Humans have evolved over millions of years to help each other. Finding food, building shelters, and protecting the young, for example. There are many reasons a symbiotic relationship is valuable. Humans are not the only species to help one another. Many animal species are symbiotic, helping each other.
Animals have symbiotic and altruistic relationships with their own and other species. Many animals will look after others of their own species to ensure their survival. Watching out for predators and sharing food is a couple of the ways they can do this. However, many species, such as humpback whales, will protect other species, even though it serves the whale no purpose.
While inter-species symbiosis is expected (the same species), cross-species symbiosis is also frequently observed. It may not seem advantageous for two different species to help each other, but a partnership can be beneficial for many reasons.
Symbiosis and Altruism
The term ‘symbiosis’ refers to a relationship between two distinctly different species. Corals and fish are perhaps the best-known examples of a symbiotic relationship. Corals and fish both benefit equally from the relationship, gaining protection and food. Many fish depend on corals for habitat and food, while corals need fish to help them reproduce.
The benefits of a symbiotic relationship ensure the continued survival of both species, without any harm being caused to either side.
Some relationships are altruistic, meaning only one individual benefits. This is usually observed with one species protecting another from a predator, even when there is no obvious benefit to the animal doing the protecting.
Scientists have observed humpback whales in Canadian waters, protecting seals from pods of orcas. There is no benefit to the humpback whales offering seals protection, and it is not yet known why they do so.
It is theorised that some species, such as dolphins and whales, have a much more complex cognitive ability than previously thought.
Animals within the same species would be expected to help one another, especially if they are pack or herding animals. Sometimes, a group will accept a lone animal into their group. But how is this beneficial?
You may notice this behavior at the dog park. When a scuffle breaks out, there is usually one dominant dog who immediately runs over to break up the fight. It may appear as though this dog is attempting to join in, but the reality is that this dog is trying to defuse the situation and prevent physical injury.
Dogs like order, and each group will have a hierarchy. There is always a dominant dog who watches the group and will growl or snap at any dogs who take playtime too far. This behavior ensures that every dog in the group is safe and injuries do not occur.
Herding animals such as sheep, goats, and deer will help each other to feed. While some members of the group will be grazing, other members will keep watch for danger. The grazing members will then swap, so the rest of the group also get time to eat.
Rabbits and hares have a similar living situation. There will also be group members on watch, and if they sense danger, they will stamp their feet on the ground to warn the rest of the group to find shelter.
Many bird species also adopt this same approach. Being able to fly has its advantages, but sometimes a bird’s predator is another bird. If one bird spots a predator, they will give a warning call and take off. This prompts the rest of the group to take off as well.
A predator may be intimidated by a large flock all taking off at once, so this behavior reduces the risk of predation.
It does not matter whether the species is carnivorous or herbivorous; groups will always help each other to protect their young. This may be from lone animals or predators.
Herds and packs will also ensure food is available for the young in the group, even if it means the adults get less food. Predators typically try to catch larger prey when there are babies in the group.
Some species will have a relationship that benefits both species, whereas others have a relationship that only satisfies one. Scientists are still working to determine the reason for this kind of behavior when there is no evident payoff for providing help or protection.
The best example of cross-species symbiosis is fish and corals. The John Pennekamp coral reef state park is North America’s only coral barrier reef.
The underwater national park is roughly 220 square miles and home to more than 260 fish species. These fish share a symbiotic relationship with the 80+ coral species. This is a mutually beneficial situation. The fish provide the corals with beneficial bacteria from the waste they produce. Many of the fish feed on seaweed, which prevents the coral from losing valuable space and sunlight.
In turn, the corals provide the perfect hiding spots from predators like barracudas, and they are also great nurseries for newly hatched fish.
On land, there are many similar examples. Fur-covered mammals such as deer are often seen with birds on their backs. It may seem as though the birds are just hitching a ride, but there is something more going on.
The deer’s fur is home to many parasites such as fleas and other insects. Naturally, this is irritating to the deer, causing itchiness and skin sores. Birds such as starlings have adapted to feed off these insects as they are an easy meal. The birds do not need to expend any energy to catch them. So, both species benefit.
Scavenger species such as vultures and coyotes benefit from the death of other animals, as their carcass provides the scavengers with food. Coyotes and vultures are often seen near one another, especially if there is a sick or injured animal nearby.
From large animals to tiny, insects help each other too. Ants and aphids have a mutually beneficial relationship. Aphids secrete honeydew, a carbohydrate-rich liquid that ants feed off. In turn, the ants herd the aphids in groups to protect them from predators and preserve their food source.
As already mentioned, whales have been known to protect seals from being attacked, but dolphins are also documented protectors. Many fishermen have witnessed dolphins helping other animals avoid sharks or attempting to free animals from fishing nets. There is no benefit to this behavior, but the dolphins are still driven to help a distressed animal.
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