Turtles are reptiles of the order Testudines characterized by a special bony or cartilaginous shell developed from their ribs and acting as a shield. "Turtle" may refer to fresh-water and sea-dwelling testudines. The order Testudines includes both extinct species; the earliest known members of this group date from the Middle Jurassic, making turtles one of the oldest reptile groups and a more ancient group than snakes or crocodilians. Of the 356 known species alive today, some are endangered. Turtles are ectotherms—animals called cold-blooded—meaning that their internal temperature varies according to the ambient environment. However, because of their high metabolic rate, leatherback sea turtles have a body temperature, noticeably higher than that of the surrounding water. Turtles are classified as amniotes, along with other reptiles and mammals. Like other amniotes, turtles breathe air and do not lay eggs underwater, although many species live in or around water. Differences exist in usage of the common terms turtle and terrapin, depending on the variety of English being used.

These terms do not reflect precise biological or taxonomic distinctions. Turtle may either refer to the order as a whole, or to particular turtles that make up a form taxon, not monophyletic, or may be limited to only aquatic species. Tortoise refers to any land-dwelling, non-swimming chelonian. Terrapin is used to describe several species of small, hard-shell turtles those found in brackish waters. In North America, all chelonians are called turtles. Tortoise is used only in reference to terrestrial turtles or, more narrowly, only those members of Testudinidae, the family of modern land tortoises. Terrapin may refer to small semi-aquatic turtles that live in fresh and brackish water, in particular the diamondback terrapin. Although the members of the genus Terrapene dwell on land, they are referred to as box turtles rather than tortoises; the American Society of Ichthyologists and Herpetologists uses "turtle" to describe all species of the order Testudines, regardless of whether they are land-dwelling or sea-dwelling, uses "tortoise" as a more specific term for slow-moving terrestrial species.

In the United Kingdom, the word turtle is used for water-dwelling species, including ones known in the US as terrapins, but not for terrestrial species, which are known only as tortoises. The word chelonian is popular among veterinarians and conservationists working with these animals as a catch-all name for any member of the superorder Chelonia, which includes all turtles living and extinct, as well as their immediate ancestors. Chelonia is based on the Greek word for χελώνη chelone. Testudines, on the other hand, is based on the Latin word for testudo. Terrapin comes from an Algonquian word for turtle; some languages do not have this distinction. For example, in Spanish, the word tortuga is used for turtles and terrapins. A sea-dwelling turtle is tortuga marina, a freshwater species tortuga de río, a tortoise tortuga terrestre; the largest living chelonian is the leatherback sea turtle, which reaches a shell length of 200 cm and can reach a weight of over 900 kg. Freshwater turtles are smaller, but with the largest species, the Asian softshell turtle Pelochelys cantorii, a few individuals have been reported up to 200 cm.

This dwarfs the better-known alligator snapping turtle, the largest chelonian in North America, which attains a shell length of up to 80 cm and weighs as much as 113.4 kg. Giant tortoises of the genera Geochelone and others were widely distributed around the world into prehistoric times, are known to have existed in North and South America and Africa, they became extinct at the same time as the appearance of man, it is assumed humans hunted them for food. The only surviving giant tortoises are on the Seychelles and Galápagos Islands and can grow to over 130 cm in length, weigh about 300 kg; the largest chelonian was Archelon ischyros, a Late Cretaceous sea turtle known to have been up to 4.6 m long. The smallest turtle is the speckled padloper tortoise of South Africa, it weighs about 140 g. Two other species of small turtles are the American mud turtles and musk turtles that live in an area that ranges from Canada to South America; the shell length of many species in this group is less than 13 cm in length.

Turtles are divided according to how they retract their necks into their shells. The mechanism of neck retraction differs phylogenetically: the suborder Pleurodira retracts laterally to the side, anterior to shoulder girdles, while the suborder Cryptodira retracts straight back, between shoulder girdles; these motions are due to the morphology and arrangement of cervical vertebrae. Of all recent turtles, the cervical column consists of nine joints and eight vertebrae, which are individually independent. Since these vertebrae are not fused and are rounded, the neck is more flexible, being able to bend in the backwards and sideways directions; the primary function and evolutionary implication of neck retraction is thought to be for feeding rather than protection. Neck retraction and reciprocal extension allows the turtle to reach out further to capture prey while swimming. Neck expansion create

USS Spirea was a 409-ton steamer acquired by the Union Navy towards the end of the American Civil War. The Union Navy placed Spirea, with a crew of 65 sailors and naval officers, in service as a gunship and assigned her to blockade operations against the Confederate States of America, placing her as a gunboat on the Gulf of Mexico coast of Florida where she spent her entire U. S. Navy career. Spirea—a twin-screw steamer built in 1864 at Fair Haven and sister ship of USS Hibiscus —was purchased by the Union Navy at New York City on 30 December 1864 from S. M. Pook. Spirea was ordered to join the East Gulf Blockading Squadron at Key West, Florida, in early January 1865. On 23 February, she led an expedition up the St. Marks River to land Union Army troops for an attack on Tallahassee, Florida. Spirea and two other ships ran aground, but she was refloated and patrolled off St. Marks, until 1 May when she joined the blockade off Apalachicola, Florida. Two weeks she returned to St. Marks. After the end of the Civil War, Spirea remained on duty in the Gulf of Mexico until she sailed early in August.

Spirea was decommissioned at the New York Navy Yard on 23 August 1865 and was sold at public auction at New York City on 5 October 1866. The screw steamer was documented as Sappho on 30 January 1867 for operation out of New York City, she was lost in 1867, but details of her demise have not been found. United States Navy List of United States Navy ships This article incorporates text from the public domain Dictionary of American Naval Fighting Ships; the entry can be found here

Przemysław Niemiec is a Polish former road racing cyclist, who rode professionally between 2002 and 2018 for the Amore & Vita–Beretta, Miche and UAE Team Emirates squads. He made his professional debut in 2002 for the team Vita -- Beretta. Born in Oświęcim, Niemiec won the 2006 edition of the Tour of Tuscany, he has won a number of stages of the Route du Sud and finished sixteenth alongside the leading competitors at the 2008 Summer Olympics. In 2013, Niemiec had top ten finishes in many stage races including the Giro Del Trentino, the Volta a Catalunya, in the Tirreno Adriactico. After finishing 3rd in the 2013 Giro del Trentino, Niemiec was selected to Team Lampre squad at the Giro d'Italia and he rode in support of Michele Scarponi, where he had a solid 6th-place finish, he won the biggest victory of his career at that point at the 2014 Vuelta a España. He won solo on the final climb to Lagos de Covedonga. Media related to Przemysław Niemiec at Wikimedia Commons Przemysław Niemiec at Cycling Archives