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The term "fish" describes any non-tetrapod chordate, (i.e., an animal with a backbone), that has gills throughout life and has limbs, if any, in the shape of fins. [8] Unlike groupings such as birds or mammals, fish are paraphyletic, since the tetrapod clade is within the clade of lobe-finned fishes. [9] [10]
The diets of marine mammals vary considerably as well; some eat zooplankton, others eat fish, squid, shellfish, or seagrass, and a few eat other mammals. While the number of marine mammals is small compared to those found on land, their roles in various ecosystems are large, especially concerning the maintenance of marine ecosystems, through ...
The giant oarfish is by far the largest member of the family, at a length of 8 m (26 ft)—with unconfirmed reports of specimens 11 m (36 ft) and 17 m (56 ft) [3] [9] [10] in length and 270 kg (600 lb) in weight. [11] The streamer fish reaches 3 m (9.8 ft) in length, [12] while the largest recorded specimen of Regalecus russelii was 5.4 m (18 ft).
Their diet varies considerably as well: some may eat zooplankton; others may eat fish, squid, shellfish, and sea-grass; and a few may eat other mammals. In a process of convergent evolution , marine mammals such as dolphins and whales redeveloped their body plan to parallel the streamlined fusiform body plan of pelagic fish .
A fish (pl.: fish or fishes) is an aquatic, anamniotic, gill-bearing vertebrate animal with swimming fins and a hard skull, but lacking limbs with digits.Fish can be grouped into the more basal jawless fish and the more common jawed fish, the latter including all living cartilaginous and bony fish, as well as the extinct placoderms and acanthodians.
In 1997, the classification of mammals was revised by Malcolm C. McKenna and Susan K. Bell. [10] The Classification of Mammals Above the species level, here referred to as the "McKenna/Bell classification", is a comprehensive work on the systematics, relationships, and occurrences of all mammal taxa, living and extinct, down through the rank of ...
Many members of the fish family Poeciliidae are considered to be lecithotrophic, however, research is increasingly showing that others are matrotrophic. [11] "Aplacental viviparity" occurs when the female retains the embryos during the entire time of development but without any transfer of nutrients to the young.
Craniata also includes all lampreys and armoured jawless fishes, armoured jawed fish, sharks, skates, and rays, and teleostomians: spiny sharks, bony fish, lissamphibians, temnospondyls and protoreptiles, sauropsids and mammals. The craniate head consists of a three-part brain, neural crest which gives rise to many cell lineages, and a cranium ...