What is the difference between a food chain and a food web?

A food chain shows a single linear sequence of who eats whom; a food web shows the complex interconnected feeding relationships among many species in an ecosystem A food web is a simplified version of a food chain, used for teaching Food chains are used in marine ecosystems; food webs are used only on land They are identical concepts — 'food chain' and 'food web' are interchangeable

What is a trophic level?

A feeding position in a food web, from primary producers at the base to apex predators at the top The depth at which an organism lives in the ocean The amount of energy an organism stores in its body The geographic range of a species within its ecosystem

What is a trophic cascade?

When the removal or addition of a top predator triggers a chain reaction of changes through lower trophic levels, dramatically altering the ecosystem When a species migrates from one trophic level to a higher one as it grows The seasonal movement of nutrients from surface to deep water A rapid increase in plankton that feeds all higher trophic levels simultaneously

What type of symbiotic relationship describes clownfish living among sea anemone tentacles?

Mutualism — the clownfish gets protection from predators; the anemone benefits from the clownfish chasing away butterflyfish that eat anemone tentacles Commensalism — only the clownfish benefits; the anemone is unaffected Parasitism — the clownfish harms the anemone by stealing its food Competition — both species compete for the same food and space

What is commensalism in the ocean?

A relationship where one species benefits and the other is neither helped nor harmed — for example, remora fish attaching to sharks for transport and food scraps A relationship where both species compete for the same resources A relationship where one species benefits by harming the other A relationship where two species cooperate to hunt together

How do predator-prey population cycles work in marine ecosystems?

Prey populations grow when predators are few; predator populations then grow on the abundant prey, reducing prey numbers, which then causes predator numbers to fall — a repeating cycle Predator and prey populations always stay in perfect constant balance Predator populations grow first, then prey populations respond by growing faster Prey populations determine how many predators exist with no feedback loop

What is the 'ten percent rule' in ecology?

Only about 10% of the energy at one trophic level is transferred to the next — the rest is lost as heat, waste, and metabolic activity Ten percent of species in any ecosystem are producers Predators eat 10% of their body weight in prey each day Ten percent of ocean species are apex predators

What is an apex predator, and why does its presence indicate a healthy ecosystem?

An apex predator sits at the top of the food web with no natural predators; its presence indicates that enough energy flows through the ecosystem to sustain many trophic levels An apex predator is any large marine animal that eats fish Apex predators destabilize ecosystems by eating too many species An apex predator is one that can only be found at the deepest ocean depths

What is competitive exclusion in marine ecosystems?

When two species compete for exactly the same resources, the better competitor will eventually eliminate the other from that habitat When a predator removes all members of a competing prey species When ocean currents exclude certain species from reaching a habitat When pollution kills all species in a habitat simultaneously

What role do decomposers play in marine food webs?

They break down dead organic matter, recycling nutrients back into the water where they can be used again by phytoplankton and other producers Decomposers are not part of the food web — they only affect dead material Decomposers are apex predators that eat the largest dead animals They produce oxygen that sustains life in the deep ocean