Aquatic Animal

An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life.[1] Some examples of invertebrates are coelenterates. This phylum consists of jellyfish, anemones, corals, and hydras. Another type of invertebrate aquatic animal is the annelids which are segmented worms. There are three different classes they are polychaetes, oligochaetes, and hirudinea.[2] It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that live in them can be categorized as aquatic (water) or terrestrial (land). Animals that move readily from water to land and vice versa are referred to as amphibians. When animals live in water, they have special adaptations to help them survive in an aquatic habitat. The more time the animal spends in the water the quicker they adapt to their new habitat.

There are numerous ways that an aquatic animal can adapt to their habitat. The term aquatic can in theory be applied to animals that live in either freshwater (freshwater animals) or saltwater (seawater animals). However, the adjective marine is most commonly used for animals that live in saltwater, i.e. in oceans, seas, etc. Invasive aquatic animals require a water habitat, but do not necessarily have to live entirely in water.[3] Aquatic animals (especially freshwater animals) are often of special concern to conservationists because of the fragility of their environments. Aquatic animals are subject to pressure from overfishing, destructive fishing, marine pollution and climate change.

[edit]Air breathing aquatic animals
In addition to water breathing animals, e.g., fishes, mollusks etc., the term “aquatic animal” can be applied to air-breathing aquatic or sea mammals such as those in the orderCetacea (whales), which cannot survive on land, as well as four-footed mammals like the river otter (Lontra canadensis) and beavers (family Castoridae). Aquatic animals include for example the seabirds, such as gulls (family Laridae), pelicans (family Pelecanidae), and albatrosses (family Diomedeidae), and most of theAnseriformes (ducks, swans and geese). Amphibious and amphibiotic animals, like frogs (the order Anura), while they do require water, are separated into their own environmental classification. The majority of amphibians (class Amphibia) have an aquatic larval stage, like a tadpole, but then live as terrestrial adults, and may return to the water to mate. Certain fish also evolved to breathe air to survive oxygen-deprived water, such as arapaima (family Osteoglossidae) and walking catfish (Clariidae) Brine Shrimp

Brine shrimp are one of the most common live foods that you can use. They are something you can culture and grow yourself. To culture them you buy the eggs (cysts) in dried form. The directions for hatching are usually on the container, but here are abbreviated instructions. You can use any type of clear plastic or glass container. Because most hobbyist do not need a large volume of brine shrimp, a 2-5 gallon size container will work well. If the container has a wide open top, you will want to design a cover with a small hole in the center to fit your airhose through. This cover will help prevent overspray. Fill it 3/4 full with saltwater, add an airstone for movement of the water, add a small quantity of eggs (1 or 2 teaspoons), keep the temperature at about 75-80 degrees and add some light (preferably sunlight). Depending on the quality of the eggs, hatching will occur in 24-48 hours.