The Science of A Perfect Partnership | Teachings from the Crab and the Sea Anemone

Relationships should be a source of mutual support, respect and cooperation. More often than not, they end up being—or becoming—battlegrounds where individuals, corporations and even countries find themselves protecting their own interests at someone else’s expense.

On average, we humans are takers—not givers. The overexploitation of the natural resources of the world is a case in point.

We believe we live in a big-fish-eats-little-fish world that’s characterised by the predator-prey relationship. When we speak of the food chain, we focus on who eats who in the circle of life. Animal documentaries—more often than not—focus on hungry animals on the prowl for a prey.

Is that the only type of relationship that characterises our short-lived lives on earth?

The answer is a resounding no.

As someone who’s loved the ocean for as long as I can remember, I find more answers to life’s big questions when I look under the sea as opposed to life on dry land. The sea has long been a metaphor for the subconscious mind and when we plunge into its depths, we find answers that surprise and astound us.

The Hermit Crab and The Sea Anemone

A couple of years ago, I grew extremely fascinated by the relationship between the hermit crab and the sea anemone. The two animals are virtually inseparable. Besties, if you will. Theirs is a symbiotic relationship where they cohabitate in harmony together. It’s a seemingly stable connection that sidesteps the prey-predator relationship that is characteristic of the food chain where big-fish-eats-little-fish.

The sea anemone eats scraps of food that the messy eater the hermit crab leaves behind as she eats. In return, the sea anemone provides the hermit crab with protection from predators like the octopus. The sea anemone is a vigilant companion that will threaten anyone who dares to get too close–with the painful sting of its tentacles. Unlike other crustaceans, whose bodies are hard and calcified; most species of the hermit crab have long, spirally curved abdomens, which are soft and vulnerable.

Unlike crabs, that sidestep their way through life, sea anemones are largely immobile. Hitchhiking on a hermit crab’s shell allows the anemone a much-larger stomping ground to forage for food. While the duo are sightseeing under the sea, the anemone traps and collects plankton and small fish. Unlike the tortoise and the turtle, who are born blessed with a home that they can carry on their backs, crabs rely on the sea anemone to provide them with a much-needed abode that protects them from the fish-eat-fish world.

The Ocean Real Estate Market for Renters

Unlike other animals which partner for life (or other animals that display polygamous partnerships), the sea anemone’s relationship with the crab is one that is shared by all members of the two species. Once a crab outgrows—and I mean this literally—a particular sea anemone, the crab leaves it behind for another member of its extended family to pick up. Unsurprisingly, the sea anemone does resist and fight as it is pried away from its best friend—but it eventually acquiesces.

For the symbiosis to be a true partnership, both the sea anemone and the crab must be able to reciprocate. The hermit crab needs to be able to choose a home that is neither too small nor too large for its size.

Based on this, it may be tempting to conclude that the relationship between the sea anemone is a short-term romance. But my own observations lead me to believe that the symbiosis here is between the species; as opposed to an exclusively monogamous relationship between a specific crab and a specific sea anemone.

After a short tug-of-war, the sea anemone accepts that the crab has simply grown too big and needs a new home.

So the crab transfers itself to its new home, leaving the old anemone for one of his brethren to pick up. However— do not think for one moment that the sea anemone has been broken-up with or abandoned. Suitable homes for hermit crabs can be a limited resource; and competition does occur among hermit crabs for rental properties. After all, the real-estate availability at any given time is largely dependent on prevailing market conditions.

Much like the rest of us in the animal kingdom, hermit crabs have been known to fight or kill a competitor to gain access to the partner they favour. If, however, the crabs vary significantly in size, the occurrence of fights decreases or remains nonexistent.

Hermit crabs who live in homes that are too small for them cannot grow as fast as those with well-fitting shells—and are more likely to be eaten if they cannot retract completely into their rental property. Crabs also tend to stay away from shells that are too big for them, leaving the house open in the market for a more suitable match.

Crabs are renters, not owners. They do not believe they own the sea anemone—and vice versa. As humans, there are those among us who are motivated by an insatiable greed to own, to hoard and not to share. The crab and the sea anemone teach— and remind us—that we are here on borrowed time.

We can fight and compete to meet our needs; but we definitely shouldn’t fight to sustain our greed.