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Evolution of fish. The Devonian period (419–359 Mya), also known as the Age of Fishes, saw the development of early sharks, armoured placoderms and various lobe-finned fish, including the tetrapod transitional species. The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early ...
By the Upper Devonian period, the fin-limb transition as well as other skeletal changes such as gill arch reduction, opercular series loss, mid-line fin loss, and scale reduction were already completed in many aquatic organisms. [ 3] As aquatic tetrapods began their transition to land, several skeletal changes are thought to have occurred to ...
A gill (/ ɡɪl / ⓘ) is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are kept moist. The microscopic structure of a gill presents a large surface area to the ...
Adaptation is the evolutionary process whereby an organism becomes better able to live in its habitat or habitats. [25][26][27] 2. Adaptedness is the state of being adapted: the degree to which an organism is able to live and reproduce in a given set of habitats. [28]
Chimaeras differ from other cartilagenous fish, having lost both the spiracle and the fifth gill slit. The remaining slits are covered by an operculum, developed from the septum of the gill arch in front of the first gill. [6] The shared trait of breathing via gills in bony fish and cartilaginous fish is a famous example of symplesiomorphy.
Fish have evolved sophisticated ways of using colouration. For example, prey fish have ways of using colouration to make it more difficult for visual predators to see them. In pelagic fish, these adaptations are mainly concerned with a reduction in silhouette, a form of camouflage. One method of achieving this is to reduce the area of their ...
Psarolepis. Achoania. Actinopterygii (ray-finned fish) Sarcopterygii (lobe-finned fish, including tetrapods) Osteichthyes (/ ˌɒstiːˈɪkθi.iːz /), also known as osteichthyans or commonly referred to as the bony fish, is a diverse superclass of vertebrate animals that have endoskeletons primarily composed of bone tissue.
A macrophyte is a plant that grows in or near water and is either emergent, submergent, or floating. In lakes and rivers, macrophytes provide cover for fish, substrate for aquatic invertebrates, produce oxygen, and act as food for some fish and wildlife. [1] Macrophytes are primary producers and are the basis of the food web for many organisms. [2]