Examples of Commensalism

They say man is a social animal. And to survive in this world, he must maintain a stable relationship with all other species. But have you ever thought of what are the various relationships that different animal species share with each other? There are many relationships that many species share with each other, depending on various factors like where they are in the food chain, their habitat, etc. One such relationship is commensalism. So, what is commensalism? Commensalism comes from the English word 'commensal' which means 'sharing of food'. In simple words, the definition of commensalism would be the relationship between two organisms, wherein one organism benefits while the other remains unaffected. It is one of the types of symbiotic relationships, the others being mutualism and parasitism.

Commensalism Examples

• One of the best examples would be the relationship between cattle egret and cows and sheep (or cattle). The cattle egret is called so because it is often seen with cattle and livestock. Whenever horses, cows and other such livestock graze in fields, they tend to stir up and move many insects that have been resting on the grass. The cattle egret then catches them and preys upon them. The cattle egrets benefit from this because they manage to get the insects that they wish to prey on whereas the cattle remains unaffected.
• One of the examples in the ocean is seen in sedentary crustaceans known as barnacles. These are very sedentary crustaceans, and so, they usually attach themselves to a substrate in the sea like rocks or preferably whales, seat turtles, etc. When whales and such creatures travel, the barnacles get access to nutrient rich waters and often, the morsels of food that are left behind by the whale, the barnacle catches it and eats it. These barnacles do the same thing when they attach themselves to the bodies of green sea turtles.
• Another commensalism example that is commonly seen is the desert holly shrub which provides shade for growing creosote bushed beneath it. Also, another example of commensalism in the desert is where the fringe toed lizard stays in an abandoned desert rat hole.
• If you thought that the tundra region was devoid of any commensalistic relationships, then think again! One of the examples of commensalism in the tundra biome is between the caribou and the arctic fox, wherein the fox tends to follow the caribou while it is on the prowl. The caribou tends to dig in the snow to get its food, which is in the form of lichen plants. Once it digs up the soil, then the arctic fox comes and hunts some of the subnivean mammals that have come closer to the surface due to the digging action of the caribou. Thus, the caribou remains unaffected, whereas the arctic fox benefits from its actions. Surely, one of the interesting tundra facts!
• The relationship between Remora sharks and whales is yet another example, wherein Remora sharks have an adhesive disk on their dorsal surface, with the help of which they attach themselves to whales and then, feed on the remains from the whale's food.
• Commensalism is also seen between birds that follow army ants, wherein the army ants stir the flying insects resting on the ground and then, the birds catch and eat them. Commensalism is also seen between the Monarch butterfly and the Viceroy butterfly. Monarch butterflies contain cardiac glycosides, which are poisonous to vertebrates, so frogs and other vertebrates that prey on butterflies do not eat the Monarch butterfly. However, the Viceroy butterfly does not contain cardiac glycosides, but still, mimics the Monarch butterfly, due to which it manages to escape the prey. Thus, the Monarch population of butterflies remain largely unaffected by the Viceroy butterflies, whereas the Viceroy butterflies tend to benefit by mimicking the Monarch butterflies

These were some commensalism, or symbiotic relationships examples. There are a few examples of commensalism relationships in humans too. There are millions of bacteria found on the skin, but not all of them harm and in fact, we are left unaffected by them, whereas they get shelter due to our skin. In the end, it is all these relationships that all species share which makes the interesting science known as biology or life sciences!