The National Aquarium (formerly known as the National Aquarium in Baltimore) is a non-profit public aquarium located at 501 E Pratt Street in the Inner Harbor area of Baltimore, Maryland in the United States.

Constructed during a period of urban renewal in Baltimore, the aquarium opened on August 8, 1981.

The aquarium has an annual attendance of 1.5 million.

The Aquarium holds more than of water, and has more than 17,000 specimens representing over 750 species.

In 2003, the National Aquarium and the independent National Aquarium in Washington joined as one National Aquarium.

The National Aquarium's mission is to inspire conservation of the world's aquatic treasures.

The aquarium's stated vision is to confront pressing issues facing global aquatic habitats through pioneering science, conservation, and educational programming.

Turtles are reptiles of the order Testudines (or Chelonii) characterised by a special bony or cartilaginous shell developed from their ribs and acting as a shield.

"Turtle" may refer to the order as a whole (American English) or to fresh-water and sea-dwelling testudines (British English).

Dolphins are a widely distributed and diverse group of aquatic mammals.

They are an informal grouping within the order Cetacea, excluding whales and porpoises, so to zoologists the grouping is paraphyletic.

The dolphins comprise the extant families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the new world river dolphins), and Pontoporiidae (the brackish dolphins), and the extinct Lipotidae (baiji or Chinese river dolphin).

There are 40 extant species of dolphins.

Dolphins, alongside other cetaceans, belong to the clade Cetartiodactyla with even-toed ungulates.

Their closest living relatives are the hippopotamuses, having diverged about 40 million years ago.

Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head.

Modern sharks are classified within the clade Selachimorpha (or Selachii) and are the sister group to the rays.

However, the term "shark" has also been used for extinct members of the subclass Elasmobranchii outside the Selachimorpha, such as Cladoselache and Xenacanthus, as well as other Chondrichthyes such as the holocephalid eugenedontidans.

Under this broader definition, the earliest known sharks date back to more than 420 million years ago.

Acanthodians are often referred to as "spiny sharks"; though they are not part of Chondrichthyes proper, they are a paraphyletic assemblage leading to cartilaginous fish as a whole.

An alligator is a crocodilian in the genus Alligator of the family Alligatoridae.

The two living species are the American alligator (A.

mississippiensis) and the Chinese alligator (A.

sinensis).

In addition, several extinct species of alligator are known from fossil remains.

Alligators first appeared during the Paleocene epoch about 37 million years ago.