Cetacean glossary

The vocabulary of cetology: the study of cetaceans, borrows from anatomy, ethology, acoustics and marine ecology. This glossary brings together the most common terms, explained simply, to help you make better sense of scientific papers, field guides and our species profiles.

Click on a letter to go straight to the matching section: A · B · C · D · E · F · G · H · I · L · M · N · O · P · R · S · T · U · V · Z

A

Allocare: Behaviour in which females in a group look after the young of another female (guarding, protection, escorting to the surface while the mother dives). Very well documented in sperm whales and in some delphinids.

Apnoea (breath-hold): The ability to hold the breath underwater. In cetaceans it is made possible by a high concentration of muscle myoglobin, a bradycardia reflex and a redistribution of blood towards the vital organs.

B

Baleine (whale): In the strict sense, the French term designates the baleen whales (mysticetes). In everyday usage it is also applied to large cetaceans in general, which can cause confusion (the sperm whale, for example, is not a baleine in the scientific sense).

Whaler: A ship built for whaling. Commercial whaling has been banned since the IWC moratorium of 1986, but a few countries (Norway, Iceland, Japan, the Faroe Islands) still practise it.

Blow: See “blow (spout)”.

Breaching: A spectacular leap by a cetacean clear of the water, followed by a fall back. Particularly frequent in the humpback whale. Its function is still debated: communication, social signalling, dislodging of parasites, sheer exuberance.

Buzz: A rapid burst of echolocation clicks emitted by an odontocete just before it takes prey, marking the terminal phase of the approach.

By-catch: Accidental capture of cetaceans (or of other non-target species) in fishing gear. The leading cause of human-induced mortality in many species.

C

Sperm whale: An odontocete cetacean of the family Physeteridae. Physeter macrocephalus is the largest of the toothed whales and the deepest diver. See our full profile.

Cetaceans: An order of marine mammals (Cetacea) comprising the mysticetes (baleen whales) and the odontocetes (toothed whales). About 90 living species.

Cetology: The science that studies cetaceans. An interdisciplinary field combining biology, ecology, acoustics, genetics and ethology.

Clan: In the sperm whale, a set of several social units sharing the same coda dialect. A clan may bring together several thousand individuals across an ocean basin.

Click: A brief, impulsive sound emitted by odontocetes, mainly for echolocation but also for communication.

Coda: A rhythmic sequence of clicks produced by sperm whales, specific to social communication and structured by dialect. Regarded by some researchers as a proto-language.

D

Delphinidae: A family of odontocete cetaceans bringing together most dolphin species: common bottlenose dolphin, killer whale, pilot whale, Risso’s dolphin and others.

Dialect: A local variant of acoustic signals particular to a clan or a population. Documented in the sperm whale, the killer whale and several delphinids.

Dorsal fin: The fin on the back. Its shape, its height and its position are major criteria for visual identification.

E

Stranding: A case in which a cetacean comes ashore alive or dead. Mass strandings puzzle scientists and may be linked to health-related, geomagnetic, acoustic or behavioural factors. See our feature on strandings.

Echolocation: A biological system for locating objects by emitting sounds and analysing the echoes. Used by all odontocetes to orient themselves and to hunt in darkness or in turbid water.

target Phonic lips Melon (acoustic lens) clicks emitted → ← echo

Blowhole: The nostril on top of the skull through which a cetacean breathes. Mysticetes have two, odontocetes a single one.

water surface V-shaped blow 2 blowholes (mysticete)

F

Baleen plate: A keratinous plate attached to the upper jaw of mysticetes, used to filter food by retaining krill or small fish. See our dedicated page.

⋯ ⋯ Upper jaw Lower jaw Baleen (keratin plates that filter krill)

Fluking: The action by which a cetacean raises its tail fluke clear of the water as it starts a deep dive. Characteristic of humpback whales and of the sperm whale.

G

Pilot whale: A medium-sized odontocete cetacean with a bulbous head, living in large social groups. Two main species: the long-finned pilot whale (Globicephala melas) and the short-finned pilot whale (G. macrorhynchus).

H

Pelagic habitat: Open-sea habitat, away from the coast, generally over great depths. It is the preferred habitat of the sperm whale, Cuvier’s beaked whale and Risso’s dolphin.

