Are Clams Born With Shells? How Do Clams Reproduce?

Clams are marine mollusks known for their burrowing activities. They live in freshwater, sand, or mud, with a soft un-segmented body typically enclosed in a shell. Most people are curious about clams shells and often ask if clams are born with their shells.

So, Are clams born with shells? No, clams are not born with shells. After hatching, they swim freely as larvae, then secrete a hard shell before metamorphosis. 

How Do Clams Reproduce?

As shell dwellers, with only a single limb (retractable with similarities to a tongue), these make reproduction seem impossible among clam species. However, clams do reproduce, and millions of them are born yearly. 

The clam life cycle comprises several stages before they act and look like actual clams. At the juvenile stage of their development, all clams are male, this is because their sperm is a lot smaller, requiring lesser resources to produce in comparison to their eggs. 

While juvenile males lack the metabolic resources needed for egg production, they also cannot accommodate eggs. However, this seizes to be a problem once they become adults, with sufficient energy for production, instead of growing.  

Depending on species and location, clams begin to make babies when the water temperature is warm enough, and this could be Fall, summer, or spring. For the Northern Quahog Clam species, or The hard clam or Mercenaria mercenaria, they begin making babies in early summer/spring when the water temperature is 68F.

Spawning is performed by males, and they do this by releasing eggs into the ocean. The goal is to target eggs produced by their larger species that are fully developed into females.  

After the sperm is released, the millions of gametes combine in the water where fertilization takes place. The cells of each egg will only divide when sperm comes into contact with an egg, forming an embryo that grows into a morula, cell-like balls that bear similarity with a mulberry. 

After one or two days, cilia begin to grow on the creature, transforming it into a trocophore, a free-swimming larva. 

Metamorphosis takes place, as the larva adds a foot and a shell, becoming a veliger that continues to swim and eat plankton for the next couple of weeks.  

The formation of the body into a clam-like state begins at the veliger stage, with one side rounded (the opening part of the clam), and the other side straight (the hinge). 

The bivalve appearance becomes apparent following the veliger stage, with shell hardened and foot developed ( called a pediveliger).  

 The total time to reach this juvenile phase is between 8 days and two weeks. The heavy and stiff juvenile then sinks to the ocean floor, a process known as the settling stage. 

Young clams quickly learn to use their foot in burrowing through sand and a siphon for feeding. The siphon extends from the shell, and in most cases, clams remain under the sand, while their siphon reaches out into the water to filter-feed plankton. 

Above sand level, clams can intelligently detect predators by their shadows with the help of their photoreceptors, which leaves them dashing for cover. Hidden away from imminent danger, they wait until it is time for yet another spawning. 

Statistically, about 10% of fertilized eggs reach the juvenile stage, if a clam does not get eaten, it can live for up to 30 years. They can grow up to 4 inches across before developing into lady clam.  

How Do Clams Produce Shells?

Clams produce their shell by extracting several forms of calcium deposits abundant in the water. They store the calcium for weeks and sometimes months, then secrete the material in some sort of loose glue while adding bits to the rim of the shell as the clam develops. 

The material then hardens with a similar consistency as the rest of the shell, and you can tell how old the clam is by examining the ridges on the shell. 

How Many Eggs Does a Clam Produce?

When it comes to egg production among clams, studies reveal that factors such as temperature and size of females largely influence egg production. The larger a female clam is, the more eggs she is capable of producing. 

So, how many eggs does a clam produce?  At the peak of spawning, tow-inch clams can release up to 2.1 million viable eggs, as opposed to the three-inch clams which release 3.6 million eggs. 

Final Thoughts: Are clams born with shells? 

Clams are one of the many wonders of the marine world and they are not born with their shells. The shells are only formed after hatching. 

Related Questions

 What are baby clams called? Baby clams are known as littlenecks.

How do clams make pearls? Clams produce pearls by secreting chemicals such as calcium carbonate (CACO3) and conchiolin to harden and trap parasites that irritate them. The production of pearls is actually a defense mechanism.  

Do clams reproduce asexually? Yes, clams reproduce asexually, male clams release sperm into the ocean to meet and fertilize eggs produces by larger females.

See Also

Do Snails Poop? What Does Snail Poop Like? (+pictures)

Do Snails Bite? The Complete Guide