There is a Chinese proverb which says, "Get together is nice, live together is tough." Clashes between two buddies from different backgrounds living together could drive them apart. This would not happen to animals which cohabit, not to make friends, but for the purpose of survival and species propagation. The symbiotic alliance of different species cohabiting is not only strong but also fascinating.
Fish-Shrimp Cohabitation
Gobies and pistol shrimps cohabit in the Indian Ocean and nearby regions. They are friendly "symbiotic roommates". The goby has excellent eyesight while the pistol shrimp is almost blind. The former cannot dig while the latter is a natural burrower. They complete each other.
The pistol shrimp has a big claw that is as efficient as the blade of a bulldozer for digging. It shares the burrow with the goby and maintains its upkeep. The goby acts as a bodyguard to ensure the safety of the near-blind pistol shrimp in return for the shelter.
The pistol shrimp stays in constant contact with the goby by placing one antenna on the fish. When the goby detects danger, the reliable bodyguard will alert the shrimp to dart back to the burrow with specific tail movements and chemical signals.
The couple forages as a compatible pair. The goby feeds on small animals disturbed by pistol shrimp's burrowing and the latter scavenge on the detritus of the former's meals. The pistol shrimp also feeds on the algae growing on rocks. If the algae are washed away, the goby even helps the shrimp retrieve them!
Ants-Aphids Cohabitation
Cohabitation between ants and aphids is a unilateral agreement unlike the equitable goby and pistol shrimp partnership.
Aphids feed on plant saps and excrete honeydew, a sticky sugary liquid that is nutritious food for ants which would park right next to them for unlimited honeydew freeflow. Provision of honeydew excrement is a service welcomed by aphids in exchange for protection from predators like ladybirds and parasitoid wasps.
But some ants would "abduct" aphids to their nests to assure non-stop honeydew supply. So much for consent! Worker ants would carry aphids to juicy parts of plants such as underleaves or young shoots to facilitate sap-sucking during the day and bring them back to ant nests at night. Sometimes, aphids are left outdoors by worker ants until winter comes.
Keeping aphids as companions is like having an all-you-can-eat buffet round the clock. But if aphids cannot produce enough honeydew, ants will not hesitate to have their companions for dinner.
Bighearted Cohabitation
The Australian Bare-nosed Wombats (Vombatus ursinus) have played host to 19 species of mammals, 33 species of birds and 4 species of reptiles, a record of 56 species of animals in total. Peaceful communal living with so many species is a true example of compassion.
However, this is only a rarity during wildfires. The "shared flat" is in fact a massive network of burrows.
Wombats are territorial and aggressive towards intruders. They are avid diggers. Their burrows form well-connected warrens which can have as many as 20 to 30 entrances and measuring about 100 metres in length.
In the 2019-2020 wildfires in New South Wales, Australia, wombat warrens became a safe haven for a large number of animals. In the wake of wildfires, researchers found that a total of 56 species of animals had moved in to Bare-nosed Wombat warrens at different times for a makeshift "house sharing".