I

IUCN / UICN: International Union for Conservation of Nature. It draws up the “Red List” of threatened species, with statuses running from “Least Concern” (LC) to “Extinct” (EX).

L

Phonic lips: Muscular structures in the nose of odontocetes, which produce the echolocation clicks. The sound is then focused by the melon.

Lobtailing: Behaviour consisting of striking the surface of the water with the tail fluke. Observed in several cetaceans, in particular the humpback whale.

M

Porpoise: A small odontocete cetacean of the family Phocoenidae, distinct from the dolphins by a short rostrum, a triangular dorsal fin and inconspicuous behaviour.

Melon: A fatty organ in the forehead of odontocetes, used to focus the sounds emitted during echolocation and communication.

Blowhole MELON phonic lips bony skull rostrum

Mysticete: The suborder of baleen whales. It includes the rorquals, the humpback whale, the blue whale, the grey whale, the right whales and others.

N

External nostril: See “blowhole”.

Narwhal: An Arctic cetacean famous for the long spiral tusk of the males (in fact an upper left tooth). Belongs to the family Monodontidae.

O

Odontocete: The suborder of toothed whales. It includes the sperm whales, dolphins, killer whales, porpoises, belugas, narwhals, beaked whales and others.

Killer whale: The largest of the dolphins (Orcinus orca). A social, intelligent cetacean and a predator of high trophic level, present in every ocean.

P

Pelagos (sanctuary): An international marine protected area in the north-western Mediterranean (France, Italy, Monaco), created in 1999 to protect marine mammals.

Photo-identification: A method of identifying individual cetaceans from unique markings (scars, tail patterns, dorsal fin profile). It allows populations to be monitored without capture.

Free-diving: See “apnoea (breath-hold)”.

Tail-stand: Behaviour in which the animal holds its tail stock vertically out of the water, over 1 to 2 metres, staying that way for a few seconds. Typical of Risso’s dolphin.

R

Rete mirabile: “Wonderful net”: a complex vascular structure allowing thermal regulation and the redistribution of blood in diving cetaceans.

Artery, warm blood entering (36°C) Vein, cold blood returning (5°C) heat exchange

RNE: Réseau National Échouage, the French stranding network coordinated by the Observatoire Pelagis (CNRS, La Rochelle), which centralises and studies strandings of marine mammals.

Rorqual: A mysticete of the family Balaenopteridae, characterised by extensible throat pleats that allow it to engulf large volumes of water. Fin whale, common minke whale, sei whale, blue whale, humpback whale.

Rostrum: The elongated front part of the jaw in many odontocetes (dolphins, porpoises). Absent in Risso’s dolphin and in the sperm whale.

S

Throat pleats: Longitudinal folds beneath the throat of rorquals, which stretch considerably when prey and water are engulfed.

Throat pleats (accordion-like, extensible) Rorqual / humpback whale

Sonar (biological): See “echolocation”.

Blow (spout): The visible exhalation of a cetacean at the surface, made of water vapour and mucus. Its shape and its height are characteristic of the species.

Spermaceti: A fatty organ in the head of the sperm whale, filled with a clear oil (once prized by industry). It plays a part in echolocation and possibly in buoyancy.

Spy-hopping: Raising the head vertically above the surface, often to take in the surroundings above water. Observed in the killer whale, Risso’s dolphin and the grey whale.

T

Teuthophagous: Feeding mainly on cephalopods (squid, cuttlefish). Characterises in particular the sperm whale, Cuvier’s beaked whale and Risso’s dolphin.

Trophic level: The position of an organism in the food chain. Predatory cetaceans (killer whale, sperm whale) occupy the highest levels.

U

Social unit: A stable group of cetaceans linked by lasting social bonds. In the sperm whale these units are matrilineal.

V

Vibrissal hair: Sensory hairs present in newborn cetaceans, which generally disappear in adulthood (a terrestrial remnant).

Z

Ziphiid: A family of odontocete cetaceans bringing together the beaked whales, among them Cuvier’s beaked whale (Ziphius cavirostris). Characterised by a prominent melon and deep diving. See our profile.

Carry on exploring