X-Ray Tetra
Xeme (Sabine’s Gull)
Xenacanthus
Xenoceratops
Xenoposeidon
Xenotarsosaurus
Xerus
Xiaosaurus
Xiaotingia
Xingu River Ray
Xiongguanlong
Xiphactinus
Xoloitzcuintli

Yabby
Yak
Yakutian Laika
Yarara
Yellow Anaconda
Yellow Aphids
Yellow Bass
Yellow Bellied Sapsucker
Yellow Belly Ball Python
Yellow Bullhead: Adaptable American Catfish
Yellow Cobra
Yellow Crazy Ant
Yellow Perch
Yellow Sac Spider
Yellow Spotted Lizard
Yellow Tanager (Black-and-Yellow Tanager)
Yellow Tang
Yellow-Bellied Sea Snake
Yellow-Eyed Penguin
Yellow-faced Bee
Yellowfin Tuna
Yellowhammer
Yellowish Cuckoo Bumblebee (formerly Fernald’s Cuckoo Bumblebee)
Yellowjacket (Yellow Jacket)
Yellowtail Snapper
Yellowthroat
Yeti Crab
Yokohama Chicken
Yoranian
Yorkie Bichon
Yorkiepoo
Yorkshire Terrier

Zebra
Zebra Finch
Zebra Mussels
Zebra Pleco
Zebra Shark
Zebra Snake
Zebra Spitting Cobra
Zebra Tarantula
Zebrafish
Zebu
Zokor
Zonkey
Zorse
Zuchon

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.

Caninae, whose members are known as canines (/keɪnaɪnz/),[6]: 182  is the only living subfamily within Canidae, alongside the extinct Borophaginae and Hesperocyoninae.[7][1] They first appeared in North America, during the Oligocene around 35 million years ago, subsequently spreading to Asia and elsewhere in the Old World at the end of the Miocene,[6]: 122  some 7 million to 8 million years ago.[7]

The sperm whale or cachalot[a] (Physeter macrocephalus) is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus Physeter  and one of three extant species in the sperm whale superfamily Physeteroidea, along with the pygmy sperm whale and dwarf sperm whale of the genus Kogia.

The humpback whale (Megaptera novaeangliae) is a species of baleen whale. It is a rorqual (a member of the family Balaenopteridae) and is the only species in the genus Megaptera. Adults range in length from 14–17 m (46–56 ft) and weigh up to 40 metric tons (44 short tons). The humpback has a distinctive body shape, with long pectoral fins and tubercles on its head. It is known for breaching and other distinctive surface behaviors, making it popular with whale watchers. Males produce a complex song that typically lasts from 4 to 33 minutes.

The orca (Orcinus orca), or killer whale, is a toothed whale and the largest member of the oceanic dolphin family. The only extant  species in the genus Orcinus, it is recognizable by its distinct pigmentation; being mostly black on top, white on the bottom and having recognizable white eye patches. A cosmopolitan species, it inhabits a wide range of marine environments, from Arctic to Antarctic regions to tropical seas, but is more commonly documented in temperate or cooler coastal waters. Scientists have proposed dividing the global population into races, subspecies, or possibly even species.

The North Atlantic right whale (Eubalaena glacialis) is a baleen whale, one of three right whale species belonging to the genus Eubalaena,[1] all of which were formerly classified as a single species. Because of their docile nature, their slow surface-skimming feeding behaviors, their tendencies to stay close to the coast, and their high blubber content (which makes them float when they are killed, and which produces high yields of whale oil), right whales were once a preferred target for whalers. At present, they are among the most endangered whales in the world,[6] and they are protected under the U.S. Endangered Species Act and Marine Mammal Protection Act and Canada's Species at Risk Act. There are an estimated 356[7] individuals in existence in the western North Atlantic Ocean—they migrate between feeding grounds in the Labrador Sea and their winter calving areas off Georgia and Florida, an ocean area with heavy shipping traffic. In the eastern North Atlantic, on the other hand—with a total population reaching into the low teens at most—scientists believe that they may already be functionally extinct.[6][dubious – discuss] Vessel strikes and entanglement in fixed fishing gear, which together account for nearly half of all North Atlantic right whale mortality since 1970,[8] are their two greatest threats to recovery.[9][10]

The Amazon river dolphin (Inia geoffrensis), also known as the boto, bufeo or pink river dolphin, is a species of toothed whale endemic to South America and is classified in the family Iniidae. Three subspecies are currently recognized: I. g. geoffrensis (Amazon river dolphin), I. g. boliviensis (Bolivian river dolphin) and I. g. humboldtiana (Orinoco river dolphin). The position of the Araguaian river dolphin (I. araguaiaensis) within the clade is still unclear.[3][4] The three subspecies are distributed in the Amazon basin, the upper Madeira River in Bolivia, and the Orinoco basin, respectively.