Extant species in the context of "Dolphins"

A dolphin is a common name used for some of the aquatic mammals in the cetacean clade Odontoceti, the toothed whales. Dolphins belong to the families Delphinidae (the oceanic dolphins), along with the river dolphin families Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (the brackish dolphins), and probably extinct Lipotidae (baiji or Chinese river dolphin). There are 40 extant species named as dolphins.

Dolphins range in size from the 1.7-metre-long (5 ft 7 in) and 50-kilogram (110-pound) Maui's dolphin to the 9.5 m (31 ft) and 10-tonne (11-short-ton) orca. Various species of dolphins exhibit sexual dimorphism where the males are larger than females. They have streamlined bodies and two limbs that are modified into flippers. Though not quite as flexible as seals, they are faster; some dolphins can briefly travel at speeds of 29 kilometres per hour (18 mph) or leap about 9 metres (30 ft). Dolphins use their conical teeth to capture fast-moving prey. They have well-developed hearing which is adapted for both air and water; it is so well developed that some can survive even if they are blind. Some species are well adapted for diving to great depths. They have a layer of fat, or blubber, under the skin to keep warm in the cold water.

Bovines (subfamily Bovinae) comprise a diverse group of 10 genera of medium to large-sized ungulates, including cattle, bison, African buffalo, water buffalos, and the four-horned and spiral-horned antelopes. The members of this group of bovids are classified into loose tribes rather than formal subgroups, as the evolutionary relationships within the groups are still uncertain. General characteristics include cloven hooves and usually at least one of the sexes of a species having true horns. The largest extant bovine is the gaur.

In many countries, bovine milk and meat is used as food by humans. Cattle are kept as livestock almost everywhere except in parts of India and Nepal, where they are considered sacred by most Hindus. Bovines are used as draft animals and as riding animals. Small breeds of domestic bovine, such as the Miniature Zebu, are kept as pets. Bovine leather is durable and flexible and is used to produce a wide range of goods including clothing and bags.

The American alligator (Alligator mississippiensis), sometimes referred to as a common alligator or just gator, is a large crocodilian reptile native to the Southeastern United States. It is one of the two extant species in the genus Alligator, and is larger than the only other living alligator species, the Chinese alligator.

Adult male American alligators measure 3.4 to 4.5 m (11.2 to 14.8 ft) in length, and can weigh up to 500 kg (1,100 lb), with unverified sizes of up to 5.84 m (19.2 ft) and weights of 1,000 kg (2,200 lb) making it the second longest and the heaviest of the family Alligatoridae, after the black caiman. Females are smaller, measuring 2.6 to 3 m (8.5 to 9.8 ft) in length. The American alligator inhabits subtropical and tropical freshwater wetlands, such as marshes and cypress swamps, from southern Texas to North Carolina. It is distinguished from the sympatric American crocodile by its broader snout, with overlapping jaws and darker coloration, and is less tolerant of saltwater but more tolerant of cooler climates than the American crocodile, which is found only in tropical and warm subtropical climates.

Cyclothone is a genus containing 13 extant species of bioluminescent fish, commonly known as 'bristlemouths' or 'bristlefishes' due to their shared characteristic of sharp, bristle-like teeth. These fishes typically grow to around 1–3 inches (25–76 mm), though some can be larger. These deep-sea fish are most commonly found in the mesopelagic zone of the ocean, mostly at depths of over 300 meters (1,000 feet), and many species have bioluminescence.

Cyclothone is believed to be the most abundant fish genus on Earth, with estimates that there are up to a quadrillion individuals (10, or one million billion in the short scale) within the current global population. They are so abundant that they are also believed to be the most abundant genus of vertebrate on earth.

Sequoia is a genus of redwood coniferous trees in the subfamily Sequoioideae of the family Cupressaceae. The only extant species of the genus is Sequoia sempervirens in the Northern California coastal forests ecoregion of Northern California and Southwestern Oregon in the United States. The two other genera in the subfamily Sequoioideae, Sequoiadendron and Metasequoia, are closely related to Sequoia. It includes the tallest trees, as well as the heaviest, in the world.

Several extinct species have been named from fossils, including Sequoia affinis (Western North America) and Sequoia magnifica (petrified wood from the Yellowstone National Park area).

Sequoiadendron is a genus of evergreen trees, with three species, only one of which survives to the present:

• Sequoiadendron giganteum, extant, commonly known as wellingtonia, giant redwood and giant sequoia, growing naturally in the Sierra Nevada mountains of California
• † Sequoiadendron chaneyi, the predecessor of Sequoiadendron giganteum, found mostly in the Nevada area of the Tertiary Colorado Plateau until the late Miocene
• †Sequoiadendron tchucoticum Late Cretaceous; Enmyvaam River Basin, Russia