscs such as clams, oysters, and mussels, and cephalopods such as octopus and squid), crustaceans (e.g. shrimp, crabs, and lobster), and echinoderms (e.g. sea cucumbers and sea urchins).
The bony fish evolved into two separate groups: the Actinopterygii (or ray-finned fish) and Sarcopterygii (which includes the lobe-finned fish). During the Devonian period a great increase in fish variety occurred, especially among the ostracoderms and placoderms, and also among the lobe-finned fish and early sharks.
Secondary consumers are small/medium-sized carnivores that prey on herbivorous animals. Omnivores, which feed on both plants and animals, can be considered as being both primary and secondary consumers. Tertiary consumers, which are sometimes also known as apex predators, are hypercarnivorous or omnivorous animals usually at the top of food ...
A freshwater aquatic food web. The blue arrows show a complete food chain (algae → daphnia → gizzard shad → largemouth bass → great blue heron). A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community.
The evolution of fishes took place over a timeline which spans the Cambrian to the Cenozoic, including during that time in particular the Devonian, which has been dubbed the "age of fishes" for the many changes during that period. The Late Devonian extinctions played a crucial role in shaping the evolution of fish, or vertebrates in general. [1]
That is, the consumer trophic level is one plus the weighted average of how much different trophic levels contribute to its food. In the case of marine ecosystems, the trophic level of most fish and other marine consumers takes a value between 2.0 and 5.0.