Dolphin Information
Frequently Asked Question
What is an Atlantic
Bottlenose dolphin’s taxonomic classification?
What are the differences between
dolphins and porpoises?
How many different species of dolphins
are there?
What is the average lifespan of a dolphin?
Where do bottlenose dolphins live?
What do dolphins use their dorsal fin
for?
How do dolphins use their pectoral
fins?
How do dolphins use their flukes?
How many teeth do dolphins have?
Why do dolphins have teeth if they don’t
chew their fish?
What do dolphins eat?
How much do dolphins eat?
How do dolphins breathe?
Do dolphins sleep?
How can you distinguish between a male
and female dolphin?
Do dolphins have a sense of smell?
Do dolphins have good eyesight?
What is echolocation? How does
it work?
How well do dolphins hear?
How deep do dolphins dive?
When do dolphins reach sexual maturity?
How is a dolphin born?
What does a newborn calf look like?
How many calves does a female
typically have in her lifetime?
Do dolphins mate for life?
What is an Atlantic Bottlenose
dolphin’s taxonomic classification?
Kingdom: Animalia (Animals)
Phylum: Chordata (Chordates)
Subphylum: Vertebrata (Vertebrates)
Class: Mamalia (Mammals)
Order: Cetacea (Cetaceans)
Suborder: Odonoceti (Odontocetes)
Family: Delphinidae (Marine Dolphins)
Genus: Tursiops
Species: truncatus
Tursiops truncatus (bottlenose dolphins) are
cetaceans. The Order Cetacea is further divided into two
suborders, Odontoceti (toothed whales) and Mysticeti (baleen
whales). Mysticetes do not have teeth but have baleen
plates suspended from the roof of their mouth and have
two nasal openings (blowholes). Odontocetes (which include
bottlenose dolphins) have anywhere from 2-250 teeth and
a single nasal opening.
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What are the differences between
dolphins and porpoises?
There are several major differences between dolphins
and porpoises:
1) Dolphins have a longer and more pronounced beak (or
rostrum) than a porpoise.
2) Most of the vertebrae in a dolphin’s neck are
separate units, which gives them the ability to turn their
head. All vertebrae in a porpoise’s neck are fused,
which means they cannot turn their head to look left and
right. In order to do so, they must turn their entire
body.
3) Porpoises are generally smaller than dolphins.
4) Dolphins have cone shaped teeth. Porpoises have spade
shaped teeth.
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How many different species of
dolphins are there?
There are 32 different species of oceanic dolphins,
5 species of river dolphins, and 6 species of porpoises.
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What is the average lifespan
of a dolphin?
The lifespan of bottlenose dolphins varies greatly between
regions and populations. The average range is approximately
35-55 years, depending on the population..
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Where do bottlenose dolphins live?
Bottlenose dolphins are distributed all over the world
in both temperate and tropical waters. They occupy a variety
of habitats, ranging from nearshore, coastal areas to
deep offshore waters.
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What do dolphins use their dorsal
fin for?
:A dolphin’s dorsal fin has two, main functions:
stability and thermoregulation. The fin acts similarly
to the keel of a sailboat, helping the dolphin swim through
the water in a straight line. The dorsal fin is primarily
composed of cartilaginous tissue and lacks blubber. Therefore,
it is often used as a “thermal window”, allowing
dolphins to dump excess heat to their environment when
their internal body temperature gets too high.
Like a human fingerprint, there are no two dorsal fins
that are exactly identical. Each has its own unique shape,
height, thickness, and notches. Scientists utilize the
appearance of dorsal fins to identify individuals in the
wild. Many populations are extensively catalogued by dorsal
fin photographs, which allow scientists to study specific
groups of resident dolphins for many years.
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How do dolphins use their pectoral
fins?
The pectoral fins aid a dolphin in stopping and steering.
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How do dolphins use their flukes?
Dolphins use their flukes for propulsion through the
water. Fish move their tailfins from right to left (side-to-side).
