List of Cetaceans - Meaning, Types And Characteristics

So what is the exact definition of cetaceans? The order Cetacea is made up of two suborders: Mysticeti , formed by the baleen whales, and Odontoceti, composed of cetaceans with teeth, such as sperm whales, dolphins and killer whales.

The evolutionary histories of both suborders are incredibly similar, as their shared characteristics reflect adaptations to life in the water. Although both groups share a cetacean ancestor, traits such as body shape, nasal fossa, blowhole positioning, lung shape and lack of vocal cords have helped them thrive in aquatic environments.

Cetaceans are mammals that breathe with lungs and inhabit our seas and oceans, although some species also live in rivers. Because they breathe air, they must come to the surface regularly, even when they spend much of their lives underwater.

For more, we suggest taking a look at our aquatic mammals list.

Cetacean animals are characterized by their anatomy, morphology, physiology and habitat. The main characteristics of cetaceans are:

• They exhibit an exceptionally wide range of body sizes, and their physiology affects how much oxygen they can store and use during dives. These adaptations help reduce the risk of hypoxia, or a lack of oxygen in body tissues.
• When diving and swimming, their hearts direct blood to the brain, lungs and muscles to allow for continuous body functioning.
• Cetacean tracheas are shorter than those of terrestrial mammals and are not linked to the esophagus. The trachea connects to the blowhole, where they inhale and exhale.
• They have large fat reservoirs, called blubber, to prevent hypothermia, specifically when submerging to greater depths. Blubber also provides an energy reserve.
• The hydrodynamic shape of their bodies reduces drag and allows for greater swimming speed, while other adaptations help them withstand pressure changes at depth.
• They lack vocal cords. Instead, toothed cetaceans have an organ called the melon which they use to communicate or hunt by echolocation.
• They have incredibly thick skin. The outermost layer, the epidermis, is constantly renewed.
• At birth, young cetaceans have hair, which disappears within a few months of life.
• The number of fins depends on the species, although all have pectoral and caudal fins.
• Some species have teeth of the same size and shape. Others have baleen plates, which they use to filter food from the water.

For more cetacean facts and examples, keep reading below.

As we’ve already mentioned, cetaceans are marine mammals that live in rivers and oceans around the world. Some cetaceans live in circumpolar waters, such as the beluga whale (Delphinapterus leucas) or the narwhal (Monodon monoceros), and they have adapted to these low temperatures. Others, such as the long-finned pilot whale (Globicephala melas) and the short-finned pilot whale (Globicephala macrorhynchus), live in warmer tropical waters.

Some of the most endangered cetaceans live in fresh water. The decline in these populations is a result of river pollution, dam construction and indiscriminate hunting. One of the most commonly asked questions is, ‘‘Can dolphins live in fresh water?’’ Yes, some can. In fact, the most common freshwater cetaceans include:

• Bolivian river dolphin (Inia boliviensis)
• Araguaian river dolphin (Inia araguaiaensis)
• Amazon river dolphin (Inia geoffrensis)
• La Plata dolphin (Pontoporia blainvillei)
• Baiji (Lipotes vexillifer)
• South Asian river dolphin (Platanista minor)
• Ganges river dolphin (Platanista gangética)

These species are adapted to river habitats, where changing water levels and currents can affect where they find food and shelter. The vast majority of cetaceans migrate annually from their feeding areas to their breeding areas, and it is during this time that these animals are the most protected. Migration routes and timing vary between species and can be influenced by the availability of food.

Image below: amazon river dolphin

Cetaceans are classified into two large groups: Mysticeti and Odontoceti. Keep reading to discover our list of cetaceans:

Mysticeti, commonly referred to as baleen whales, are characterized by having filter-feeding baleen plates instead of teeth. These mammals are incredibly large and usually live in cold waters. Some species on this list haven’t been sighted in decades. Baleen plates hang from the upper jaw and help trap small prey as water passes through them. The most common Mysticeti baleen whale species include:

• North Pacific right whale (Eubalaena japonica)
• Bowhead whale (Balaena mysticetus)
• Fin whale (Balaenoptera physalus)
• The blue whale (Balaenoptera musculus)
• The humpback whale (Megaptera novaeangliae)
• Gray whale (Eschrichtius robustus)
• Pygmy right whale (Caperea marginata)

Image: fin whale

The Odontoceti, or toothed whales, are cetaceans with teeth. There are many toothed whale species, which vary widely. All odontocetes are carnivorous, and the most common Odontoceti include:

• Long-finned pilot whale (Globicephala melas)
• Peale’s dolphin (Lagenorhynchus australis)
• Killer whale (Orcinus orca)
• Striped dolphin (Stenella coeruleoalba)
• Common bottlenose dolphin (Tursiops truncatus)
• Atlantic white-sided dolphin (Lagenorhynchus acutus)
• Dusky dolphin (Lagenorhynchus obscurus)
• The harbour porpoise (Phocoena phocoena)
• Vaquita (Phocoena sinus)
• The spectacled porpoise (Phocoena dioptrica)
• Sperm whale (Physeter macrocephalus)
• Pygmy sperm whale (Kogia breviceps)
• Dwarf sperm whale (Kogia sima)
• Blainville’s beaked whale (Mesoplodon densirostris)
• Gervais’ beaked whale (Mesoplodon europaeus)
• Gray’s beaked whale (Mesoplodon grayi)

Many toothed whales use echolocation to locate prey and navigate, sending out sounds and interpreting the returning echoes. Their diets vary by species and may include fish, squid or other marine animals.

For more, we recommend reading about the marine animals in danger of extinction.

Image: Long-finned pilot whale

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