Clams: Characteristics, properties, reproduction and more

If you are one of those people who just like marine species, you have surely had more than once clams on your plate. Now, it’s time to know the history of this delicious mollusk.

clams: diffferent types of clams

It’s  known that clams were already in the seas, more than one hundred thousand million  years ago; since in the same way that the urchins and snails, their fossils were found in the oceans,  of  what today is known as Murcia, in Spain.

Likewise, remains of these bivalves were also found in the caves where the first inhabitants were presumed to have lived.

Clams: Main Characteristics

This is the common name of a large number of bivalves, that usually live in the sea. These mollusks are characterized by having a flattened body, with two shells joined on their back, which cover completely their body .

This last characteristic, is quite related to their name:  they have two shells joined together.

In addition, we should also mention that their name comes from Latin molluscus, which means soft; which is the main reason of being covered by protective shells.

These layers are calcareous and hard, being generally very similar to each other.

The valves or shells are usually oval; and are joined by a band called ligament, which unlike the shell; is not calcified, but rather is constituted of an elastic protein.

Although sometimes it is very difficult to perceive, they have teeth and channels that fit into others; similar to the other shell, to prevent them from moving, and the clam to open.

The shell is thin, and it has a protuberance on its dorsal part called umbo. Its central portion is convex, and has very fine ridges, which can be felt, and visually appreciated.

The shells of the clams vary a lot.  Some of them  are dark gray in color, some others are grayish , with brown spot; even there are also specimens  with brown lines on a yellowish white background.

Clams have a very underdeveloped head, the same way than their sensory organs; they have gills that serve for gaseous exchange, and sometimes they use them as filters to collect the food.

These mollusks lack eyes and brains; but their heart, mouth, rectum and circulatory system are surrounded by blood and water, from which they obtain nutrients and oxygen.


Clams are small,  reaching between twenty-five and fifty millimeters in lenght, at most. Their  weight  varies between twenty and fifty grams. Their body is composed of visceral mass, where the digestive, reproductive, excretory, and heart systems; are located.

The head-foot, where there are two tentacles; the mouth and teeth used to scrape the food, the foot that is the structure employed for moving, are the others components of their bodies. Moreover, the mantle is the surface that produces the shell, and where the clam’s breathing occurs.

let´s start knowing more about these curious creatures

Properties Of Clams

The clam is the shellfish with the lowest level of fat in its composition. It provides forty-seven calories per hundred grams of edible portion. This fact makes of them, an ideal food for weight loss diets. In addition they have a high content of minerals and vitamins.

The main vitamins provided by the clams are listed  below:

B3, also known as niacin:

This is a vitamin that is soluble in water, which helps grabbing the nutrients in the body, since  as it regulates the formation of red blood cells, as well as the production of sex hormones and synthesis of genetic material.

When we consume clams, the regulation of high cholesterol is guaranteed, since niacin reduces levels of LDL and triglycerides in the blood. So contrary, the HDL cholesterol level increase. This in turn helps prevent atherosclerosis.

It’s  believed that a diet rich in Carril clam  , could help to delay the dependence of insulin in type 1 diabetes. Likewise, it has been proven that the consumption of clams , improves  the symptoms of arthritis; increasing the mobility of the articulations., reducing this way the  consumption of non-steroidal anti-inflammatories.

According to the most recent research, it has been shown that the consumption of clams in the basic diet of people; considerably reduces the risk of suffering Alzheimer’s disease, thanks to the presence of niacin in them. In addition, it is believed that it can be a palliative to combat acne, and prevent skin cancer.

Vitamin A

Unlike vitamin B3, vitamin A is fat-soluble, thus it contributes to the generation and maintenance of the skin, mucous membranes, and bone system. By including clams in the basic diet, active defenses are maintained, making it less likely to contract an infectious disease, such as colds, pharyngitis, or bronchitis.

Thanks to the presence of this vitamin, the consumption of clams facilitates the multiplication of epidermal cells, fixes damaged tissues, and prevents the dryness of the skin, periodically renewing its cells

Vitamin A protects the skin, and the consumption of clams prevents dermatitis, acne, psoriasis, herpes, and eczema; that’s why people who consume more clams in their basic diet, are generally healthier, and tend to have fewer wrinkles.

The vitamin A present in clams, acts as an antioxidant on our skin.

In addition to being excellent for our skin, the consumption of clams also helps in strengthening the bones and teeth; especially when children are growing.

Also, clams can prevent some eye conditions such as glaucoma and cataracts, so when people suffer from conjunctivitis, they include clams in their basic diet. And the most important thing in this case, when you have a balanced diet, which includes the consumption of clams; you can prevent cancer of the stomach, chest, lung, and mouth; besides being indicated for people who are undergoing chemotherapy.

Thanks to the presence of vitamins in clams, the consumption of this food not only helps strengthen the nails and hair, but also encourages their growth. And this mollusk is also advisable, when people suffer from ulcers, since it regenerates intestinal mucus.

