Seen here perched on the head of a primate, the African oxpecker was thought to be friendly tick-eating helper, but is actually a vampire bird, sucking blood out of open tick-wounds.
Credit: Wikimedia
SYDNEY: There are many cases in nature where species team up to help each other, a behaviour known as symbiosis. Resources or services that may be scarce for one organism may be cheap and easy for another to provide.
Biologist Cameron Currie from the University of Wisconsin in Madison, USA, cites bacteria cosily dwelling inside humans as a classic example. "Our own bodies have hundreds or even thousands of species of symbiotic microbes inside them - we couldn't survive without their beneficial effects," he said.
SEA ANEMONES AND HERMIT CRABS
Sea anemones (Calliactus spp) hitchhike on the back of hermit crabs, scoring a ride across the seabed and extending their tentacles to eat the crab's leftovers. Crabs actively recruit these passengers. After poking an anemone with its pincers - causing it to release its grip from its current home - the crab holds it in place so the anemone can reattach to the crab's own shell.
In return, the anemones fend off hungry octopuses and other predators using their barbed tentacles. The crabs return the favour by driving away creatures that eat anemones, such as starfish and fireworms.
GOBY FISH AND SNAPPING SHRIMP
Danger! That's what the frantically flapping tail of a goby fish says to the near-blind snapping shrimp (Alfeus spp). In a crafty collaboration, snapping shrimps construct and maintain burrows in the seabed, while the fish stands guard. During construction, shrimps leave the burrow to deposit excavated sand.
Throughout this hazardous venture, shrimps maintain constant contact with their gobies using their antennae. In some cases, gobies even hover above their shrimp, allowing it to take its load further from the burrow's entrance. Sighting potential threats, the fish waggles its tail against the shrimps' antennae or into the burrow entrance, warning the shrimp of the danger. In return, the fish can call the burrow home, sleeping in it with the shrimp at night and using it as a convenient bolthole in the face of peril.
AFRICAN OXPECKERS
African oxpeckers (Buphagus africanus and Buphagus erythrorhynchus) feed on the backs of zebra, elephants, hippopotamuses and other large African animals. Once thought to be friendly tick-eating helpers, they're actually vampire birds, sucking blood out of open tick-wounds. This shows how the line between symbiotic assistant and parasite can be blurred. Oxpeckers do eat ticks as well, and some animals may be happy to sacrifice a bit of blood for this service. Oxpeckers may also be tolerated because they produce a hissing scream when startled - like a personal danger alarm.
CELLS AND MITOCHONDRIA
Over a billion years ago, one type of bacteria ate another - or tried to. Surviving this ordeal, the prey became a permanent house guest in the wet, sheltered, food-rich environment of the predator's body. Like an internal battery, the smaller bacteria adapted to turn food and oxygen into chemical energy for the larger one.
Eventually, by swapping segments of DNA, the two bacteria merged into a single, inseparable, complex cell. This ultimate partnership is the ancestor of all multicellular life, including our own species. These mitochondrial descendants of bacterial ancestors power each and every cell in our bodies.
