blowholeThe nostril a dolphin comes up to breathe through. Over time it moved from the snout to the crown of the head. The dolphin blows stale air out through it and takes fresh air in.
blubberThe thick coat of fat under a sea mammal's skin. Blubber holds in body heat in cold water. It also helps a dolphin float and stores energy.
calfA young dolphin, usually born tail first. A mother bottlenose dolphin nurses her calf for about 20 months, and the calf stays with her for 3 to 6 years.
cetaceanAny member of the whale, dolphin and porpoise group. The name comes from the Greek ketos, a large sea creature. There are about 90 kinds of cetacean.
dolphinA quick, beaked sea mammal closely related to whales. About 40 kinds are alive today. The smallest are about as long as a person is tall, and the largest is the orca.
dorsal finThe single upright fin halfway along the back. It steadies the dolphin and keeps it from rolling over as it swims. Blood vessels in the fin help the animal shed extra heat.
Show all 36 terms (30 more)
Dolphin basics, continued
echolocationSensing the surroundings by sound and its echoes. A dolphin sends out clicks and listens for them to bounce back. Hearing matters so much to dolphins that some can get by even if they are blind.
flipperA dolphin's broad, flat forelimb, used for steering. Flippers took the place of front legs. A dolphin has two, and no back limbs at all.
flukeEither of the two flat lobes of a dolphin's tail. The flukes lie flat, like a paddle. A dolphin swims by beating them up and down.
mammalAn air-breathing animal that nurses its young. Dolphins are mammals, though they look like fish. A newborn even has a row of hairs along each side of its snout.
podA social group of dolphins, often a dozen or fewer. Where food is plentiful, pods can join into a superpod of more than 1,000 dolphins. Dolphins come and go between pods.
porpoiseA small, stout cousin of the dolphin with no beak. Porpoises are among the smallest of the toothed whales. The smallest of them, the vaquita, is about 1.4 meters (4 feet 7 inches) long.
Body and behavior 12
bait ballSmall fish packed into a tight, swirling ball. Fish bunch up this way when hunters close in. A pod of dolphins will herd a school into a bait ball, then take turns swimming through it to feed.
bow ridingSurfing the wave pushed along by a boat's front. Riding the wave saves the dolphin energy. Dolphins may keep it up from a few minutes to several hours.
carnivoreOne that eats meat rather than plants. Dolphins are carnivores. Most eat fish and squid, and the biggest also hunt seals.
countershadingTwo-tone coloring: darker above, lighter below. Many dolphins are dark gray on the back and light on the belly. It is a kind of camouflage, shared with many fish, birds and other mammals.
gestationThe time a baby grows inside its mother. For a bottlenose dolphin it lasts about 12 months, and for an orca 15 to 18.
melonThe fatty bulge that rounds out a dolphin's forehead. The melon works like a lens for sound. It focuses the clicks a dolphin makes.
porpoisingMaking long, low leaps while swimming at speed. At high speed, leaping takes less energy than swimming, because air drags less than water. Penguins and seals do it too.
preyAn animal caught and eaten by a hunter. A dolphin's cone-shaped teeth are made for catching fast prey such as fish, squid and shrimp.
rostrumThe long, beak-like snout of a dolphin. Rostrum is the Latin word for beak. The bottlenose dolphin takes its name from its rostrum.
streamlinedSmooth and tapered, so water slides past easily. A dolphin's smooth, hairless, fish-shaped body is streamlined. Some dolphins can swim 29 kilometers (18 miles) an hour for a short time.
unihemispheric sleepSleep in which half the brain stays awake. The awake half lets a sleeping dolphin keep breathing and watch for danger. One eye is shut and the other stays open.
warm-bloodedAble to keep the body warmer than its surroundings. Mammals and birds are warm-blooded. Scientists now prefer more exact words, because animals control their heat in more than two ways.
Dolphin kinds and their world 12
bottlenose dolphinThe best-known dolphin, gray with a short beak. It grows 6 to 13 feet (2 to 4 meters) long and can live 40 to 60 years. It lives in warm and mild seas around the world.
bycatchCreatures that fishing gear traps by mistake. Dolphins, whales, sea turtles and seabirds can all be hooked or tangled in gear set for fish.
common dolphinThe most numerous dolphin, marked with an hourglass. There are thought to be about six million of them, more than any other cetacean.
conservationLooking after nature so that wild species survive. One dolphin shows why it matters: the baiji, the river dolphin of China's Yangtze, is probably extinct.
habitatWhere in nature a creature makes its home. Most dolphins live in warm tropical seas. A few kinds prefer cold water, and a few live in rivers.
