Ramshorn snail
Encyclopedia
The term ramshorn snail is used in two different ways. In the aquarium
trade it is used to describe various kinds of freshwater snail
s whose shells are planispiral, meaning that the shell is a flat coil. Such shells resemble a coil of rope, or (as the name suggests) a ram's horn. In a more general natural history
context, the term "ramshorn snails" is used more precisely to mean those aquatic
pulmonate gastropod mollusks in the family Planorbidae
that have planispiral coiled shells.
This article is about ramshorn snails in the aquarium trade. For more information on the Planorbidae, see the article Planorbidae
.
Ramshorn snails have been bred for the aquarium trade and various color forms have been selected. Most of the aquarium ramshorn snails are species in the family Planorbidae
, but one kind is from a totally different family, the Ampullariidae
.
Ramshorn snails can sometimes become a nuisance in an aquarium, because some of them breed so profusely.
, and they include the species Planorbarius corneus
. There are two different coloured skin forms: black and red; the latter lack the dark skin pigment melanin
and consequently have a bright reddish skin, which is the colour of their blood. Interestingly their blood
contains red hemoglobin
, unlike other snails' blood
, which contains greenish hemocyanin
.
These ramshorn snails breathe air. Although most of them are extremely small, some may reach a size of two and a half centimeters (one inch). The shells range from translucent through various shades of brown to a dark, nearly black color. The dark color appears to originate from dietary materials not generally available in the home aquarium, although many varieties from ponds are this dark shade.
Snails of this family are spiralled sinistrally, with the opening hole slanted downward toward the right. Large folds of skin may protrude out of the more open left side. Like all air-breathing water snails, the animal has no operculum
, and has only one pair of tentacle
s with the eye spots at the base of the tentacles.
They lay eggs in globules, which tend to be brownish in color. The globules contain about a dozen or so eggs, though it can vary. The globules are translucent, so it is possible to visually see the new snails develop in size. The newborn snails are clearish white.
, uneaten fish food, and dead fish
. Some varieties do particularly enjoy eating the leaves of stem plants such as cabomba
and anacharis.
Some aquarium species will eat ramshorn snails. More voracious eaters include loach
es (such as the clown loach
or any other member of the genus botia
), betta
s, crayfish
, and most gourami
s—though many other fish will also consume snail meat. The larger apple snail will also prey upon ramshorn snails.
Good fish roommates for snails include, but are not limited to, danios, guppies, White Cloud Mountain Minnows
, neon tetra
s, and cory catfish
. All of these are non-aggressive fish that cohabitate easily with snails.
One should also be aware that red ramshorn snails are able to carry various parasitic flukes, which can be transmitted to fish, or humans. Most of these flukes require intermediate host
s, so that leaving the snails by themselves for a month or so will eliminate the disease.
If the population is kept to a manageable size, ramshorn snails can be good tank cleaners. They eat algae and dead or dying plants generally, so they can be useful. However, if they breed too prolifically they can become a nuisance. In warm climates (such as those in mainland Australia or the southern United states) they much prefer ponds, especially outdoor ponds. Algae, dead leaves that sink to the bottom, general grime and dead animals can be a problem as they foul the water. Ramshorn snails eat all of these things. They do breed more prolifically in ponds because there is more food but they aren't as noticeable in a pond as they are in a tank.
bundles hidden in newly acquired plant
s. Although their red color may make them somewhat interesting aquarium subjects, their hermaphroditic
ability to breed prolifically from any two specimens can make them troublesome.
Common practices include treating plants to prevent introduction, various manual methods of control, introducing the snail-eating animals listed earlier, and poisoning the snails.
Soaking the plants in various chemicals may kill off the snails and their eggs. A 10 minute bath in a solution of 20 parts water to 1 part chlorine bleach
has been suggested for hardier plants, followed by soaking in water containing a dechlorinating agent. A more gentle treatment calls for 5-10 tablespoons of alum
to 1 gallon of water for 2–3 days. A safer alternative may be placing the plants in a quarantine
tank, and adding snail poisons to that tank rather than the main show tank.
