The Symbiotic Relationship Between Gobies And Pistol Shrimp
The Randall's pistol shrimp has a symbiotic relationship, known as mutualism, with a fish called the Randall's prawn goby (Amblyeleotris. Coral Reefs, thousand of species, thousand of associations: but the relationship between little gobies and their shrimp partners is one of the most famous and. Special relationships: Keeping pistol shrimps and gobies . Randall's goby (A. randalli) from the Western Pacific is one pretty fish, reaching no.
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.
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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.
Pistol Shrimps and Gobies: Perfect Partners (Full Article)
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.
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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! I tested this observation and pulled algae off the rocks. When the fish was in the entrance of the burrow, I threw a 1. The goby directly approached it while it was still floating in the water column, collected it and brought it to the burrow.
That collecting behavior could be induced up to five times repeatedly. The shrimp handled the algae inside the burrow in the meantime. I could never observe that the shrimp were keeping algae in certain parts of the burrow. There was not a special storage chamber for algae pieces. Instead the algae pieces were pushed around, and the shrimp fed on them here and there. After some days, the algae disappeared completely. Breeding in the Burrow While the reproduction of the shrimp is not spectacular, that of the gobies bears some peculiar aspects.
Close to mating, the male and female gobies start a wild circular dance in an extended side corridor of the burrow. They stimulate each other head to tail, which causes sand and gravel to fall from the ceiling.
The gobies can successfully mate only when the shrimp are healthy and have hard tests. The female does not go back to the breeding chamber—the male fish is the only one to care for the eggs. Usually, he moves the approximately 2, eggs which can easily be done, as the eggs are attached to each other and form a bundle by moving his pectoral fins backward and forward. He swims around the eggs once in a while, which supplies oxygen to the eggs.
Oxygen is low in chambers deep in the sand; only intensive care will keep them oxygenated. The male goby protects the eggs against a potential predator in the burrow: In fact, the shrimp couple never gets access to the fish eggs.
The male goby is busy guarding the eggs during this period and rarely leaves the burrow. If he does leave, he closes the breeding chamber with sand.
He pushes sand into the entrance of it with his head or tail. When he comes back, he just wiggles through the pile of sand to come back to the eggs. After seven to 10 days depending on temperature or perhaps oxygen supply the larvae are ready to hatch. Hatching always happened at night with my fish, and by morning the larvae had all left the burrow, probably guided by the light.
Giving and taking is incredibly developed in this symbiosis and likely evolved under the influences of the harsh environment with limited access to shelter and food. Reproductive success depends on the activity of the partners. To protect their offspring, the gobies keep the shrimp away. Keep in mind that different species of goby associated with another shrimp species will exhibit some different behaviors than those that I observed. The capacities of both partners depend, for example, on body size.
A tiny shrimp such as the reddish-white banded Alpheus randalli which can be found together with smaller gobies such as Stonogobiops species simply cannot handle the excavation work necessary for a larger fish, such as Cryptocentrus species. Natural enemies like Lizardfish, Jackfish, Sandperches and some other predators like snake eels have been observed sometimes successfully hunting Shrimp-Gobies. It's a chicken-and-egg debate if is the goby first to find the shrimp, or the shrimp that finds the goby: Apparently gobies find their partners mainly using their visual ability, while chemical signals seem to have a prevalent role from the shrimp's point of view: This relationship can begin shortly after the goby settles from planktonic life, when the little fish is almost 1 cm long.
When the sexual maturity is reached, normally a pair male-female of gobies shares the same burrow together with a pair of shrimps. A Black-Rayed Shrimp-goby Stonogobiops nematodes hovering out of his burrow where a shrimp Alpheus randalli keeps removing sand. Species belonging to the genus Stonogobiops have a swim bladder, feature not very common in the Gobiidae family. Not every Shrimp-Goby shows nice colors: On the contrary, his fellow shrimp Alpheus sp.
In this case a pair of Alpheus ochrostriatus share the burrow with Broad-Banded Shrimp-Goby Amblyeleotris periophthalma. It's almost impossible to distinguish the sex of the shrimps without bringing them out of the water, anyway sometimes even male-male or female-female pairs have been observed. When the pair it's formed, the process of building the burrow starts and, depending on the substrate and on the species of shrimp, could be short and branching, or long and deep, as it has been observed sometimes in some aquariums where the shrimp decided to build his house nearby to the glass.
The activity of the pair during the day is quite intense: The goby, aside from his watchman duties, is busy in catching his food mainly zooplankton. Most gobies just lay down on the sand waiting, while some others hover on the top of the hole. The pair activity normally is reduced in the late afternoon, and in some cases during the night the shrimp closes the burrow entrance as a further protection against night predators.
Watchman Goby More than different goby species belonging to almost 20 genera are officially already described, but probably many other are still waiting to be discovered, especially in the Coral Triangle area Indonesia, Malaysia, Philippines an Papua New Guinea. The symbiosis has been observed with up to 30 different species of pistol-shrimps, mainly of the genus Alpheus. Even Cryptocentrus is a successful genus and it's distinguishable for the bigger head and some other anatomical features.
Ctenogobiops and Vanderhorstia are quite diffused all around tropical Indo-Pacific waters, but few species have been official described until now. One genus particularly loved by aquarists, Stonogobiops, includes few species all with swim bladder that allows them to hover motionless few centimeters on the top of the burrow entrance. Shrimpgobies in the wild feed on zooplankton mainly. Quite often a couple of gobies inhabits the same burrow, where the female lays the eggs.
They are territorial fish even if the territory is not very large and in the same area it's possible to find several couples. They are not very good swimmer of course, but can be very fast. House-maid Shrimp All the shrimps living in association with a goby belong to the Alpheidae family genera Alpheus or Synalpheus.
They are even called "Snapping Shrimps" or "Pistol Shrimps" for their ability to produce a loud snapping sound using their larger claw. Even if they are so small, they are one of the major sources of underwater noise.