Conversely, dolphins move their flukes up and down (dorsal-ventral).
These movements are powered by a very strong muscle called
the peduncle and allow bottlenose dolphins to swim upwards
of 20 mph!
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How many teeth do dolphins have?
Atlantic bottlenose dolphins have 80-100 cone-shaped
teeth. They possess only one set of teeth, which erupt
as calves (called “milk-teeth”). Therefore,
if they lose or break a tooth, it will not be replaced
by another.
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Why do dolphins have teeth if they
don’t chew their fish?
Dolphins do not chew their food but rather swallow their
prey whole. They typically swallow large fish head first,
so that they do not scratch their throat and esophagus
with the fish’s scales. They do need their teeth
to catch their prey, and the cone-shape aids in firm grasping.
Dolphins also use their teeth socially, in a behavior
called “raking”, in which they use their teeth
to scratch each other. This behavior is typically used
as a way to establish dominance, exhibit aggression, or
to moderate behavior. Dolphins have a very thick outer
(epidermal) skin layer. The surface of their epidermis
is replaced up to every 2 hours to promote a smooth hydrodynamic
surface (decreases drag when swimming) and to prevent
the colonization of fouling organisms on their skin.
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What do dolphins
eat?
At Dolphins Plus, the dolphins typically eat an assortment
of herring, capelin, sardines, silversides, smelt, and
mackerel. Sometimes, we feed them live shrimp and live
snapper. The dolphins also catch mangrove snapper and
grunts in their houses and love to chase glass minnows
and shrimp. In the wild, dolphins are opportunistic feeders,
and their diet is based on the species available in their
home range and include a wide variety of vertebrates and
invertebrates. Dolphins do not chew their fish, but may
use their teeth to catch and tear fish, typically swallowing
fish whole and head-first.
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How much do dolphins eat?
An average dolphin eats about 3-5% of their body weight
each day. An adult male typically eats about 20 pounds
of fish, while a nursing mother can eat upwards of 40
pounds of fish daily! Although it is not uncommon for
bottlenose dolphin calves to nurse for up to 4 years,
they usually begin to supplement their diet with fish
at about 6 months of age. A dolphin’s caloric needs
vary based on changes in water temperature and activity
level.
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How do dolphins breathe?
Dolphins are conscious breathers, which means they have
to think about every time they want to take a breath.
They respire through a nasal opening called the blowhole,
which is located on the top of their head. When resting,
their blowhole remains tightly shut. They are able to
hold their breath for an average of 4-5 minutes and a
maximum of about 10 minutes. Dolphins are efficient breathers.
They are able to exchange 80% of the air in their lungs
with each breath, while humans are only capable of exchanging
17%.
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Do dolphins sleep?
Due to the fact that dolphins are conscious breathers,
they cannot sleep the same way terrestrial mammals sleep.
One theory on sleeping in dolphins is that they alternately
rest each half of their brain for 2-3 minute intervals
throughout the course of the day. Dolphins have cross-ocular
connections like humans do, so they may close one eye
when resting the opposing side of their brain. Therefore,
half of their brain remains alert, enabling them to surface
when they need to breathe and constantly be aware of predators.
Dolphins sleep about 30% of their day (very similar to
the amount needed by humans), but they do not have an
extended sleep period.
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How can you distinguish between
a male and female dolphin?
Even though male and female genitalia are internal,
it’s fairly easy to discriminate one from the other.
On the underside of their peduncle, males have two, separate
slits, or grooves. One is called the genital groove and
the other the anal groove. They lie in line with each
other such that the grooves of a male resemble an exclamation
point. Females have one anogenital slit or groove and
a mammary slit on either side (will produce milk when
they are reproductively mature). Therefore, a female’s
underside resembles more of a division sign.
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Do dolphins have a sense of smell?
Dolphins lack olfactory receptors and therefore do not
have a sense of smell.
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Do dolphins have good eyesight?
