An aquatic ecosystem is an ecosystem found in and around a body of water, in contrast to land-based terrestrial ecosystems. Aquatic ecosystems contain communities of organisms—aquatic life—that are dependent on each other and on their environment. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems. Freshwater ecosystems may be lentic (slow moving water, including pools, ponds, and lakes); lotic (faster moving water, for example streams and rivers); and wetlands (areas where the soil is saturated or inundated for at least part of the time).
>>>PUT SHARE BUTTONS HERE<<<
👉 Aquatic environment in the context of Anamniotes
The anamniotes are an informal group of vertebrates comprising all fish and amphibians, which lay their eggs in aquatic environments. They are distinguished from the amniotes (reptiles, birds and mammals), which can reproduce on dry land either by laying shelled eggs or by carrying fertilized eggs within the female. Older sources, particularly before the 20th century, may refer to anamniotes as "lower vertebrates" and amniotes as "higher vertebrates", based on the antiquated idea of the evolutionary great chain of being.
The name "anamniote" is a back-formation word created by adding the prefix an- to the word amniote, which in turn refers to the amnion, an extraembryonic membrane present during the amniotes' embryonic development which serves as a biochemical barrier that shields the embryo from environmental fluctuations by regulating the oxygen, carbon dioxide and metabolic waste exchanges and secreting a cushioning fluid. As the name suggests, anamniote embryos lack an amnion during embryonic development, and therefore rely on the presence of external water to provide oxygen and help dilute and excrete waste products (particularly ammonia) via diffusion in order for the embryo to complete development without being intoxicated by their own metabolites. This means anamniotes are almost always dependent on an aqueous (or at least very moist) environment for reproduction and are thus restricted to spawning in or near water bodies. They are also highly sensitive to chemical and temperature variation in the surrounding water, and are also more vulnerable to egg predation and parasitism.
In this Dossier
Aquatic environment in the context of Semi-aquatic
In biology, being semiaquatic refers to various macro-organisms 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 (in which case they can also be called amphibious), or land animals that have spent at least one life stage (e.g. as eggs or larvae) 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.
Examples of semiaquatic animals and plants are given below.