FishPredation

Fish Predation

Common Methods

• Stalking
• Chasing
• Ambush
• Habituation
• Angling

Predation Model

 

A clingfish in the Caribbean exhibits camouflage.

Some fish, such as the porcupine fish, have defense mechanisms to avoid capture.

Fish often travel in schools to avoid predation.

• Energy vs. Cost
• Factors Affecting Search:
  • For Predator: Hunger
  • For Prey: Camouflage
• Factors Affecting Encounter
  • For Predator: Swimming Speed, water clarity, illumination, schooling, detection mechanisms
  • For Prey: morphology, activity level, pigmentation, distribution
• Factors Affecting Strike
  • For Predator: alternative prey, location
  • For Prey: body size, sensory ability
• Factors Affecting Capture
  • For Predator: mouth gape, strike speed, handling
  • For Prey: escape capabilities, schooling, shelter seeking behavior

This diagram shows the factors that affect juvenile feeding behavior.

Other Feeding Factors

Juvenile fish are the most susceptible to predation.

In the Caribbean, the lionfish is an invasive predator. Invasive species can alter the food web.

Size is the most important factor in determining predation rates. For example, there is a decreasing rate of predation with jellyfish as fish larvae size increases. One fish that is commonly found in the Caribbean, the porcupine fish, inflates its body in order to increase its size, therefore decreasing the predators that would be capable of eating it. Predators would have to have a larger jaw in order to eat the porcupine fish. Predation occurs at all size of organisms. Microscopic organisms are predators, and so are large whales. The highest rates of predation occur on juvenile fish. This is because predation is most common during life transitions. After fish larvae hatch, the are more susceptible to predators. Fish are also susceptible to predator at another life transition- during mating. Most fish are active either during the day or at night, not 24 hours. Their diurnal or nocturnal feeding is normally fixed genetically.

Importance of Predation

Food Web

Predators help keep the food web in-check. Food webs are divided by trophic levels. Top predators have “trophic cascade” effect on food webs- having a top-down effect on lower trophic levels. The elimination of predators can cause serious perturbations to an ecosystem.

Nurse sharks are a common predator in the Caribbean. They are bottom-feeders.

Important Evolutionary Force

Predation is a strong force of natural selection. The weaker species is eliminated. Fish Predation is an important evolutionary force because when certain types of fish are targeted by predators they do not have as great of a survival rate. They are either forced to acclimate and as numbers dwindle and the more advantageous fish win out, and the fish population will evolve over time.