The Symbiotic Relationship Between Gobies And Pistol Shrimp
However the shrimp have really poor eye-sight and being almost blind, cannot spot their predators until it's too late. The Goby fish (Gobies in. An example of mutualism involves goby fish and shrimp (see Figure below). The nearly blind shrimp and the fish spend most of their time. Details of the shrimp-goby mutualism differ a little bit depending on of the fish Cryptocentrus cryptocentrus (Gobiidae) and the pistol shrimp.
The shrimps belong to the pistol shrimps of the genus Alpheus, shrimps that often dig burrows. The gobies, in contrast, have excellent vision, and, furthermore, have their pelvic fins extended as a pedestal. In the relationship between the shrimp and the goby, the Alpheus shrimp digs a burrow, which is used as shelter by both the shrimp and the goby.
In turn, the goby spends its day outside the opening of the tunnel, resting on its extended pelvis fins, and keeping carefully watch over the immediate area, alerting the shrimp when danger comes to close, resulting in the shrimps retreat into the burrow. Goby with partner shrimp The goby-shrimp relationship is an example of what is called an obligate mutualism.
These gobies are never found without their shrimp partners, and, conversely, the partner shrimp are never found without their goby partners. As far as I know, coral reef areas and their immediate surroundings offer by far the most examples of such interspecies symbiotic relationships essential for both species survival.
The real cool thing about the shrimp-goby symbiosis is that the shrimp and the goby go one step further in their coevolution than most other species pairs. The goby is capable of communicating levels of danger to the shrimp. Thus, the shrimp sometimes respond to signals from the goby by working closer to the burrow opening, sometimes by working in the actual burrow opening, and sometimes by totally retreating into the burrow itself. This quite detailed interspecific communication is very rare in nature, at least when invertebrates such as shrimp are parts of the interaction.
Goby with partner shrimp The actual method of the communication between the pair is performed by contact of one of the very long antennas of the shrimp to the posterior dorsal fin of the goby. When the shrimp wants to get out of the burrow the shrimp first extends one of the antennae out of the opening, contacting the fin of the goby.
The shrimp did not show any optical orientation at all, but the gobies did. Gobies could differentiate potential partner shrimp by sight Karplus et al. If unsuitable partners were presented in experiments, the gobies stayed away. In reverse, the shrimp found their partners by smell.
There was interest from the beginning about what the burrow looked like, but all that was visible from outside was the entrance. The tubes were filled with sand before the experiment started.
After the shrimp excavated the tubes, the partnership could be viewed. This setup, however, appeared too artificial to me.
Yanagisawa even poured resin into burrow openings in the wild. The burrows went down as far as 1. The burrow often divided, and the tunnels extended into chamberlike structures.
Larger coral rubble pieces or skeleton parts of sand dollars were integrated into the burrow. My Observations These trials to find out more about the burrow system just fueled my interest to find out what was really going on inside.
The Symbiotic Relationship Between Gobies And Pistol Shrimp
Among marine aquarists, it was not even known that couples of shrimp and couples of gobies naturally live together. Most aquarists were happy to have one shrimp and one goby in their tank combined.
Where and how would they reproduce? Existing observation did not have an answer for this question. But how could I look inside the burrow? I noticed that the shrimp tended to build their burrows along the bottom glass of the tanks. Steady beating of the abdominal appendages pleopods kept the bottom glass free of sediment.
So I set up a gallon tank on a high rack, enabling me to sit below and to observe them through the bottom glass of the tank. The frame of the rack just held the tank around its circumference.
To reduce any potential negative impact from light below, I covered my observation chamber with a black curtain. I took videos or pictures with just a little light that I could switch on.
Both species were caught and imported in larger numbers together from Sri Lanka. Amalgamating the couples of fish and shrimp was not an easy task.
The blind shrimp and the macaroni goby - NAD-Lembeh Resort
If same sexes are in a small tank, it often ends in severe trouble—the shrimp are able to kill each other in an aquarium. Therefore I kept them as far apart as possible in separate tanks until I could identify the sexes of the shrimp female shrimp have a more broad abdomen and more broad pleopods.
I also kept the young gobies separated.
By changing the partners in one tank, I could easily find out if two specimens would go together, which is the indication for different sexes. In the next step, I brought both couples together in the observation tank.
I kept the interior of the tank simple: The shrimp started building the burrow immediately after I introduced them in a little cup and directed them into a gap I made under a piece of live rock.
Then the fish were added. It did not take longer than an hour, and the double couple was together. During the next days, the burrow grew.
The shrimp transported all excavated material and pushed it outside the burrow. They used their claws to push the sand like a little bulldozer. This astonishing skill can only be performed if the goby is out to guard their safety. When the tunnel system grew, the partner behaved differently under subterranean conditions. The narrow space in the burrow causes them to squeeze their partners against the burrow wall. The fish tend to wiggle through the burrows with force and no hesitation toward their crustacean partners.
Due to the action, parts of the burrow system would often collapse. A fish buried under sand stays there without panic the shrimp can smell it and waits until the shrimp digs it out and begins to repair the burrow. The main way into the burrow can be up to 2 feet long during the first days of excavation.
Soon after, side ways are constructed, which can be as short as 2 inches. They can be driven forward and later form an exit to the surface, or they are extended to form a subterranean chamber. Repeatedly, I could observe the shrimp molting in these chambers. This happens during the night every two to four weeks. The next morning, I would find exuviae close to them, and the female was carrying eggs on her abdominal legs if the shrimp are in good condition, molting and egglaying coincide.
The shrimp cut the exuviae into pieces and transported them out of the burrow as soon as their new test hardened. Hatching of the zoea larvae seems to happen overnight, which makes sense to avoid predators as long as possible.
The currents caused by the beating of the pleopods must pump the eggs out of the burrows, where they become a part of the plankton. The shrimp are omnivorous and collect large pieces of frozen fish positioned close to the entrance of the burrow.
They collect the food and transport it immediately into the burrow, where they feed on it. However, outside they can also be observed eating algae growing on rocks. The shrimp directly gnaw with their mouth pieces on rock where algae is growing. Even more fascinating was that I found parts of the algae Caulerpa racemosa inside the burrow system, though it grew more in another edge of the tank.
It took some time until I could observe that the shrimp cut these algae with their claws if they get access to it. However, that can only happen when fish and shrimp are on a coexcursion outside the burrow. In one instance, after cutting, the shrimp lost the algae due to the currents in the tank. But the unexpected happened: The goby immediately took action and grabbed the Caulerpa with its mouth. That moment, the shrimp lost antenna contact with the fish and quickly rushed backward to the entrance.
The goby transported the lost food to the entrance and spit it out into the entrance of the burrow where the shrimp was waiting. The fish was actively feeding the shrimp!