Manual methods include baiting the snails with lettuce (run it under hot water first and leave overnight), cucumber
slices, or food pellets. These may be left out in the open, and removed with their snails, or kept in some container, such as a film canister weighed down with a pebble, and containing holes drilled in it. Crushing the snails by hand as they appear can also effectively limit their population; most ramshorn shells are fragile enough that this is quite easily done.
Snail poisons are generally considered to be a last resort, as most of them are copper
-based and are potentially toxic to plants and fish and particularly dangerous to other invertebrates. Even new safer chemicals that do not harm the other aquarium inhabitants may cause damage if large numbers of dead snails are allowed to decompose. For this reason, it is best to reduce the snail population by other means as much as possible before resorting to poisons, and to do frequent water changes afterwards. Some also recommend adding ammonium
protection to the tank. Zeolite chips, and various liquid products such as amquel may help in this area.
, which is often sold at pet stores under the name "Columbian ramshorn" or "giant ramshorn" snail. This species is actually a kind of apple snail, albeit one with a planispiral shell. They are distinguished by having an operculum by which they can close themselves into their shell, two pairs of tentacles, separate genders, and a siphon on the left side.
Its shell is yellowish, with brown stripes running the length of the shell. These apple snails lay gelatinous masses of eggs on submerged portions of plants. They can grow to up to four centimeters in size. They generally will not become a pest, although they can consume large amounts of plant matter.
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
trade it is used to describe various kinds of freshwater snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
s whose shells are planispiral, meaning that the shell is a flat coil. Such shells resemble a coil of rope, or (as the name suggests) a ram's horn. In a more general natural history
Natural history
Natural history is the scientific research of plants or animals, leaning more towards observational rather than experimental methods of study, and encompasses more research published in magazines than in academic journals. Grouped among the natural sciences, natural history is the systematic study...
context, the term "ramshorn snails" is used more precisely to mean those aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
pulmonate gastropod mollusks in the family Planorbidae
Planorbidae
Planorbidae, common name the ramshorn snails or ram's horn snails, is a family of air-breathing freshwater snails, aquatic pulmonate gastropod mollusks....
that have planispiral coiled shells.
This article is about ramshorn snails in the aquarium trade. For more information on the Planorbidae, see the article Planorbidae
Planorbidae
Planorbidae, common name the ramshorn snails or ram's horn snails, is a family of air-breathing freshwater snails, aquatic pulmonate gastropod mollusks....
.
Ramshorn snails have been bred for the aquarium trade and various color forms have been selected. Most of the aquarium ramshorn snails are species in the family Planorbidae
Planorbidae
Planorbidae, common name the ramshorn snails or ram's horn snails, is a family of air-breathing freshwater snails, aquatic pulmonate gastropod mollusks....
, but one kind is from a totally different family, the Ampullariidae
Ampullariidae
Ampullariidae, common name the apple snails, is a family of large freshwater snails, aquatic gastropod mollusks with a gill and an operculum...
.
Ramshorn snails can sometimes become a nuisance in an aquarium, because some of them breed so profusely.
Physical description
Most of these snails are of the family PlanorbidaePlanorbidae
Planorbidae, common name the ramshorn snails or ram's horn snails, is a family of air-breathing freshwater snails, aquatic pulmonate gastropod mollusks....
, and they include the species Planorbarius corneus
Planorbarius corneus
Planorbarius corneus, common name the great ramshorn, is a relatively large species of air-breathing freshwater snail, an aquatic pulmonate gastropod mollusk in the family Planorbidae, the ram's horn snails, or planorbids, which all have sinistral or left-coiling shells.The shell of this species...
. There are two different coloured skin forms: black and red; the latter lack the dark skin pigment melanin
Melanin
Melanin is a pigment that is ubiquitous in nature, being found in most organisms . In animals melanin pigments are derivatives of the amino acid tyrosine. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms...
and consequently have a bright reddish skin, which is the colour of their blood. Interestingly their blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
contains red hemoglobin
Hemoglobin
Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...
, unlike other snails' blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
, which contains greenish hemocyanin
Hemocyanin
Hemocyanins are respiratory proteins in the form of metalloproteins containing two copper atoms that reversibly bind a single oxygen molecule . Oxygenation causes a color change between the colorless Cu deoxygenated form and the blue Cu oxygenated form...
.
