Monetaria annulus, commonly known as Gold-ringed cowry, usually attracts aquarium enthusiasts not so much with the shape of their shells, but rather with their very unusual coloring and pattern.
Gold-ringed cowry snails are gorgeous, easy to care for, and low-maintenance pets. Additionally, they can serve as exceptional cleaners for small reef aquariums, owing to their dietary preference for algae.
In this detailed guide, I have gathered all information about Monetaria annulus based on existing studies, research, and experience of aquarists.
Interesting fact: Cowries are in high demand by shell collectors. Many tourists buy the crafts as souvenirs, thereby providing a source of livelihood for the people in coastal fishing communities
Quick Notes about Gold-Ringed Cowry Snail
|Cowrie Snail, Ring cowrie, or Ring top cowrie
|Monetaria annulus (previously Cypraea annulus)
|Tank size (minimum)
|10 gallons (~40 liters)
|0.8 – 1 inch (2 – 2.5 cm)
|80 – 86°F (27 – 30°C)
|SG = 1.021 – 1.025
|8.1 – 8.5
|8 – 12
|Less than 20 ppm
|up to 5 years
|Purplish blue or white
Taxonomy of Gold-Ringed Cowry Snail
In 1758, this species was described by Swedish biologist and physician Carl Linnaeus (1707-1778) as Cypraea annulus.
Note: Carl Linnaeus is often called the Father of Taxonomy. His system for naming and classifying organisms is still widely used today. His ideas have also influenced generations of biologists.
In the early 2000s, a revision occurred, and this species was reclassified into Monetaria annulus.
Monetaria annulus belongs to the following taxonomy:
- Kingdom: Animalia
- Phylum: Mollusca
- Class: Gastropoda
- Order: Littorinimorpha
- Family: Cypraeidae
- Genus: Monetaria
- Species: Monetaria annulus
Currently, it is presumed that this species may have several subspecies, but discussions are ongoing as some believe that certain subspecies could actually be distinct species.
- Monetaria annulus var. alboguttata
- Monetaria annulus var. meli
- Monetaria annulus var. camelorum
- Monetaria annulus var. noumeensis
- Monetaria annulus var. sublitorea
- Monetaria annulus var. obvelata
Etymology of Monetaria Annulus
The genus name “Monetaria” is derived from the Latin word “Moneta”, which means “Money or coin.” This is a reference to the historical use of cowry shells as a form of currency.
Interesting fact: Cowry snails were the earliest form of international currency in human history. Initially, people started using them in China during the Neolithic era (around 3000 BC).
The species name “Annulus” is also derived from Latin and means “Ring or circle.” It refers to the characteristic ring or circle patterns often present on the shells of species within the Monetaria genus.
Distribution of Gold-Ringed Cowry Snail
The northern limit is observed in Boso, Japan, and the southern limit is in Algoa Bay, South Africa.
Habitat of Gold-Ringed Cowry Snail
Gold-ringed cowries are usually found in the middle and lower intertidal areas in shallow water, tide pools, under stones, or among seagrasses. They inhabit rocky, muddy, and sandy shores at depths of 6.5 ft (2 meters).
Description of Gold-Ringed Cowry Snail
Gold-ringed cowries are relatively small in size. According to Wikipedia, they can grow up to 2 inches (5 cm), but that’s not accurate. Research shows that the average size of adult snails ranges from 0.8 – 1 inch (2 – 2.5 cm). Occasionally, there are individuals that are 1.2 inches (3 cm), but they are exceptions rather than the norm.
Distinguishing characteristics of Monetaria annulus:
Shell. The shell is smooth and slippery with small spots.
Shape. This species has a high diversity of shell morphology due to genetic, geographic, ecological, and sexual dimorphism variations. For example, in open area waters, the shape of the shells is usually more globular than the shells found in semi-open areas.
Shell color. It is purplish blue or white.
Color pattern (Blotch). Blotch is one of the unique characteristics of these snails. The color is generally golden yellow and it has a ring-shaped form so this species is generally known as “gold ring cowries”.
Teeth and aperture. In Monetaria annulus has a protrusion of the collumellar and small labial teeth. The aperture is pretty narrow.
According to the study, when these snails are young, their soft bodies get bigger, especially when the shell is delicate and coiled. After that, they add a hard layer to the shell surface, forming a callus. Similar to some other snails, cowries stop growing after they build this callus, meaning both the soft body and callus thickness won’t increase anymore.
|Gold-ringed cowries have an amazing ability to elongate their mantle, allowing them to completely cover their shells. Considering that many of them have unique textures, it results in truly remarkable variations.
Difference Between Monetaria annulus and Monetaria Moneta
When choosing these snails at the aquarium store for your tank, you may come across nearly identical species. For instance, Monetaria moneta is almost a twin to Monetaria annulus. Nevertheless, there are ways to distinguish them.
|generally longer and the grooves between them more defined
|generally shorter and finer
|distinctive gold ring
Lifespan of Gold-Ringed Cowry Snail
Unfortunately, knowledge of these snails is scanty. There is no official data on the maximum lifespan for Monetaria annulus in the wild. In aquarium settings, it is generally around 3 to 5 years.
Typical Behavior of Gold-Ringed Cowry Snail
Gold-ringed cowries are non-aggressive and docile by nature. They are only focused on their grazing and exploration activities.
They are primarily active during the night and often spend the daytime hiding and resting.
Gold-ringed cowries usually do not exhibit burrowing behavior. Instead, these snails are known to climb on surfaces and explore their surroundings.
Although in the wild, these snails are found in high densities, but that does not mean that they are social. They simply do not care much about other snails unless they decide to mate.
