Brine shrimp are small shrimp that live in salt water. Brine shrimp are Artemia, a genus of aquatic crustacea which has changed little (externally) since the Triassic period. They can often be found in saltwater ponds and marshes, and cannot live very long in fresh water. Artemia avoid living with most types of predators, such as fish, because they live in waters of very high salinity: up to 25% (250 parts per thousand). The optimum for Artemia is 100 to 150 parts per thousand. The shrimp grow to be about one centimeter long. Females tend to be larger than males.
Brine shrimp circulatory and respiratory systems work together to remove extra salt from their body and distribute oxygen. They breathe through gills on their feet. The oxygen taken in is carried through the bloodstream. The heart pumps the blood around the body. Brine shrimp have a protein called hemoglobin in their blood. This helps the oxygen to be more efficiently transported to cells around the body. They need hemoglobin because oxygen levels can be very low in salty water. Then, the gills pump the excess salt, water, and carbon dioxide out of the body. Additional salt is pumped out through exocrine glands.
The brine shrimp's body is divided into main parts: the head, the thorax, and the abdomen. A hard exoskeleton covers the entire body. Inside this exoskeleton, which is made of chitin, is where the brine shrimp’s muscles are located. Their muscles are attached internally. They move by beating their tails and by the continuous movement of the legs along their body.
Their nervous systems consist of a brain and local nerves. Brine shrimp do not have spines, so they are considered invertebrates. Most of their actions, including swimming, digestion, and respiration, are controlled by local nerves. Brine shrimp have three eyes. They are born with the first one, which only senses light, and grow two more eyes mounted on stalks after they become adults.
Brine shrimp take in food though their mouth. The food then travels through their esophagus to their stomach, which is in the head. Then, the food travels to the intestine, a long tube that runs throughout the body. While in the intestine, food is broken down using enzymes. Blood vessels surround the intestine, and nutrients from the food pass through the intestine walls and are absorbed into the bloodstream. In their natural habitat, brine shrimp generally feed off algae, and other animals, in turn, feed off them.
Female and male brine shrimp have different reproductive systems, although they are similar in some ways. The female reproductive organs consist of ovaries and an ovisac. These are used to produce and store their eggs. The male reproductive organs are testes and a penis. Females can fertilize their eggs in two ways. The first way involves both the male and female brine shrimp. The male would help fertilize the egg in the female's body. This process is known as copulation. The other way only involves a female brine shrimp. She is able to fertilize her own egg. This is the more common process known as parthenogenesis. If the eggs' environment is not healthy enough for the brine shrimp eggs to hatch, they will become cysts (dormant eggs) and will hatch once in the appropriate environment. If the brine shrimp eggs are in an ideal environment, they will be able to hatch into nauplii, or recently hatched brine shrimp larvae that can swim in water. From there, they become sub-adults or juveniles, meaning that they are growing larger and more mature. Finally they will enter adulthood, meaning they have finished growing.
The term 'Sea-Monkey' is a trademark used to sell them as pets.
References[change | edit source]
- Coolidge-Stolz M.D.E. et al. 2007. Life Science. Boston: Pearson.
- Sorgeloos P, P. Dhert & P. Candreva 2001. Use of the brine shrimp, Artemia spp. in marine fish larviculture. Aquaculture 200: 147–159