Five groups that classify all living things
A group of animals within the animal kingdom
A group of animals within a pylum
A group of animals within a class
A group of animals within an order
Most widely used name for this species
The name of the animal in science
The place where something is found
What kind of foods the animal eats
How long (L) or tall (H) the animal is
|3cm - 15cm (1.2in - 6in)|
The measurement of how heavy the animal is
|50g - 200g (1.7oz - 7oz)|
|Number Of Species:|
The total number of recorded species
The average time the animal lives for
|1 - 3 years|
The likelihood of the animal becoming extinct
The colour of the animal's coat or markings
|Black. Brown, Yellow, Tan, Silver, White|
The protective layer of the animal
The preferred food of this animal
The specific area where the animal lives
|Reefs and rocky shores|
|Average Litter Size:|
The average number of babies born at once
The food that the animal gains energy from
|Plankton and Nutrients in Water|
Other animals that hunt and eat the animal
|Fish, Birds, Humans|
Characteristics unique to this animal
|Filter water through their hard shell|
The oyster is a sessile (immobile) mollusc that is commonly found clinging onto shipwrecks, debris and harbour walls around the world. Oysters are bivalve molluscs meaning that they are closely related to other animals such as scallops, clams and mussels.
Oysters are found in salt water environments all around the world but are more commonly found in more temperate regions where the shallows are richer in nutrients. Oysters are thought to be among the oldest animals on the planet although their exact evolutionary path remains unclear.
As with other molluscs, oysters filter water in and out of their protective shells so that their vulnerable bodies inside are never put in danger. The hard shell of the oyster is primarily made up of calcium.
Despite there being numerous different species of oyster, oysters are generally split up into four distinct groups, which are true oysters (the ones eaten by humans), pearl oysters (produce pearls), thorny oysters (also known as spiny oysters) and saddle oysters (have very thin shells).
Oysters are filter-feeders so collect their nutrients by taking in water and their gills filter and collect food that the stomach then digests, dispersing the remaining water out of its shell. Oysters are thought to be able to process up to 10 litres of water an hour so can vary in quality depending on the quality of the water.
Due to their small size and the fact that they don't move once they are adults, oysters are preyed upon by numerous different predators both in the sea and on the land. Humans, birds, marine mammals, sea turtles and various species of fish all prey upon the oyster.
Oysters have varying methods of reproduction. as some oyster species are hermaphrodites and some have separate sexes. Female oysters release millions of eggs into the water, where fertilization occurs externally. The oyster larvae develop within a matter of hours, and spend their first few weeks swimming around until they finally settle and attach themselves to objects, where they remain for the rest of their lives.
Today, although now commercially farmed, wild oysters are becoming rarer mainly due to increasing levels of pollution. Although many oysters have adapted to life in poor quality water, they are not as healthy as those oysters that are filtering water that is chemical-free.
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First Published: 17th May 2010, Last Updated: 8th November 2019
1. David Burnie, Dorling Kindersley (2008) Illustrated Encyclopedia Of Animals [Accessed at: 17 May 2010]
2. David Burnie, Kingfisher (2011) The Kingfisher Animal Encyclopedia [Accessed at: 01 Jan 2011]
3. Dorling Kindersley (2006) Dorling Kindersley Encyclopedia Of Animals [Accessed at: 17 May 2010]
4. Richard Mackay, University of California Press (2009) The Atlas Of Endangered Species [Accessed at: 17 May 2010]
5. Tom Jackson, Lorenz Books (2007) The World Encyclopedia Of Animals [Accessed at: 17 May 2010]