Therefore, like most snail species, they are solitary in their behavior and do not actively seek out the company of other snails.
- Social: No
- Active: At night
- Peaceful: Yes
- Burrowers: No
Diet of Gold-Ringed Cowry Snail
These snails are primarily herbivorous. In the wild, they mostly eat algae, detritus, diatoms, cyanobacteria, and slime that builds upon rocks. All in all, they are great scavengers.
In aquariums, Gold-ringed cowries will be our vanguard force against algae and detritus. This clean-up crew will take care of this for you in the absolute majority of cases.
Depending on your tank setup, once they eat all (most) algae, they may need to be fed supplementally for long-term maintenance.
If there are no algae in your tank, give them algae tablets or at least any type of fish, shrimp, or crab food.
Are Gold-Ringed Cowry Snail Snails Reef Safe?
Yes, Gold-ringed cowries are completely reef safe. Their small size will not allow them to bulldoze through the corals. So, they won’t damage anything in a reef tank
But the most important thing is that there is no need to worry that they may try to snack on your corals. Just do not starve them.
Caring and Keeping Gold-Ringed Cowry Snail
Gold-ringed cowry snails are low-maintenance and easy to care for. They do not require large tanks and are pretty forgiving when it comes to water conditions.
Because of their small size, there are no minimum requirements. Basically, even nano marine tanks (10 gallons or 40 liters) will be good enough for a few Gold-ringed cowry snails.
Important: If you are a beginner, you should understand that there are several potential problems with small tanks:
- It can be difficult to keep your water parameters stable.
- It can be hard for the snails to find enough food and you can have feeding problems.
Temperature: Gold-ringed cowries snails prefer warm water in a range of 80 – 86°F (27 – 30°C). However, they can easily tolerate temperatures down to 72°F (22°C).
Temperature has a direct effect on their calcification process. According to the study, calcification was accelerated by increasing temperature in the range between 70°F (21°C) and 91°F (33°C), and drastically slowed down at 93°F (34°C).
pH: Maintain optimal pH values of 8.1–8.5 for the snails to thrive in your saltwater aquarium. In the same research, it was also mentioned that the snails were found in waters with pH range between 7.03 – 7.68.
Hardness: Keep water hardness values between 8–12 dKH.
SG: specific gravity is between 1.021 and 1.025.
Calcium and Magnesium: Keeping calcium concentration in the range of 400 to 450 ppm and magnesium between 1250 and 1350 are optimal.
Since Gold-ringed cowries are nocturnal animals, they do not really need much light.
In their natural habitats, they tend to live in areas that are protected from sunlight such as coral reefs, rockpools, seagrass leaves, etc.
If you keep corals and fish in the tank, the lighting should be adapted to their needs.
There are no special requirements either.
As long as you have got a filter that works great with the size of the tank you have got, you will be fine.
The best substrate for Gold-ringed cowries is smooth gravel and rocks because it is better for algae growth.
The aim of incorporating decors in an aquarium is to replicate the natural habitat and provide enough hiding places for the snails.
In addition, they provide a lot of surface area for algae and diatom growth. Thus, any decor will be a good choice for a marine tank with Gold-ringed cowries.
Breeding Gold-Ringed Cowry Snail
Unfortunately, breeding cowries, in a home aquarium can be a complex task due to the specific environmental conditions required for successful reproduction. Factors such as water quality, temperature, and the availability of suitable food sources are crucial.
Currently, the pet industry depends on wild-caught species.
Some facts about mating and breeding Gold-ringed cowries snails:
- The life cycle of intertidal cowries consists of the veliger, juvenile, callus-building, and adult stages.
- The shell length of females (22-26 mm) is larger than those of males (17-24 mm).
- Monetaria annulus has 2 reproductive seasons, in spring and from late summer to winter.
- Veliger larvae hatch from eggs laid by females on the substrate.
- Free-swimming veliger larvae spend their planktonic life in the pelagic zone.
- The larvae settle to the bottom, experiencing the first metamorphosis.
- Cowries develop a juvenile shell on their veliconch after settlement.
- The growth of the juvenile shell continues until the shell aperture narrows, producing teeth.
- Cowries thicken the ‘callus’ by coating the outer surface of juvenile shells with calcareous materials in the pre-adult stage.
With their interesting appearance, Gold-ringed cowry snails will definitely be an attractive addition to any marine aquarium.
These snails are scavengers and voracious algae eaters.
As for keeping them in the tank, this is a simple species to care for. Even beginners will be able to keep them since they are quite undemanding.
- Villamor, Shiela, and Tomoko Yamamoto. “Population characteristics of Monetaria annulus (Linnaeus, 1758)(Gastropoda: Cypraeidae) from temperate to tropical areas.” Aquaculture Science63, no. 3 (2015): 273-282.
- LATUPEIRISSA, LOUVENSKA N., and FREDY LEIWAKABESSY. “Species density and shell morphology of gold ring cowry (Monetaria annulus, Linnaeus, 1758)(Mollusca: Gastropoda: Cypraeidae) in the coastal waters of Ambon Island, Indonesia.” Biodiversitas Journal of Biological Diversity21, no. 4 (2020).
- Irie, T., and B. Adams. “Sexual dimorphism in soft body weight in adult Monetaria annulus (Family Cypraeidae).” Veliger49, no. 3 (2007): 209-211.
- Irie, Takahiro, and Naoko Morimoto. “Intraspecific variations in shell calcification across thermal window and within constant temperatures: experimental study on an intertidal gastropod Monetaria annulus.” Journal of Experimental Marine Biology and Ecology483 (2016): 130-138.