These ramshorn snails breathe air. Although most of them are extremely small, some may reach a size of two and a half centimeters (one inch). The shells range from translucent through various shades of brown to a dark, nearly black color. The dark color appears to originate from dietary materials not generally available in the home aquarium, although many varieties from ponds are this dark shade.
Snails of this family are spiralled sinistrally, with the opening hole slanted downward toward the right. Large folds of skin may protrude out of the more open left side. Like all air-breathing water snails, the animal has no operculum
Operculum (gastropod)
The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...
, and has only one pair of tentacle
Tentacle
A tentacle or bothrium is one of usually two or more elongated flexible organs present in animals, especially invertebrates. The term may also refer to the hairs of the leaves of some insectivorous plants. Usually, tentacles are used for feeding, feeling and grasping. Anatomically, they work like...
s with the eye spots at the base of the tentacles.
They lay eggs in globules, which tend to be brownish in color. The globules contain about a dozen or so eggs, though it can vary. The globules are translucent, so it is possible to visually see the new snails develop in size. The newborn snails are clearish white.
Interaction with environment
Ramshorn snails generally will eat only the most delicate plants, preferring algaeAlgae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
, uneaten fish food, and dead fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
. Some varieties do particularly enjoy eating the leaves of stem plants such as cabomba
Cabomba
Cabomba is an aquatic plant genus, one of two belonging to the family Cabombaceae. It has divided submerged leaves in the shape of a fan and is much favoured by aquarists as an ornamental and oxygenating plant for fishtanks...
and anacharis.
Some aquarium species will eat ramshorn snails. More voracious eaters include loach
Loach (fish)
Cobitidae is the family of the true loaches, which are Old World freshwater fish. They occur throughout Eurasia and in Morocco, and inhabit riverine ecosystems. Today, most "loaches" are placed in other families...
es (such as the clown loach
Clown loach
The clown loach, Chromobotia macracanthus, is a tropical freshwater fish belonging to the Cobitidae family. It is the sole member of the Chromobotia genus. It originates in inland waters in Indonesia on the islands of Sumatra and Borneo...
or any other member of the genus botia
Botia
Botia is a genus of freshwater fish in the loach family . It was a large genus with about 20 species. In 2004 Maurice Kottelat proposed in his paper to divide the genus into four related genera based on fish appearance and locality:* Botia for Indian loaches .*...
), betta
Betta
Betta is a large genus of small, often colorful, freshwater ray-finned fishes in the gourami family . The type species is B. picta, the spotted betta.By far the best known Betta species, however, is B...
s, crayfish
Crayfish
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...
, and most gourami
Gourami
Gouramis are a family, Osphronemidae, of freshwater perciform fishes. The fish are native to Asia, from Pakistan and India to the Malay Archipelago and north-easterly towards Korea. The name "gourami" is also used for fish of the families Helostomatidae and Anabantidae. "Gouramis" is an example of...
s—though many other fish will also consume snail meat. The larger apple snail will also prey upon ramshorn snails.
Good fish roommates for snails include, but are not limited to, danios, guppies, White Cloud Mountain Minnows
White Cloud Mountain minnow
The White Cloud Mountain minnow is a hardy, species of freshwater fish and coldwater fish often kept in aquaria.These creatures are brilliant for children as they are very easy to look after. The species is a member of the carp family of order Cypriniformes, native to China...
, neon tetra
Neon tetra
The neon tetra is a freshwater fish of the characin family of order Characiformes. The type species of its genus, it is native to blackwater or clearwater streams in southeastern Colombia, eastern Peru, and western Brazil, including the tributaries of the Solimões where the water is between...
s, and cory catfish
Corydoras
Members of the South American Corydoras genus are freshwater temperate and tropical catfish in the armored catfish family , and are commonly referred to as corydorases, cories, or cory catfish.-Taxonomy:...
. All of these are non-aggressive fish that cohabitate easily with snails.
One should also be aware that red ramshorn snails are able to carry various parasitic flukes, which can be transmitted to fish, or humans. Most of these flukes require intermediate host
Host (biology)
In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...
s, so that leaving the snails by themselves for a month or so will eliminate the disease.