In addition to vitamins, clams also contain a large amount of minerals that provide many benefits for humans.


This mineral  which is present in the clams, helps to preserve the health of our teeth, bones and heart. For this reason, clams are an excellent alternative for people who are prone to osteopenia and osteoporosis, because this mollusk enhances, bones´ strength and density.

It’s  believed that including clams in the basic diet; can control high blood pressure, and the symptoms of premenstrual syndrome, in women. Also the daily intake of clams, can prevent breast cancer in premenopausal women and even other types of cancer.

The low content of fat in clams,  has made of them a must have in  diets for weight loss.


This is another mineral present in the clams, which makes of them an essential nutrient for the human body. In addition to its high benefits, for the production of red blood cells; iron  also collaborates in the creation of muscle proteins, as well as in chemical changes of certain enzymes in our body.

Specialists recommendto consume clams since they can prevent anemia, reducing  the risks of suffering from fatigue or weakness.

Thus, iron also increases the corporal energy levels,  strengthens the immune system and improves the respiratory system..

Thus, we can conclude that clams are a food with high content of nutrients; primarily due to the presence of iron, which release oxygen through the cells of the body, and removes carbon dioxide. When we consume iron,   our immune system is strengthened, and our body remains full of energy.


The content of phosphorus  is one of the most important properties of clam, because this mineral not only helps in the formation of bones, but also in the proper performance of blood, kidneys, heart, and brain. Thus, it is very important to include clams in our basic diet, to avoid bone and body weakness, rickets, tooth decay and weakness, anxiety, numbness, and weight loss for no apparent reason.


This is another of the minerals present in clams, that like many others provides many health benefits, because it helps to keep our body young and vital,  at any age. Magnesium prevents  a large number of disease,  its consumption also stimulates the proper functioning of kidneys .

In the same way,  magnesium is also quite useful for mental balance; since it stimulates brain functions, as well as the cardiovascular system.

Thus, the consumption of clams prevents heart disease. Magnesium is also recommended for high performance athletes, because it combats cramps, as well as muscle fatigue.

Given the presence of magnesium in clams, these mollusk help to reduce cholesterol levels, to combat depression, dizziness and fatigue, and prevents the problems of colitis, constipation, and hemorrhoids.


This mineral which is also  present in clams, provides a large number of benefits for humans, since it’s  responsible for normalizing the balance of water in the body.  Potassium  also normalizes the contraction and relaxation of muscles, helping also on their proper functioning.

Given all these properties, the periodic consumption of clams helps regulate the water content of the cells and their movement, and alongwith sodium controlsthe amount and normal distribution of water in our body.  In the same way than vitamin A, potassium intervenes in the production of proteins,
Thanks to the potassium, calcium, and magnesium present in clams, this food regulates all cellular functions and contributes to the excitability of the heart, muscles and   nervous system.

Let´s learn more about the benefits of minerals


How Do Clams Reproduce?

The Clams in conjunction with  snails, and octopuses, make up the second biggest group of animals, being only surpassed by the arthropods. There are one hundred thousand (100.000) species of clams, as well as  seventy thousand fossils species. These mollusks have separate sexes, and they reproduce by  external fertilization.

Clams are hermaphrodites, which means they can be both male and female. They practice consecutive sexuality, so if in a season one of them acts as male, in the following season it will be the female.

The one who performs the function of female, releases between five and eight million ovules into the sea; depending of the time of year.

On the other hand, the male  releases two thousand six hundred million spermatozoa,   which fuse with the cells spread by the female, forming the eggs. Later, mobile  larvae come out  from the eggs,  becoming  part of the plankton, being exposed to water currents during several weeks.

This process takes place only when the water temperature exceeds 10 Celsius degrees. The gametes will only develop and ripen between the months of May and August, being held; until temperatures exceed 20 degrees Celsius.

Let´s watch this video to learn about clams spawning…

However , from the five or eight million eggs that spawns female clam, only one million larvae survive.

Growth of the Larvae

This growth depend on different factors, such as the temperature of the water, the salinity it has, the amount of food they can get, and above all, the changes that may arise in their habitat. Once they reach  a quarter or a third of a millimeter, the larvae submerge burying into  to the bottom , to begin their metamorphosis.

During this process the larvae lose their swimming organ, and develop the gills, becoming then in  shells, in few time.

How d0 hatcheries reproduce clams?

Since hatcheries need to produce clams  without any stop, because this represents loss of money for them, the managers accelerate the maturity of the clams, by raising the temperature of their habitat; and providing them with a suitable food ration.

They have achieved that clams reachsexual maturity in winter, long before than clams that live in the sea; since they require to extend the period so that during all the year the clams are available to spawn. Therefore, they are conditioned at high temperatures and more food rations, since young age.,

What do clams eat ?

