After a long wait, we’re very happy to bring you another episode of our “Take a Minute to Relax” series. The guest star in it is both flamboyant as well as interesting and goes by the scientific name Amblyeleotris randalli. In the common tongue, there are numerous names for this beautiful creature. Gold-barred Shrimp Goby, Gudgeon, Orangestripe Prawn Goby, Orangestripe Watchman Goby, Randall’s Shrimp Goby, Sailfin Shrimp Goby, just to name a few.
Amblyeleotris randalli is a relatively small fish that can grow to about 12cm/4,7”, and can be found in the Western Pacific region. It is part of the Family Gobiidae (Gobies), which is the largest family of marine fishes on the planet, containing nearly 2000 species, possibly even more. One would think that in a family of that size, it’s near impossible to stand out. However, about 120 species of this family have developed a remarkable evolutionary trait, that did just that!
These select few started a mutualistic symbiosis with a completely different creature, namely shrimps of the family Alpheidae. These shrimps are characterized by having asymmetrical claws, the larger of which is typically capable of producing a loud snapping sound, which creates a cavitation bubble that is loud enough to stun their prey. It, therefore, comes as no surprise that these creatures are also commonly known as snapping shrimp, or pistol shrimp. The Alpheid shrimps are incredible diggers, and are constantly creating, and maintaining burrows in the seabed which provides them with a relatively safe place to live.
However, due to their very poor vision, the shrimps are extremely vulnerable to predators every time they dump sand, and/or gravel, outside of their burrow. And this is where the shrimp/partner gobies come in. Amblyeleotris randalli, as well as the other shrimp/partner gobies, have excellent eyesight, and like a watchmen/guardian, it maintains constantly vigilant against potential predators, while the shrimp continues the digging and maintenance activities. This way, the shrimp gets security, and the goby gets a safe home with cleaners. What a clever way for 2 small creatures to increase their chances of survival!
A very interesting aspect of this particular symbiosis is the communication between goby and shrimp. So far it’s been established that when a predatory fish approaches the burrow entrance fast, the goby escapes into the burrow. This escape reflex is very similar to that of other fishes. However, when a predatory fish approaches the burrow at a moderate distance or speed, the goby flicks its tail, and/or dorsal fin, in quick bursts, so that the shrimp, who’s in touch with the body of the goby via its antennae, notices the message and stays below ground. This type of messaging is signalling a threat level below the „full escape“, and is information specifically communicated to the shrimps!
Since behavioural science of marine life is still in its infancy, hopefully, scientists will bring us more interesting facts about their inter-species communication in the future. Perhaps even more remarkable, is that this symbiotic relationship between shrimp and goby lasts a lifetime. They start bonding as juveniles and remain together as adults, spending their days foraging together and sharing a burrow. It is still unclear why these two species have developed such a high level of co-dependency, but the symbiosis is working well for both creatures. Gobies eat micro-fauna, and sometimes small fish that they find near the bottom.
The shrimps, on the other hand, feed on what they find during their burrowing and therefore do not compete with the gobies for food. While shrimp reproduction isn’t all that remarkable, the reproduction of gobies on the other hand has some peculiar aspects. During the mating season, the male and female gobies start a wild circular dance in an extended side corridor of the burrow. They touch and stimulate each other from head to tail, which causes sand and gravel to fall from the ceiling and walls. The shrimp’s digging/cleaning actions play an important role in ensuring that the mating ritual can continue, as gobies don’t have the ability to transport the sand themselves.
Hence, the preparation of the gobies breeding chamber, as well as the constant maintenance during the actual mating, and by extension, the successful procreation of the particular goby species, is only possible with the shrimp’s assistance! If by now you’re wondering how gobies and shrimps find each other in the first place, know that science hasn’t found a definitive answer to that question yet. Marine biologists have conducted numerous experiments to determine who finds who, and how, but currently, this question remains one of nature’s enduring mysteries …