marine biologistA scientist whose subject is life in the ocean. Biologists can tell one wild dolphin from another by the nicks and scars on its dorsal fin.
marine mammalA mammal that depends on the sea to live. Seals, sea otters, manatees and polar bears are marine mammals too. Only the whales, dolphins and porpoises and the manatees and dugongs never leave the water.
orcaA huge dolphin with a white patch near each eye. It is the largest dolphin of all and is also called the killer whale. An orca can be 32 feet (almost 10 meters) long and weigh as much as 11 tons.
river dolphinA dolphin that lives in fresh or brackish water. River dolphins live in South America and Asia. Their eyes are very small, and in muddy water they find their way by echolocation.
speciesOne kind of living thing, set apart from all others. A species is often defined as a group whose members can breed with one another and have young that can breed too.
spinner dolphinA small dolphin that spins as it leaps into the air. One leap can hold several full spins. Spinner dolphins rest in shallow coastal water in the morning and hunt offshore at night.
toothed whaleA whale that has teeth instead of baleen. Dolphins, porpoises and sperm whales are toothed whales. They breathe through one blowhole; baleen whales have two.
How this list was compiled: Term list chosen for this site on 2026-10-12. Each meaning is written in our own words and was checked that day against the article on the term in the English Wikipedia (https://en.wikipedia.org/), whose text is under the Creative Commons Attribution-ShareAlike license: Dolphin, Mammal, Cetacean, Porpoise, Blowhole (anatomy), Flipper (anatomy), Dorsal fin, Blubber, Animal echolocation, Melon (cetacean), Rostrum (anatomy), Countershading, Warm-blooded, Carnivore, Predation, Bait ball, Cetacean surfacing behaviour (bow riding and porpoising), Unihemispheric slow-wave sleep, Gestation, Orca, Bottlenose dolphin, Common bottlenose dolphin, Spinner dolphin, River dolphin, Common dolphin, Toothed whale, Marine mammal, Species, Habitat, Bycatch, Marine biology, Wildlife conservation and Signature whistle. Streamlined, rostrum and pod were also read in Wiktionary, the free dictionary (https://en.wiktionary.org/). The bottlenose dolphin, the orca, the spinner dolphin, the rostrum, the calf, gestation, the melon, the dorsal fin, porpoises and bycatch were checked a second time against pages of the U.S. National Oceanic and Atmospheric Administration: the species pages of NOAA Fisheries for the common bottlenose dolphin, the killer whale and the spinner dolphin (https://www.fisheries.noaa.gov/species/), Understanding Bycatch (https://www.fisheries.noaa.gov/insight/understanding-bycatch) and, among the ocean facts of the National Ocean Service, What's the difference between dolphins and porpoises? (https://oceanservice.noaa.gov/facts/dolphin_porpoise.html). The sources differ on the number of kinds of dolphin (Wikipedia: 40 living species; NOAA: 32 and five river dolphins), so the list says about 40, and on the spins of a spinner dolphin (NOAA: as many as four; Wikipedia: two to seven), so the list says several. The fact after each meaning is from the same pages. Licence: own work
How it works
This dolphin vocabulary worksheet prints dolphin, mammal, pod, calf, blowhole, fluke, flipper, dorsal fin, blubber, echolocation, cetacean and porpoise down the left and their meanings in another order down the right. An answer key is the last page.
Read the full guide
Body and behavior
Set opens on Dolphin basics. The second set has melon, rostrum, streamlined, countershading, warm-blooded, carnivore, prey, bait ball, bow riding, porpoising, unihemispheric sleep and gestation.
Dolphin kinds and their world
The third set has orca, bottlenose dolphin, spinner dolphin, river dolphin, common dolphin, toothed whale, marine mammal, species, habitat, bycatch, marine biologist and conservation.
Seals, sea otters, manatees and the great whales are on the ocean word search.
Questions and answers
What is the difference between a dolphin and a porpoise?
Their faces, fins and figures. A dolphin has a longer snout, cone-shaped teeth, a curved dorsal fin and a lean body. A porpoise has a small mouth, spade-shaped teeth, a triangular fin and a stouter body.
What is a group of dolphins called?
A pod, or sometimes a school. A male dolphin is called a bull and a female a cow.
How do dolphins communicate?
With clicks and whistles. Each bottlenose dolphin learns a signature whistle of its own that tells others who is calling. A calf builds its whistle from the sounds it hears, while keeping it different from those of the dolphins around it.
How smart are dolphins?
Dolphins have passed the mirror test, in which an animal uses a mirror to look at a mark on its body, though researchers still argue about what that shows. Some bottlenose dolphins in Australia teach their young to forage with a sponge over the snout.