Wood cutting print.Artist Robert Kretschmer.Wood cutting by R. Illner.From Брем, Альфред Эдмунд (Alfred Edmund Brehm), Жизнь животных, Т. 3, Пресмыкающиеся, земноводные, рыбы, насекомые, низшие животные, Санкт-Петербург, «Просвещение», 1902.Alfred Edmund Brehm (German, born 2 February 1829 in Unterrenthendorf, now called Renthendorf; died 11 November 1884 in Renthendorf) was a German zoologist, natural history illustrator and writer, the son of Christian Ludwig Brehm.Robert Kretschmer (1812-1872) was a German illustrator, known for his illustrations in Brehms Tierleben.Corals are marine invertebrates in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton. A coral "head" is a colony of myriad genetically identical polyps. Each polyp is a spineless animal typically only a few millimeters in diameter and a few centimeters in length. A set of tentacles surround a central mouth opening. An exoskeleton is excreted near the base. Over many generations, the colony thus creates a large skeleton that is characteristic of the species. Individual heads grow by asexual reproduction of polyps. Corals also breed sexually by spawning: polyps of the same species release gametes simultaneously over a period of one to several nights around a full moon. Although some corals can catch small fish and plankton, using stinging cells on their tentacles, like those in sea anemone and jellyfish, most corals obtain the majority of their energy and nutrients from photosynthetic unicellular algae that live within the coral's tissue called zooxanthella (also known as Symbiodinium). Such corals require sunlight and grow in clear, shallow water, typically at depths shallower than 60 metres (200 ft). Corals can be major contributors to the physical structure of the coral reefs that develop in tropical and subtropical waters, such as the enormous Great Barrier Reef off the coast of Queensland, Australia. Other corals do not have associated algae and can live in much deeper water, with the cold-water genus Lophelia surviving as deep as 3,000 metres (9,800 ft). Examples live on the Darwin Mounds, north-west of Cape Wrath, Scotland. Corals have also been found off the coast of the U.S. in Washington State and the Aleutian Islands in Alaska.Approx. image size 19, 7 x 12, 6/24, 8 x 17 cm.

Condition: medium.