Ornamental shrimp make great additions to many saltwater aquaria. In addition to being attractive (most are), those shrimp that are symbiotic make for fascinating displays. Many an aquarist has designed a nano tank around such a shrimp, although they also make fantastic additions to an invertebrate or reef tank. Symbiotic shrimp are amongst the most interesting species in the hobby—some aquarists even prefer them to the popular clownfish-anemone relationship (no offence, Nemo).
The reef is a harsh environment. We know it looks peaceful and serene while snorkeling or diving, but the reality is that it’s tough to make it on a reef with so many organisms competing for resources. This is perhaps why we see so many relationships on the reef between organisms that we might not expect to benefit from one another. These relationships are known as symbiotic relationships, and they come in three main categories:
The relationship is mutualistic when both organisms involved benefit from the relationship, and it is commensal when only one organism benefits while the other neither benefits nor suffers. The symbiotic shrimp we are discussing here fall into these two categories—mutualistic and commensal. Let’s take a look at a few of the most popular species.
Shrimp and Shrimp Gobies
Pistol shrimp, from the genera Alpheus and Synalpheus, pair up with gobies from the genera Amblyeleotris and Stonogobiops in a relationship that may benefit both and is definitely interesting to watch. Pistol shrimp, sometimes called alpheid shrimp, are readily identifiable by way of their asymmetrical claws. The shrimp derives its common name—pistol shrimp—from the larger claw, which is capable of making a loud snapping sound. In addition to producing this noise (which will startle you the first time you hear it), these shrimp are often beautifully colored, although you won’t see them much as they spend most of their day in the burrow they dig, and this is where the symbiosis comes into play.
Shrimp gobies will naturally pair up with pistol shrimp in the marine aquarium. The two will share a burrow, and when the nearly blind pistol shrimp does emerge from the burrow, it will stay in constant contact with the goby, which acts as the shrimps eyes. One of the more popular shrimp gobies is the Yasha Hasa Shrimp Goby (Stonogobiops yashia), which can be paired with a Randall’s Pistol Shrimp (Alpheus randalli). Other interesting and attractive shrimp gobies include the Yellow Rose Goby (Stonogobiops nematodes), the Randall’s Shrimp Goby (Amblyeleotris randalli), and the Orange Spot Shrimp Goby (Amblyeleotris guttata). Popular pistol shrimp species include the above mentioned Randall’s Pistol Shrimp and the Tiger Pistol Shrimp (Alpheus bellulus).
Sexy Shrimp and Coral
While the pistol shrimp-shrimp goby relationship may be said to be mutualistic, the relationship between a very small (but very sexy) shrimp is most certainly commensal. The Sexy Shrimp (Thor amboinensis) lives within the protection of both corals and anemones. Benefitting from the protection provided by the anemone’s tentacles or from the tentacles of large-polyped stony corals, the Sexy Shrimp can survive in an environment where it would otherwise be an easy snack for countless reef inhabitants. Seeing one of these Sexy Shrimp perched in its host and doing its namesake “sexy” dance is a sight to behold in the aquarium. This commensal shrimp does not appear to give any benefit to the host, but it also does not harm the host in any significant way. In terms of hosts, many sexy shrimp actually seem to prefer hosting in coral from the genus Euphyillia. Anchor Coral (Euphyllia ancora), for example, is a favorite.
While the sexy shrimp does not provide any real benefit to its host, another variety of shrimp - so-called cleaner shrimp - provide very real benefit to their tankmates. In addition to cleaning parasites and other small organisms from your fish, many cleaner shrimp are also highly attractive. The Scarlet Cleaner Shrimp (Lysmata amboinensis), for example, will set-up a cleaning station and advertise its services to your fish. Imagine a cleaner shrimp hitching a ride on one of your fish in order to carefully clean the fish of parasites and other small organisms. Another cleaner shrimp commonly known as the Peppermint Shrimp (Lysmata wurdemanni) tends to do less cleaning in the aquarium than the Scarlet Cleaner Shrimp, but what the Peppermint Shrimp lacks in fish-cleaning gumption, it more than makes up for in feeding on detritus at night. In addition, Peppermint shrimp are know to eat a small pest anemone called Aiptaisia, and many aquarist value this non-chemical solution to an Aiptaisia outbreak.
As you can see, there are many interesting shrimp from which the marine aquarist can choose. Some of these shrimp form symbiotic relationships with other organisms in your aquarium. These relationships are amongst the most interesting relationships to observe in the hobby. There are few good reasons not to have shrimp in your invertebrate or reef tank, although, as always, you should thoroughly do your homework, as some shrimp are decidedly not reef safe.