RELATIONSHIPS BETWEEN LIVING THINGS IN THEIR HABITAT

An Ecological relationship is the relationship between organisms in an ecosystem. All organisms in an ecosystem are connected. Each interaction depends on the one before it. Each population interacts with one another in a complex web of relations. Ecological relationships help better describe how they are connected.

There are six ecological relationships of which two are oppositional and four are symbiotic. The oppositional relationships are predation and competition. The symbiotic relationships are mutualism, commensalism, amensalism, and parasitism.

The ecological relationship an organism has depends on the way the organism adapted to its environmental pressures on evolutionary bases.

Oppositional relationships

Predation

This is where one organism hunts and eats the other organism. The organism hunting is called the predator, while the organism being hunted is called the prey. Energy received from the sun is transferred from animals when the prey is eaten by the predator. The predator now has its prey’s energy.

A predator is usually a carnivore that hunts, kills, and eats other animals. For example, a snake eating a mouse, the snake is considered the predator because it is consuming the mouse. In another example, a striped marlin is a predator. It lives in the Pacific Ocean and preys on sardines, also a Pacific animal. Similarly, various birds eat earthworms.

However, a predator can become the prey of another larger predator. For instance, a snake may become a meal for a hawk.

“In ecology, predation is a mechanism of population control. Thus, when the number of predators is scarce, the number of prey should rise. When this happens, the predators would be able to reproduce more and possibly change their hunting habits. As the number of predators rises, the number of prey declines. This results in food scarcity for predators that can eventually lead to the death of many predators.”

Because of this, predation is called a “positive-negative” relationship.  There is also Cannibalism. It is a higher grade of predation. This is where in one population the organisms eat each other because of the scarcity of food sources.  Ex. Frogs are known for cannibalism too.

Herbivore/plant predation

The prey does not necessarily have to be an animal, but can also be a plant. When the prey is a plant, the relationship would be called an herbivore-plant relationship.

A perfect example of this would be,” Galapagos tortoises and cactus plants that grow on the Galapagos Islands.” 

Another example is the koalas. They have a special digestive system that allows them to break down tough eucalyptus leaves and remain unharmed by their poison (National Geographic).

Finally, a squirrel is the herbivore (predator) and the nuts he eats are the plant (prey).

Food Webs 

The species that make up an ecosystem are connected in complex “food webs” of the eater and eaten. Food webs show interconnectedness, especially between predators and their prey.

When one species disappears, its predators can no longer eat it and its prey is no longer eaten by it. Changes in these populations affect others.

Energy Pyramids 

An energy pyramid is a way of showing how energy flows through an ecosystem specifically on a certain food chain (predators and their prey).

Energy – The energy for all living things comes from the sun

Producers – Plants that capture the light energy and turn it into chemical energy (stored in sugar)

Consumers – Organisms that can’t make their food 

Carnivores – Consumers that eat animals 

Example. Lion eat Zebra

Herbivores – Consumers that eat plants (producers) 

Example. Chipmunks and Armadillos

Omnivores – Consumers that eat both animals and plants 

Example. Badgers

Scavengers are consumers who eat dead animals 

Example. Vultures

Decomposers are consumers who eat and/or break down waste products 

Example. Fungus and Mold

Competition

Competition is when organisms compete for the same resources. This is a negative relationship because both organisms are harming each other (Campbell).

Intraspecies competition

Organisms competing can be from within the same species, for example, two male elk fighting for a female mate. Elephants also fight each other so that the dominant elephant will get to breed with the female.

Another species that shows great competition between each other is the dolphin. Dolphins go along together and play with each other, but when it is time to eat; all dolphins have to compete for a meal.

Interspecies competition

Competition can be also found in two different species. A lizard and a frog can compete for a similar food they eat such as a small insect. This type of competition is only found when two different species share an ecological niche that they must compete over.

Competitive exclusion principle

“Direct competition between different species almost always produces a winner and a loser- and the losing species dies out,” or is forced to migrate to another ecosystem that can support them (Levine, 2010). This is the competitive exclusion principle. This principle says that two species that need the same resources cannot survive together in the same habitat. One organism will eventually die off, thus, Symbiotic relationships.

Mutualism 

 Mutualism is a relationship in which organisms benefit from each other. This is a positive, positive relationship. 

An example of this would be the bee and flower. Bee gets nectar and honey from flowers. The bee contributes back to the flower by spreading the pollen so that the flowers can reproduce. This is a very common contribution to both the flower and the bee, they both rely on each other to survive. 

Another example would be when the ox pecker lands on an impala’s back and eats the ticks that are a parasite to the impala. The oxpecker is benefited because it gets a meal from the tick and the impala gets benefited because the tick is no longer on it. Similarly, monkeys pick fleas from other monkeys which benefits both because it’s like a treat.

There is a mutualistic relationship between spider crabs and algae. The algae live on the crabs’ backs, allowing the spider crab to blend in with its environment so that predators can’t find them. The algae get a nice place to live, while in turn, the spider crab gets camouflaged. Thus, both organisms are benefited.

The Clownfish and Anemone would also be a good fit for mutualism because the Anemone protects the clownfish while the clownfish protects the Anemone. “The clownfish benefits by having a protected home territory.” 

Finally, there is even a mutualistic relationship within the human body. Bacteria live inside our intestines (getting a good place to live) and help us break down our food and get vitamins.

Commensalism

Commensalism is a relationship in which one organism benefits from another organism that is not affected. This is a positive, neutral relationship.  

For example, a small fish called the Pilot Fish follows underneath a shark, and when the shark eats something the pilot fish eats the scrap pieces of the shark’s original kill. (Blue Planet BBC Documentary 2001).

Another example is a bird’s nest in a tree. The bird is benefitting because the tree is giving the bird shelter and the tree is not getting anything in return.

Similarly, the transparent shrimp benefits from a reef because it hides within it (camouflaging), but the coral is not affected.

Additionally, the relationship between an infectious disease and its carrier, an animal such as a mosquito, could be classified as commensalism because the mosquito is unaffected by the presence of the disease, but the mosquito transfers it to a host in which the disease can reproduce or spread more easily to others.

“Often, the host species provides a home and/or transportation for the other species.) The whale and barnacles are a perfect example of this. “Barnacles are crustaceans that have jointed legs and shells of connected overlapping plates. Instead of crawling after food, they glue themselves to rocks, ships, pilings, abalones, and maybe even whales and wait for food to wash by. The barnacles attach themselves to the whale. This way, the barnacle can get food faster. This does not affect the whale so he does not take the barnacle off.

Parasitism 

Parasitism is a relationship in which one organism (the parasite) benefits while the other(the host) is harmed. This is a positive, negative relationship. 

The parasite usually lives on or inside the other organism.

For example, mosquito is a parasite, feeding on a human while transferring the disease called Malaria. Other examples would be ticks or fleas that live off of many large mammals. Similarly, head lice are an example of parasitism because they feed on blood from the human head.

In Colorado, the pine bark beetle is a common parasite. The pine beetles lay their eggs in the pine trees, and then when the babies are born, they eat the layers of the tree which stops the tree from growing. 

“Natural Selection favors parasites that are best able to locate hosts and feed on them”’