Symbiotic Relationships in the Natural Environment: The Goby and Pistol shrimp… Nature’s guide dog
The symbiosis between gobies and pistol shrimp is one of the many that can occur in our marine aquariums. In the goby and pistol shrimp symbiosis, both. An expert marine fishkeeper examines the fascinating symbiotic relationship between pistol shrimps and the gobies they partner with in the reef aquarium. One of the more curious relationships that most divers would have come The Pistol Shrimp or Snapping Shrimps of the Alpheus shrimp.
The nearly blind shrimp can then retreat into the burrow to be spared from predation. These animals participate with each other on a highly elaborate and evolved level—and it becomes more impressive when you think about how they are in no way related. This is an amazing partnership, but what goes on inside of the burrow that they both inhabit? Until recently, we have only been able to observe their behavior outside of their elaborate burrows.
I have been able to make some new observations with an interesting tank setup. First I will tell you the history of studying this particular symbiosis, then I will let you know how you can set up a tank specifically for viewing this symbiosis, and then I will relate my new findings. A Scientific History Luther, when he was a junior scientist, managed to catch a goby and pistol shrimp pair and put them in a small fish aquarium after they had been discovered during a expedition of the Red Sea.
Indeed it took a lot of time until these peculiar couples were back in scientific focus. It was again in the Red Sea, and the same species of fish and shrimp that came to the awareness of biologist Ilan Karplus in the s and s. He and his associates studied how these animals communicate, their territorial behavior, the dynamics of building the burrows and the distribution of the different species. Observing them in nature by diving was difficult at best; scientists could lay down in front of the burrow entrances until their air ran out.
It took a long time to observe them because any disturbance caused them to stay inside the burrow for hours. Everyone who has tried to take pictures of them in nature is aware of this. Today we know that the symbiosis between gobies and pistol shrimp is an evolutionary model of success. The majority of these are found in the Indo-Pacific and adjacent regions. There are goby generalists that live together with different shrimp, but there are also specialists living with just one species Karplus et al.
Species differ concerning the distribution of their partners, their age and sort of substrate different gobies prefer finer or more coarse sediment.
Pistol Shrimp and Gobbies: Perfect Partners
Shrimp leave the burrows only during daylight in company with the gobies. Shrimp or gobies never lived alone in a burrow, and the minimum count was a single shrimp and a single goby. More often, a couple of gobies and a couple of shrimp were found in one burrow.
To observe the association in aquaria was another approach to find out more. The partners had to find each other in a Y-shaped testing channel, either by optical or olfactory abilities. 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.
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. 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.
Some species of goby also appear to feed their shrimps, spitting food into the burrow, and even without such deliberate actions it's possible that the shrimps may feed on fragments of food that the gobies drop. Meet the Gun-Slinging Shrimps While many species of pistol shrimps are found in a wide variety of habitats, only a few are commonly kept in aquariums. These are species of the genus Alpheus. It has a white body with complex brown or reddish-brown markings.
Some individuals have purple markings on the legs. Both associate well with many different goby species.
The Symbiotic Relationship Between Gobies And Pistol Shrimp
Another very attractive, but less often imported, species is the golden pistol shrimp often referred to as A. One other Alpheus pistol shrimp deserves a mention, A. There are other Alpheus species, and other pistol shrimps, that find their way into aquarium stores, but they are often of unknown species.
And Their Goby Guests Several genera of gobies associate with pistol shrimps. They can be and usually are kept without shrimps, and most are good aquarium fishes in their own right. They are generally hardy and easy to feed, but many even the robust-looking Cryptocentrus gobies can be quite shy, and they are prone to jumping from open aquariums or even through gaps in aquarium covers.
They often seem to be both bolder and less prone to jumping when kept with shrimps—perhaps having an expertly constructed bolt-hole close at hand makes them more confident.
To overcome this, make sure that some food drifts past their hiding place e. The most common aquarium imports are species of Amblyeleotris, Cryptocentrus, and Stonogobiops, although other species are sometimes offered for sale. There are 38 species of Amblyeleotris, which in the wild associate with a variety of Alpheus shrimps.
Many of them look quite similar: There are some more distinctive species in this genus, notably Randall's shrimp goby A. Also distinctive, if seldom seen in aquariums, is the giant shrimp goby A. Four species are seen relatively frequently in the aquarium trade: Stonogobiops species usually associate with Alpheus shrimps, particularly A. Cryptocentrus species have a more robust look than most other shrimp gobies, with frog-like heads and big mouths.
They tend to be more aggressive towards related species, and in the case of the larger species even towards other tankmates, than other shrimp gobies. Not many of the 34 species find their way into the aquarium trade with any frequency. The most popular species is the yellow watchman goby C.
It grows to around 6 inches 15 cm and is grayish but with bright pink spots and blotches as well as smaller neon-blue spots. Numerous other Cryptocentrus species are occasionally offered for sale, and while relatively little is known about their care, they can probably be expected to behave in a similar way to their more familiar congeners.
In the wild, Cryptocentrus associate with a variety of Alpheus shrimps. Creating a Home for Gobies and Shrimps Shrimp Considerations When keeping pistol shrimps and gobies, the main area of concern is what the shrimp will do to the aquarium.
Pistol shrimps have one preoccupation: This in itself makes them very interesting and entertaining aquarium inhabitants, even without gobies, but it does need to be taken into consideration when setting up the tank. The first requirement is to make sure that any rocks are securely positioned on the base of the tank—neither sitting on top of the sand or gravel substrate nor leaning on it. Pistol shrimps can easily undermine rocks when digging, leading to potentially tank-breaking landslides.
A deeper bed is best, but about 3 inches 8 cm will do. Corals sitting on the sand may be buried, or if small enough frags, for example carried off and used as building material. In my large reef tank a small pistol shrimp occupies an area of about 15 x 15 inches 38 x 38 cmwithin which only large rocks are safe.
The shrimp will work around them. Apart from their desire for plentiful supplies of building materials, pistol shrimps are generally less demanding in the aquarium than many other crustaceans. Like other types of shrimp, they should have a slow, careful acclimation when first added to the tank, but once established they seem to be rather hardier than, for example, cleaner or peppermint shrimps. They seem to be more tolerant of salinity and temperature swings. Feeding pistol shrimps is easy.
They will eat frozen crustaceans Artemia, krill, mysid shrimp, and copepods as well as hunt their own food. A certain amount of care is required when it comes to choosing crustacean tankmates for pistol shrimps. Large pistol shrimps although not the species generally kept with gobies are fairly formidable mini-predators and can easily capture and kill smaller aquarium shrimps such as Lysmata, Thor, and Rhynchocinetes species.
Smaller ones, however, despite their snapping claws, are vulnerable to predation when molting, which, like other shrimps, they do regularly in order to grow.