It is believed that the first species of clams were only excavators of soft substrates, since the current entered through a space crossing the gills and exiting through a dorsal opening. In this process the cilia located in the gills,  were responsible for producing a current to remove the  particles retained in this area .

Once the clams adapted to dig and bury in the bottom, their bodies became lengthened   and their  mouths   recoiled;  so the radula disappeared, being replaced by   the labial palps that explore the substrate.

Due to the mucus in the labial palps, the particles adhere to it, and the cilia transport them to be selected before going through the mouth of the clam.

The clams feed basically on plankton, which they ingest through the filtration of the water. Thanks to this process, these mollusks can remain between fifteen and thirty centimeters buried in the seabed.

There is a type of clam that besides feeding on zooplankton, and detritus of other animals, can dig in trunks that have been thrown into the water, and feed on sawdust. Likewise, this mollusk has parasitic behaviors, so they can inhabit sea urchins, crustaceans, and starfish, feeding on their remains.

Now, enjoy this video


Where do Clam Inhabit?

Clams live in practically all the ecosystems of the whole world, since they are one of the most successful colonizers of the animal kingdom; they remain buried in the sand between fifteen and thirty centimeters, where they dig to hide in the sandy or muddy bottom.

In general, the clams live in marine environments, being the main exponents of the fauna in this ecosystem of the bottom of the ocean.

However, there are some clams that also inhabit freshwater.

These unique mollusks have different lifestyles, so while some of them are swimmers; others crawl in the sand and bury themselves in the muddy bottom of the ocean.


These mollusks are found in all the waters. In this sense, we should point out that the Atlantic coast, is the most populated area by yellow clams  in the world.  The English Channel and the Mediterranean Sea., also have a big population of these mollusk.

Freshwater Clams

These are mollusks with a life expectancy of up to ten years,  when they live in captivity. Like the sea clams,  the fresh water clams are also bivalves that originated in the freshwater basins of the European continent, and Western Asia. The Iberian Peninsula, is the most common location of the four species that exist

They are also known as pictorum, because in ancient times painters used their empty shells as color palettes. Nayade is another common denomination for these  clams; which in short time may be classified as an endangered species;  since their habitats are being destroyed,

The Freshwater Clams’ Main Characteristics

They are usually very small, reaching 15 cm in length at most. These clams, can live at  very low temperatures, even those that are close to freezing; but they have some difficulty adapting to high temperatures.

Freshwater clams feed by filtration since they have the amazing capacity to filter two liters of water per hour. This fact allows them  to feed on particles in suspension.

When these mollusks live in aquariums where there is enough life, they don´t  require any other type of food, other than what they obtain in it.

In the same way than the sea clams, freshwater clams have two symmetrical shells of different colors. These mollusks  are  very sensitive to toxic compounds such as copper.

So, when having a domestic aquarium, you should not introduce any object that has this  harmful compound to them, since it produces a sudden death,  for no apparent reason.


Since these mollusks   like to dig, the aquarium must have at least eight centimeters of substrate; or preferably sand or mud, so that the clam can dig burying itself in the substrate

It is very important to know, that you should never try to help the clams to bury, because only they know how to do it.

It is very common, that when people try to help clams to bury, they do it in inverted way, making the clam drowns.

In the same way, it is required to have carbonates in the aquarium water; because they are quite useful to maintain the proper conditions of the clams´  shells.

 What do freshwater clams eat?

These clams also feed by means of the filtration of the plankton and the detritus of other animals, when they are in their natural habitat. If there is enough life when they are in aquariums , clams won´t need any supplement, since they will eat what the ecosystem offer

As a result of the destruction and disappearance of their natural habitats, this genera is in decline. A big portion of the vegetation in their watersheds has been destroyed, due to construction works and pollution.

This situation promotes the extinction of the freshwater clams, as well as species that feed on them, such as sturgeons, salmon, and other predators.

For this reason, the gathering  of this species has been banned; because instead of doing them a favor, as some people could  think; they are doing a terrible damage, because even if you want to give them an environment very similar to their natural habitat, the clams are not going to be better than at home.

Curious facts about Clams

These are some curious facts, which you probably don’t know, despite having tasted a delicious dish of clams

    • Besides being used as a palette of colors by painters, their shells have also been used as trumpets, and to make ornaments.
    • They were also employed as coins, in ancient times
    • These animals do not emit any kind of sound, nor listen, nor taste.
    • There is a giant clam species that lives for two hundred years, and weighs three hundred kilograms.
    • These mollusks can move thanks to the ability to open and close their shells
    • The largest clam known was found in Iceland in 2006; and at the time of calculating its age, four hundred lines of growth were counted in its shell.
      The Geoduck clam is the largest burrowing mollusk in the world, being one of the oldest animals on the planet; it is believed that it can live a hundred and forty years, and one of the largest specimens, reached 7.5 kilograms of weight.

However, we can´t enjoy these wonderful creatures without learning first how to cook them…


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