Dolphins have 20/20 vision both above and below the
water. They are able to see in both environments, because
they can control the way light enters their eye via specialized,
ocular muscles. When viewing an object underwater, light
does not bend as it enters their eye, and when viewing
an object above water, the light is bent as it enters
their eye. Since their eyes are on the sides of their
head, dolphins (and most small toothed whales) have both
monoscopic and stereoscopic vision. Seeing monoscopically
means a dolphin is able to independently process two different
images at the same time. Dolphins are also able to see
stereoscopically, focusing both eyes downward toward their
stomach (most in focus about 3-5 feet away). Dolphins
see 173 degrees to each side from the tip of their rostrum
to the tip of their tail. They have three known blind
spots – directly above them, directly behind them,
and directly in front of their rostrum. It is still unclear
as to whether dolphins can see in color. They posses both
cones and rods in their eyes, but some scientists believe
this may contribute to improved night/low-light vision
vs. the ability to see in color.
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What is echolocation? How
does it work?
Echolocation works similarly to an ultrasound. It gives
a dolphin the capacity to explore their environment 3
dimensionally and aids in navigation and hunting in low
light and low visibility environments. The emit sounds,
or clicks, from their nasal passages, which are then passed
through their melon (forehead). The melon is filled with
fatty tissue and fluid and acts like an acoustic lens
to focus the sounds in different directions. The sound
waves then bounce off of objects of interest and are received
by the dolphin’s lower jaw as an echo. This information
is then passed to the brain via the inner ear. Echolocation
is very efficient. Bottlenose dolphins are capable of
distinguishing an object the size of a ping-pong ball
from a football field away.
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How well do dolphins hear?
Dolphins hear about 7.5 times better than we do. A dolphin’s
hearing range is between 0.2 – 150 kHz, with peak
sensitivity falling between 8 - 90 kHz. A human’s
hearing range is between 0.2 – 17 kHz, with peak
sensitivity falling between 0.5 – 4 kHz. Thus, humans
are incapable of hearing a large range of sounds both
produced and heard by dolphins.
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How deep do dolphins dive?
An average dive for a bottlenose dolphin can be anywhere
from 10ft to 150ft.
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When do dolphins reach sexual
maturity?
The age at sexual maturity varies greatly in bottlenose
dolphins between regions and populations. Sexual maturity
is usually a function of size, not age. A female typically
reaches sexual maturity when she has attained 85-95% of
her mean adult body length. This ranges from 7-12 years,
depending on the population. Males attain sexual maturity
later than females, typically occurring between 10-15
years.
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How is a dolphin born?
Dolphins are mammals and therefore give birth to live
young. The gestation period for bottlenose dolphins is
approximately 12 months, and calves are usually born tail
first. The birth process can take anywhere from 30 minutes
to 3 hours.
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What does a newborn dolphin calf
look like?
At birth, a bottlenose dolphin calf is about 3 –
4 feet long and weighs 30 – 40 pounds. They are
born with their dorsal fin flat on their back and their
tail flukes curled. The dorsal fin is usually standing
erect by about 24-48 hours after birth, though it may
remain wobbly for many years. Their flukes also flatten
out within 24-48 hours. A newborn calf is generally dark
in color with light stripes called fetal folds.
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How many calves does a female
typically have in her lifetime?
Females begin to reproduce successfully at about 7-12
years of age. Due to a high investment in maternal care,
the average interbirth interval in bottlenose dolphins
is about 4-5 years. There is no clear evidence of reproductive
senescence (“old-age”) in dolphins, with female
dolphins successfully reproducing into their late forties.
Therefore, it would be possible for a dolphin to give
birth to 11+ calves in their lifetime. Keep in mind that
not all births are successful (70-80% in the wild).
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Do dolphins mate for life?
Dolphins are not monogamous animals and do not typically
mate for life. Some believe bonds between males are the
strongest and most enduring in dolphin societies.
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