If the population is kept to a manageable size, ramshorn snails can be good tank cleaners. They eat algae and dead or dying plants generally, so they can be useful. However, if they breed too prolifically they can become a nuisance. In warm climates (such as those in mainland Australia or the southern United states) they much prefer ponds, especially outdoor ponds. Algae, dead leaves that sink to the bottom, general grime and dead animals can be a problem as they foul the water. Ramshorn snails eat all of these things. They do breed more prolifically in ponds because there is more food but they aren't as noticeable in a pond as they are in a tank.
Role as aquarium pest
Most ramshorn snails are considered minor aquarium pests. They may arrive in a tank as eggEgg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
bundles hidden in newly acquired plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s. Although their red color may make them somewhat interesting aquarium subjects, their hermaphroditic
Hermaphrodite
In biology, a hermaphrodite is an organism that has reproductive organs normally associated with both male and female sexes.Many taxonomic groups of animals do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both...
ability to breed prolifically from any two specimens can make them troublesome.
Common practices include treating plants to prevent introduction, various manual methods of control, introducing the snail-eating animals listed earlier, and poisoning the snails.
Soaking the plants in various chemicals may kill off the snails and their eggs. A 10 minute bath in a solution of 20 parts water to 1 part chlorine bleach
Bleach
Bleach refers to a number of chemicals that remove color, whiten, or disinfect, often via oxidation. Common chemical bleaches include household chlorine bleach , lye, oxygen bleach , and bleaching powder...
has been suggested for hardier plants, followed by soaking in water containing a dechlorinating agent. A more gentle treatment calls for 5-10 tablespoons of alum
Alum
Alum is both a specific chemical compound and a class of chemical compounds. The specific compound is the hydrated potassium aluminium sulfate with the formula KAl2.12H2O. The wider class of compounds known as alums have the related empirical formula, AB2.12H2O.-Chemical properties:Alums are...
to 1 gallon of water for 2–3 days. A safer alternative may be placing the plants in a quarantine
Quarantine
Quarantine is compulsory isolation, typically to contain the spread of something considered dangerous, often but not always disease. The word comes from the Italian quarantena, meaning forty-day period....
tank, and adding snail poisons to that tank rather than the main show tank.
Manual methods include baiting the snails with lettuce (run it under hot water first and leave overnight), cucumber
Cucumber
The cucumber is a widely cultivated plant in the gourd family Cucurbitaceae, which includes squash, and in the same genus as the muskmelon. The plant is a creeping vine which bears cylindrical edible fruit when ripe. There are three main varieties of cucumber: "slicing", "pickling", and...
slices, or food pellets. These may be left out in the open, and removed with their snails, or kept in some container, such as a film canister weighed down with a pebble, and containing holes drilled in it. Crushing the snails by hand as they appear can also effectively limit their population; most ramshorn shells are fragile enough that this is quite easily done.
Snail poisons are generally considered to be a last resort, as most of them are copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
-based and are potentially toxic to plants and fish and particularly dangerous to other invertebrates. Even new safer chemicals that do not harm the other aquarium inhabitants may cause damage if large numbers of dead snails are allowed to decompose. For this reason, it is best to reduce the snail population by other means as much as possible before resorting to poisons, and to do frequent water changes afterwards. Some also recommend adding ammonium
Ammonium
The ammonium cation is a positively charged polyatomic cation with the chemical formula NH. It is formed by the protonation of ammonia...
protection to the tank. Zeolite chips, and various liquid products such as amquel may help in this area.
"Giant ramshorn" snails
Totally unrelated to these ramshorn snails is the species Marisa cornuarietisMarisa cornuarietis
Marisa cornuarietis, common name the giant ramshorn snail, is a species of large freshwater snail with an operculum, an aquatic gastropod mollusk in the family Ampullariidae, the apple snail family....
, which is often sold at pet stores under the name "Columbian ramshorn" or "giant ramshorn" snail. This species is actually a kind of apple snail, albeit one with a planispiral shell. They are distinguished by having an operculum by which they can close themselves into their shell, two pairs of tentacles, separate genders, and a siphon on the left side.
Its shell is yellowish, with brown stripes running the length of the shell. These apple snails lay gelatinous masses of eggs on submerged portions of plants. They can grow to up to four centimeters in size. They generally will not become a pest, although they can consume large amounts of plant matter.
External links
- Ramshorn Snails on The Aquarium Wiki