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General characteristics of a large marine ecosystem (Gulf of Alaska). Marine life, sea life or ocean life is the collective ecological communities that encompass all aquatic animals, plants, algae, fungi, protists, single-celled microorganisms and associated viruses living in the saline water of marine habitats, either the sea water of marginal seas and oceans, or the brackish water of coastal ...
Osteichthyes (bone-fish) or bony fishes are a taxonomic group of fish that have bone, as opposed to cartilaginous skeletons. The vast majority of fish are osteichthyans, which is an extremely diverse and abundant group consisting of 45 orders, with over 435 families and 28,000 species. [21] It is the largest class of vertebrates in existence today.
An average of 2,332 new species per year are being described. [2] [3] Marine life is studied scientifically in both marine biology and in biological oceanography. By volume, oceans provide about 90% of the living space on Earth, [4] and served as the cradle of life and vital biotic sanctuaries throughout Earth's geological history.
The vertebrates include mammals, birds, amphibians, and various classes of fish and reptiles. The fish include the jawless Agnatha, and the jawed Gnathostomata. The jawed fish include both the cartilaginous fish and the bony fish. Bony fish include the lobe-finned fish, which gave rise to the tetrapods, the animals with four
Haikouichthys, a jawless fish, is popularized as one of the earliest fishes and probably a basal chordate or a basal craniate. [72] Ferns first appear in the fossil record about 360 million years ago in the late Devonian period. [73] Synapsids such as Dimetrodon were the largest terrestrial vertebrates in the Permian period, 299 to 251 million ...
Fish-eating birds of prey, such as sea eagles and ospreys, are also typically excluded, however tied to marine environments they may be. [6] Some birds, such as darters and anhingas, are primarily found in freshwater habitats, but may occasionally venture into marine or coastal areas as well; [7] [8] such birds are generally not considered to ...
Agnatha (/ ˈ æ ɡ n ə θ ə, æ ɡ ˈ n eɪ θ ə /; [3] from Ancient Greek ἀ-(a-) 'without' and γνάθος (gnáthos) 'jaws') is a paraphyletic infraphylum [4] of non-gnathostome vertebrates, or jawless fish, in the phylum Chordata, subphylum Vertebrata, consisting of both living (cyclostomes) and extinct (conodonts, anaspids, and ostracoderms, among others).
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.