IWC is a voluntary international organization and is not backed up by treaty, therefore, the IWC has substantial practical limitations on its authority. First, any member countries are free to simply leave the organization and declare themselves not bound by it if they so wish. Second, any member state may opt out of any specific IWC regulation by lodging a formal objection to it within 90 days of the regulation coming into force (such provisions are common in international agreements, on the logic that it is preferable to have parties remain within the agreements than opt out altogether). Third, the IWC has no ability to enforce any of its decisions through penalty imposition.

Cetaceans, (order Cetacea), include any member of an entirely aquatic group of mammals commonly known as whales, dolphins, and porpoises. There is though a distinction between toothed (Odontoceti) and baleen whales like the blue and humpback (filter feeders), where dolphins and sperm whales have teeth.

The ancient Greeks recognized that cetaceans breathe air, give birth to live young, produce milk, and have hair - all features of mammals. Because of their body form, however, cetaceans were commonly grouped with the fishes. Cetaceans are entirely carnivorous, although members of the order Sirenia (manatees, dugongs, and Steller’s sea cow) were once referred to as the “herbivorous Cetacea.”

In the past cetaceans were important resources, but by the end of the 20th century their economic importance was almost solely due to whale watching, a tourist activity and major source of income for certain coastal regions of many countries.

Most species prefer the colder waters of the Northern and Southern Hemispheres. They spend their lives in the water of seas and rivers; having to mate, give birth, molt or escape from predators, like killer whales, underwater. This has been enabled by unique evolutionary adaptations in their physiology and anatomy. They feed largely on fish and marine invertebrates; but a few, like the killer whale, feed on large mammals and birds, such as penguins and seals. Some baleen whales (mainly gray whales and right whales) are specialised for feeding on benthic creatures. Male cetaceans typically mate with more than one female (polygyny), although the degree of polygyny varies with the species.

Cetaceans are not known to have pair bonds. Male cetacean strategies for reproductive success vary between herding females, defending potential mates from other males, or whale song which attracts mates. Calves are typically born in the fall and winter months, and females bear almost all the responsibility for raising them. Mothers of some species fast and nurse their young for a relatively short period of time, which is more typical of baleen whales as their main food source (invertebrates) aren't found in their breeding and calving grounds (tropics). Cetaceans produce a number of vocalizations, notably the clicks and whistles of dolphins and the moaning songs of the humpback whale.

The meat, blubber and oil of cetaceans have traditionally been used by indigenous peoples of the Arctic. Cetaceans have been depicted in various cultures worldwide. Dolphins are commonly kept in captivity and are even sometimes trained to perform tricks and tasks, other cetaceans aren't as often kept in captivity (with usually unsuccessful attempts). Cetaceans have been extensively hunted by commercial industries for their products, although hunting the largest whales is now forbidden by international law.

The baiji (Chinese river dolphin) has become "Possibly Extinct" in the past century, while the vaquita and Yangtze finless porpoise are ranked Critically Endangered by the International Union for Conservation of Nature. Besides hunting, cetaceans also face threats from accidental trapping and environmental hazards such as marine pollution, noise pollution and ongoing climate change.

Cetacean bodies are generally similar to that of fish, which can be attributed to their lifestyle and the habitat conditions. Their body is well-adapted to their habitat, although they share essential characteristics with other higher mammals (Eutheria).

They have a streamlined shape, and their forelimbs are flippers. Almost all have a dorsal fin on their backs that can take on many forms depending on the species. A few species, such as the beluga whale, lack them. Both the flipper and the fin are for stabilization and steering in the water.

The male genitals and mammary glands of females are sunken into the body.

The body is wrapped in a thick layer of fat, known as blubber, used for thermal insulation and gives cetaceans their smooth, streamlined body shape. In larger species, it can reach a thickness up to half a meter (1.6 ft).

Sexual dimorphism evolved in many toothed whales. Sperm whales, narwhals, many members of the beaked whale family, several species of the porpoise family, killer whales, pilot whales, eastern spinner dolphins and northern right whale dolphins show this characteristic. Males in these species developed external features absent in females that are advantageous in combat or display. For example, male sperm whales are up to 63% percent larger than females, and many beaked whales possess tusks used in competition among males. Hind legs are not present in cetaceans, nor are any other external body attachments such as a pinna and hair.

Cetaceans are found in many aquatic habitats. While many marine species, such as the blue whale, the humpback whale and the killer whale, have a distribution area that includes nearly the entire ocean, some species occur only locally or in broken populations. These include the vaquita, which inhabits a small part of the Gulf of California and Hector's dolphin, which lives in some coastal waters in New Zealand. River dolphin species live exclusively in fresh water.

Many species inhabit specific latitudes, often in tropical or subtropical waters, such as Bryde's whale or Risso's dolphin. Others are found only in a specific body of water. The southern right whale dolphin and the hourglass dolphin live only in the Southern Ocean. The narwhal and the beluga live only in the Arctic Ocean. Sowerby's beaked whale and the Clymene dolphin exist only in the Atlantic and the Pacific white-sided dolphin and the northern straight dolphin live only in the North Pacific.

Cosmopolitan species may be found in the Pacific, Atlantic and Indian Oceans. However, northern and southern populations become genetically separated over time. In some species, this separation leads eventually to a divergence of the species, such as produced the southern right whale, North Pacific right whale and North Atlantic right whale. Migratory species' reproductive sites often lie in the tropics and their feeding grounds in polar regions.

Thirty-two species are found in European waters, including twenty-five toothed and seven baleen species.

The two primary suborders include the Odontoceti suborder (toothed whales) which includes all species of dolphin and porpoise along with whales such as the sperm whale, killer whale (Delphinidae), beluga whale and narwhal whale, and the Mysticeti suborder (baleen whales) which includes the humpback whale, bowhead whale, blue whale and minke whale among other large (toothless) whales.

All species regardless of their suborder share several physical characteristics with those who belong to the cetacean family.

They all have flippers designed for swimming, a tail with flukes used for navigating the water and nasal openings (blowholes) for breathing.

Because all cetaceans are marine mammals they are warm-blooded, breathe air, produce milk and bear offspring, which is common among all land and marine based mammals.

Whales are considered one of the most intelligent animals on earth.

Kulo Luna - Fictional cetacean based on Mocha Dick (The $Billion Dollar Whale)

Moby Dick - Fictional cetacean based on Mocha Dick, a real giant white sperm whale

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