What Do Oysters Eat? Interesting Facts For Curious Kids

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There are 200 different types of oysters.

All of these oysters develop from five main oyster species. They are Kumamoto oysters (Crassotrea sikamea), Pacific oysters (Crassotrea gigas), Atlantic oysters (Crassotrea virginica), European flat oysters (Ostrea edulis), and Olympia oysters (Ostrea lurids or Ostre conchaphila).

Some species of oysters are good and will have a specific low tide smell. Such oysters are rarely found. Oysters have an effect on the entire ecosystem. Apart from clearing algae and creating habitats for other species, they also pass on nutrients to other organisms. The eastern American oyster and the Pacific oyster are the most famous oysters. The American oyster lives in the Atlantic waters while the Pacific oyster is mainly found in regions from Japan to Washington. They are some of the most harvested oysters. Oysters reproduce by internal fertilization. Female oysters can lay 50-100 million eggs. The oyster larvae attach themselves to a suitable surface and are called spat after getting attached. Baby oysters are sexually matured within a year. Oyster beds are surfaces on which oysters breed. Oysters can live up to 20 years under human care. Did you know, a study confirming the increase in production of testosterone due to the presence of two amino acids named the D aspartic acid and N methyl D aspartate present in oysters was published in 2005?

We have curated a bunch of interesting facts about oysters and what they eat. Do not miss out on them. You can also check out our other related articles about what parrots eat and what prairie dogs eat.

What are oysters?

Oysters are bivalve mollusks that have been consumed by humans since the Roman Empire period. The word oyster is derived from the Greek word ostreon, which was later changed into oistre. They are found in brackish and saltwater sources. Oysters are filter feeders that are energetic at water temperatures over 50 F (10 C). Some oysters are even capable of fertilizing their own eggs as they have both male and female reproductive systems containing eggs as well as sperms. Oyster reefs or beds are terms used to refer to a collection of oysters. Oysters are keystone species, meaning they have a huge effect throughout their natural ecosystems and support numerous species. Oyster shells deposited in the sea act as natural habitats for several marine animals. Oysters are classified into three categories, namely pearl oysters, true oysters, and other oysters.

Pearl Oysters: A pearl oyster is part of a group of bivalves that produce quality pearls. They are used for the production of natural and artificial pearls. They naturally produce pearls by covering foreign particles with nacre, which is also known as mother-of-pearl. There are different colors and shapes of pearls produced by pearl oysters.

True Oysters: Members of the Ostreidae family are known as true oysters. Members of the Ostrea, Crassostre, and Ostreola are the most common and famous bivalves. Contrary to belief true oysters cannot produce gem-quality pearls. They are predominantly used as highly-priced food that can be eaten both in cooked and uncooked forms.

Other Oysters: Apart from true oysters and pearl oysters, several other bivalve mollusks also have the word oyster in their names. This is either because of their taste or their similar appearance to true oysters. Thorny oysters belonging to the Spondylus genus, saddle oysters who are members of the Anomiidae family, and Dimydrian oysters who belong to the Dimyidae family are some of the other oysters.

Oysters have phenomenal nutritional values. They are packed with vitamin A, vitamin B12, zinc, calcium, and selenium. You can obtain 110 kilocalories of energy from just a dozen of raw oysters. All edible oysters belong to the Ostreidae family. Fresh oysters must be cooked or consumed when they are alive. You should not eat dead oysters unless they are deliberately killed and stored in cold temperatures.

What do oysters eat in the sea?

Oysters are filter feeders. This means they obtain their food by filtering water present in their habitat. They are also referred to as bottom feeders since they live on sea beds and scavenge.

Phytoplanktons are the main source of nutrition for oysters. Oysters also eat phosphates, plankton, detritus, bacteria, and dissolved organic material such as leaf litter and bits of seagrasses. They filter water by using their gills and trap the small bits of algae suspended in floating water. Though oysters don't have brains, they still know what they should and should consume. Oysters can potentially starve if they are exposed to the wrong kind of algae. Oysters are vegetarians that are finicky about what they eat. Things like the oysters' shape, shell strength, color, taste, and growth rates are determined by the food they consume. Some oysters found in estuaries are seen consuming the wrong kind of food.

Dermo, a parasite, is a great threat to the oyster industry, as it kills many oysters.

Eastern oysters are an extremely important part of the Chesapeake Bay ecosystem.

What do wild oysters eat?

Wild oysters survive by extracting algae and other food particles.

Do oysters have poop in them is one of the other popular questions that are related to oysters. Yes, oysters poop. When the oyster digests its food, the waste will get accumulated in a layer within the shell. Apart from the food waste, substances known as pseudo-feces also get accumulated in the shell. (pseudo-feces refers to indigestible particles like huge chunks of food and sand). The oyster stores both the waste matter together after mucus coats them. From time to time, the oyster excretes its waste matter by clapping the shell together. This forces water to enter, which washes all the waste away.

Did you know, oysters taste more delicious in winter? For at least 4,000 years, people have practiced an old tradition of not eating wild oysters in months other than September, October, November, December, January, February, March, and April. This is called the R rule. Oysters without the R letter are known to cause food poisoning and other stomach issues.

Do oysters eat algae?

Oysters are detritivores that eat algae. (Detritivore refers to heterotrophs that feed on dead and decaying plant or animal matter.) When there are more algae in the water, oyster gets more food.

Bob Rheault says that the American oyster has the ability to split up equally sized algal bits even when combined with a thick silt soup. High-laden silt water is where most organisms suffocate due to their fouled gills. However, due to the exceptional ability of these oysters to separate algae, they are versatile and will thrive even in such waters. By consuming algae, oysters improve the water quality in various water sources. They can clean 1.5 gal per hour (5 l per hour).

There are a few ill effects of eating oysters. They do not always cause health issues, but if an oyster is not cooked properly, it can pass on vibrio infection, norovirus infection, and hepatitis A. Germs in the oyster and other heavy metals do not get killed or washed away when they are not cooked properly causing these infections. Oysters can also cause food poisoning and diarrhea in some people. Around 100 people die every year in the United States after contracting vibrio infection from oysters and about 80,000 people are infected. Humans are prone to getting these infections in the summer months. Eating too many oysters can also be harmful. Zinc in oysters competes with absorption with other nutrients like iron and copper, resulting in copper and iron deficiencies and affecting the overall health. Several health organizations advise people to consume cooked oysters alone to avoid contracting such fatal infections.

Did You Know...

Oysters do not have a central nervous system. Therefore, it is said that they do not feel pain when they are being cooked. This is the main reason why some vegans can comfortably eat oysters.

Oysters escape predators like crabs, humans, sea birds, and starfish by using their eyes. Yes, oysters have eyes all over their bodies.

Oysters are aphrodisiacs. Studies have concluded that oysters trigger sexual desire in both men and women due to the presence of certain amino acids.

Oysters clean water by taking in water and separating the algae particles. They then spit the water back.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for what do oysters eat then why not take a look at what quails eat, or oyster facts?


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