The platypus, sometimes referred to as the duck-billed platypus, is a semiaquatic, egg-laying mammal endemic to eastern Australia, including Tasmania. The platypus is the sole living representative or monotypic taxon of its family Ornithorhynchidae and genus Ornithorhynchus, though a number of related species appear in the fossil record.
Platypus
A book for children published in Germany in 1798
Illustration from the first scientific description in 1799
Colour print from 1863
In biology, being semiaquatic refers to various macroorganisms that live regularly in both aquatic and terrestrial environments. When referring to animals, the term describes those that actively spend part of their daily time in water, or land animals that have spent at least one life stages in aquatic environments. When referring to plants, the term describes land plants whose roots have adapted well to tolerate regular, prolonged submersion in water, as well as emergent and (occasionally) floating-leaved aquatic plants that are only partially immersed in water.
The common frog, one of the most ubiquitous semiaquatic amphibians in Europe
Atlantic mudskippers, amphibious fish of mangrove swamps and tidal flats
Pachygrapsus marmoratus, a semiterrestrial crab
Hunting stance of Dolomedes minor, a semiaquatic spider