Predator and Prey Relationships

Definition of predator review: 1) We are also predators when we hunt, fish, or buy meat or vegetables from the grocery store. 2) Not all predators are carnivores- also herbivores and carnivorous plants 3) Not all prey die as a result of predation (ex: salamanders’ tails & starfish regeneration.)

How do predators increase their chances of getting a meal? Herbivores- simply walk, swim, or fly up to their plant prey. Carnivores- feed on mobile prey so have 2 options: –Pursuit: generally fast paced. –Ambush: generally slow paced.

The thrill of pursuit…. Cheetah- catch prey by being able to run very fast. American bald eagle- fly and have keen eyesight. Wolves and African lions- cooperate by hunting in packs. Humans- invented tools (weapons & traps) to capture prey.

The patience of ambush…. A stationary frog ambushes flying insects by flicking out its long, sticky tongue. Spiders and praying mantises sit in flowers that match their color and ambush visiting insects. A lion’s coloring allows it to blend in with savanna grass so it can get closer to its prey. The alligator snapping turtle lies camouflaged in a stream- bottom and dangles its worm-shaped tongue to entice fish into its powerful jaws. Drops of sticky digestive fluid which look like pollen hang from the tentacles of a carnivorous sundew plant.

How do prey defend themselves against predators? Prey species have evolved various protective mechanisms, otherwise they would easily be captured and eaten. Some can run, swim, or fly fast; some live in large groups; others have highly developed sight or a sense of smell that alerts them to the presence of a predator. Others have a protective shell, thick bark, spines, thorns, camouflage, use chemical warfare, warning coloration, mimicry or behavioral strategies.

Warning coloration on a poison dart frog sends a signal to experienced predators not to eat its poisonous flesh (skin oozes one of the strongest poisons known.)

The viceroy butterfly (right) gains protection by looking like the poisonous monarch butterfly (left).

Protective shells Most mollusks Armadillos Crabs Turtles Corals Exoskeletons

Spines, thorns, & thick bark Spines in porcupines Thorns in cacti and rosebushes Some insect species have evolved shapes that look like twigs (stick caterpillars), thorns (treehoppers), dead leaves, or bird droppings on leaves.

Chemical Warfare! Some prey species discourage predators with chemicals that are poisonous (oleander plants), irritating (bombardier beetles), foul smelling (skunks, skunk cabbages, stink bugs), or bad tasting (buttercups and monarch butterflies). To date, scientists have identified over 10,000 defensive chemicals made by plants including cocaine, nicotine, caffeine, cyanide, opium, strychnine, peyote and rotenone (insecticide).

When a bombardier beetle is assaulted by an ant, it defends itself by spewing out a boiling hot irritant from special glands.

When touched, the snake caterpillar alters its body shape to look like the head of a snake and “strikes” at whatever touches it.

Senses of Prey Left-brained versus right-brained animals? Predators are primarily left-brained, or responding, animals. This means they take time, access information and somewhat figure things out. Prey animals are instinctively right-brained, or reacting animals. This means they run from all new situations until they can get the situation categorized as a real danger or a non-danger.

Average senses versus keen senses? Predators have keen senses, but prey animals must have extremely keen senses to forewarn them of danger before the danger gets within striking distance.

Predator/Prey Evolution Galapagos tortoises eat the branches of the cactus plants that grow on the Galapagos Islands. On one of the islands, where long-necked tortoises live, the branches are higher off the ground. On another island, where short-necked tortoises live, the branches are lower down. The cactuses, the prey, may have evolved high branches so that the tortoises, the predators, can't reach them.

Can Animals Sense Natural Disasters? Animals have keen senses that help them avoid predators or locate prey. Senses might also help them detect pending disasters. There are two theories as to how animals may be able to detect earthquakes. –One theory is that animals sense the earth's vibrations. –Another is that they can detect changes in the air or gases released by the earth. Scientists- what would they think?

There has been no conclusive evidence as to how animals may be able to sense earthquakes. Some researchers believe the animals at Yala National Park were able to detect the earthquake and move to higher ground before the tsunami hit, causing massive waves and flooding. Researchers around the world are continuing to study animal behavior and earthquakes. It is hoped that these studies will help to aid earthquake predictions.