Question: what is Eucritta and the Creature from the Black lagoon?

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List of Black Lagoon episodes: "Black Lagoon" is an anime series adapted from the titular manga series by Rei Hiroe.  Directed by Sunao Katabuchi and produced by Madhouse, it consists of two seasons produced for television, and one in original video animation format.  The two seasons, each twelve episodes in length, are titled "Black Lagoon"— which was co-produced by Shogakukan—and "Black Lagoon: The Second Barrage".  The OVA, titled "Black Lagoon: Roberta's Blood Trail", consists of only five episodes.  The series follows the adventures of Rokuro "Rock" Okajima, a Japanese businessman who is abducted by, and eventually joins a group of outlaws known as the "Lagoon Company".

Richard Denning: Richard Denning (March 27, 1914 – October 11, 1998) was an American actor best known for starring in science fiction films of the 1950s, including "Unknown Island" (1948), "Creature from the Black Lagoon" (1954), "Target Earth" (1954), "Day the World Ended" (1955), "Creature with the Atom Brain" (1955), and "The Black Scorpion" (1957).  Denning also appeared in the film "An Affair to Remember" (1957) with Cary Grant and on radio with Lucille Ball, as George and Liz Cooper, in "My Favorite Husband" (1948–1951), the forerunner of television's "I Love Lucy".  His character's name on CBS Radio's "My Favorite Husband" was changed from George Cugat to George Cooper later in 1948.  A television version of "My Favorite Husband" (1953-1955) was broadcast on CBS for two seasons during the tenure of "I Love Lucy".

Ricou Browning: Ricou Browning (born November 23, 1930) is an American film director, actor, producer, screenwriter, underwater cinematographer and stuntman.  He is best known for his underwater stunt work, playing the Gill-man in "Creature from the Black Lagoon", "Revenge of the Creature" and "The Creature Walks Among Us".  Other actors portrayed the creature on land.  He is also the only actor to have portrayed the creature more than once.  He is the only surviving Gill-man actor, and the last surviving original Universal Monster.

Creature from the Black Lagoon: Creature from the Black Lagoon is a 1954 American black-and-white 3D monster horror film from Universal-International, produced by William Alland, directed by Jack Arnold, that stars Richard Carlson, Julia Adams, Richard Denning, Antonio Moreno, and Whit Bissell.  The Creature was played by Ben Chapman on land and by Ricou Browning underwater.  The film premiered in Detroit on February 12 and was released on a regional basis, opening on various dates.

Rei Hiroe: Rei Hiroe (広江 礼威 , Hiroe Rei , born 5 December 1972) is a Japanese manga artist who is best known for his latest manga, "Black Lagoon".  When he is working on doujin comics he goes by the name Red Bear and TEX-MEX.  Hiroe's manga were originally published by Kadokawa Shoten in the 1990s but none were complete.  As a response Hiroe transferred to Shogakukan in the early 2000s, where all of his manga released before "Black Lagoon" were republished and re-released.

Gill-man: Gill-man—commonly called The Creature—is the lead antagonist of the 1954 black-and-white science fiction film "Creature from the Black Lagoon" and its two sequels "Revenge of the Creature" (1955) and "The Creature Walks Among Us" (1956).

Lagoon Boy: Lagoon Boy is a fictional superhero published by DC Comics.  His name and appearance are references to the title character from the classic horror feature film "The Creature from the Black Lagoon".

Eucritta: Eucritta melanolimnetes ("the true creature from the black lagoon") is an extinct stem-tetrapod of the extinct genus Eucritta from the Viséan epoch in the Carboniferous period of Scotland.  Its name is a homage to the 1954 sci-fi/horror movie "Creature from the Black Lagoon".

The Creature Walks Among Us: The Creature Walks Among Us, released in 1956, is the third and final installment of the "Creature from the Black Lagoon" horror film series from Universal Pictures, following 1955's "Revenge of the Creature".  The film was directed by John Sherwood, the long-time Universal-International assistant director, in his directorial debut.  Jack Arnold, who had directed the first two films in the series, had moved on to "A-list" films, and felt he had no more to contribute to the horror genre.  He suggested that his assistant director, Sherwood, could move up to full director, which partly affected Universal's decision to allow him to direct the film.  "The Creature Walks Among Us" starred Jeff Morrow, Rex Reason, and Leigh Snowden, and, like the original "Creature from the Black Lagoon", had music composed by Henry Mancini, who at the time was under contract with Universal.

Revenge of the Creature: Revenge of the Creature (also known as Return of the Creature and Return of the Creature from the Black Lagoon) is the first sequel to "Creature from the Black Lagoon", being the only 3-D film released in 1955 and the only 3-D sequel to a 3-D film released during "the golden age of 3-D".  Directed by Jack Arnold, the film stars John Agar and Lori Nelson.  This was Clint Eastwood's film debut.

Supporting paragraphs: Eucritta Creature from the Black Lagoon
Answer: is an extinct stem-tetrapod