Symbiosis is the interaction between two different organisms living in close physical association. 3 types we will discuss:
Mutualism - beneficial to both organisms involved. Ex: bee pollinates flowers, and the flowers feed the bee
Parasitism - one species, the parasite, benefits while the other species is harmed (host). Ex: flee feeding on a dog
Commensalism - one species benefits, while the other is neither harmed nor helped. Ex: bison walking through grass, which stirs up insects for birds to eat. The bison is not getting anything out of this relationship, but is not harmed either. The bird to getting easy to catch insects.
Practice Problems
Identify the following relationships as either mutualism. parasitism, or commensalism.
1. Oxpeckers feed on ticks found on the back on rhinoceros.
2. Ants protecting the acacia trees and the acacia trees feeding the ants.
3. The Honeyguide, a bird, and the badger both eat honey. The Honeyguide connot open a beehive and the badger connot find the hive. The Honeyguide leads the badger to the hive and the badger breaks open the hive so both can eat the honey.
4. A cymothoid isopod lives inside the mouth of a snapper fish. The isopod severs (cuts) blood vessels in the fish's tongue, causing the tongue to atrophy and degenerate (break down). The isopod then hooks its pereopods, or legs, to the base of the fish's tongue, essentially replacing the tongue. The isopod stays there for the rest of its life, feeding on blood, mucus, and stray pieces of food from the fish.
5. An alpheid shrimp digs and maintains a deep burrow. While underground, the shrimp is safe. Above ground, it is vulnerable to predators. A goby fish lives in the burrow with the shrimp. The goby fish sits at the enterance, keeping watch for predators, and signals the shrimp with a flick of its tail when it is safe to come out. Or, if the predator swims by, the goby darts into the burrow and the shrimp retreats further inside. These two animals are completely dependent on each other - the goby benefits by getting a burrow to live in and the shrimp knows when prdators are near.
6. Some species of barnacles attach themselves to sea turtles or whales. As the whale or sea turtles travel, the barnacles gain access to food in nutrient-rich waters. Their hosts neither benefits nor is harmed by its riders.
7. Ants have farmed fungi for millions of years - weeding, mulching, fertilizing crops, in a sheltered underground nest, feeding chewed up leaves. The fungus is the only food the ant eats.
8. A cuckoo may lays its eggs in a warbler's nest. The cuckoo's young will displace the warbler's young and will be reaised by the warbler.
9. When a crocodile feels the need for a good teeth cleaning it will sit with its mouth wide open. The Egyptian plover bird sees the invitation, and if one is nearby, it will fly into the mouth of the crocodile, eat the food stuck in its teeth, and fly away unharmed.