Welcome to the I Can't Sleep Podcast,
Where I help you drift off one fact at a time.
I'm your host,
Benjamin Boster,
And today's episode is about elephants.
Elephants are the largest living land animals.
Three living species are currently recognized.
The African Bush Elephant,
Loxodonta africana.
The African Forest Elephant,
Loxodonta cyclotus.
And the Asian Elephant,
Eliphus maximus.
They are the only surviving members of the family Elephantidae,
And they order proboscilia.
Extinct relatives include mammoths and mastodons.
Distinctive features of elephants include a long proboscis called a trunk,
Tusks,
Large ear flaps,
Pillar-like legs,
And tough but sensitive gray skin.
The trunk is prehensile,
Bringing food and water to the mouth and grasping objects.
Tusks,
Which are derived from the incisor teeth,
Serve both as weapons and as tools for moving objects and digging.
The large ear flaps assist in maintaining a constant body temperature,
As well as in communication.
African elephants have larger ears and concave backs,
Whereas Asian elephants have smaller ears and convex or level backs.
Elephants are scattered throughout sub-Saharan Africa,
South Asia,
And Southeast Asia,
And are found in different habitats,
Including savannas,
Forests,
Deserts,
And marshes.
They are herbivorous,
And they stay near water when it is accessible.
They are considered to be keystone species due to their impact on their environments.
Elephants have a fission-fusion society,
In which multiple family groups come together to socialize.
Females,
Cows,
Tend to live in family groups,
Which can consist of one female with her calves,
Or several related females with offspring.
The leader of a female group,
Usually the oldest cow,
Is known as the matriarch.
Males,
Bulls,
Leave their family groups when they reach puberty,
And may live alone or with other males.
Adult bulls mostly interact with family groups when looking for a mate.
Calves are the center of attention in their family groups,
And rely on their mothers for as long as three years.
Elephants can live up to 70 years in the wild.
They communicate by touch,
Sight,
Smell,
And sound.
Elephants use infrasound and seismic communication over long distances.
Elephant intelligence has been compared with that of primates and cetaceans.
They appear to have self-awareness,
And possibly show concern for dying and dead individuals of their kind.
The word elephant is derived from the Latin word elephas,
Genitive elephantus,
Elephant,
Which is the Latinized form of the ancient Greek elephas,
Genitive elephantos.
Probably from a non-Indo-European language like Phoenician.
It is attested in Mycenaean Greek as erepa,
Genitive erepato,
In Linear B syllabic script.
As in Mycenaean Greek,
Homer used the Greek word to mean ivory,
But after the time of Herodotus,
It also referred to the animal.
The word elephant appears in Middle English as olifant in circa 1300,
And was borrowed from Old French olifant in the 12th century.
Elephants are the largest living terrestrial animals.
The skeleton is made up of 326 to 351 bones.
The vertebrae are connected by tight joints,
Which limit the backbone's flexibility.
African elephants have 21 pairs of ribs,
While Asian elephants have 19 or 20 pairs.
The skull contains air cavities,
Sinuses,
That reduce the weight of the skull while maintaining overall strength.
The cavities give the inside of the skull a honeycomb-like appearance.
By contrast,
The lower jaw is dense.
The cranium is particularly large and provides enough room for the attachment of muscles to support the entire head.
The skull is built to withstand great stress,
Particularly when fighting or using the tusks.
The brain is surrounded by arches in the skull,
Which serve as protection.
Because of the size of the head,
The neck is relatively short to provide better support.
Elephants are hemiotherms and maintain their average body temperature at roughly 36 degrees Celsius,
With a minimum of 35.
2 degrees Celsius during the cool season and a maximum of 38 degrees Celsius during the hot,
Dry season.
Elephant ear flaps,
Or pini,
Are 1 to 2 millimeters thick in the middle,
With a thinner tip and supported by a thicker base.
They contain numerous blood vessels called capillaries.
Warm blood flows into the capillaries,
Releasing excess heat into the environment.
This effect is increased by flapping the ears back and forth.
Larger ear surfaces contain more capillaries,
And more heat can be released.
Of all the elephants,
African bush elephants live in the hottest climates and have the largest ear flaps.
The ossicles are adapted for hearing low frequencies,
Being most sensitive at 1 kilohertz.
Lacking a lacrimal apparatus,
Or tear duct,
The eye relies on the harderian gland in the orbit to keep it moist.
A durable nictitating membrane shields the globe.
The animal's field of vision is compromised by the location and limited mobility of the eyes.
Elephants are dichromats,
And they can see well in dim light but not in bright light.
The elongated and prehensile trunk,
Or proboscis,
Consists of both the nose and upper lip,
Which fuse in early fetal development.
This versatile appendage contains up to 150,
000 separate muscle fascicles,
With no bone and little fat.
These paired muscles consist of two major types,
Superficial,
Surface,
And internal.
The former are divided into dorsal,
Ventral,
And lateral muscles,
While the latter are divided into transverse and radiating muscles.
The muscles of the trunk connect to a bony opening in the skull.
The nasal septum consists of small elastic muscles between the nostrils,
Which are divided by cartilage at the base.
A unique proboscis nerve,
A combination of the maxillary and facial nerves,
Lines each side of the appendage.
As a muscular hydrostat,
The trunk moves through finely controlled muscle contractions,
Working both with and against each other.
Using three basic movements,
Bending,
Twisting,
And longitudinal stretching or retracting,
The trunk has near unlimited flexibility.
Objects grasped by the end of the trunk can be moved to the mouth by curving the appendage inward.
The trunk can also bend at different points by creating stiffened pseudo-joints.
The tip can be moved in a way similar to the human hand.
The skin is more elastic on the dorsal side of the elephant trunk than underneath.
Allowing the animal to stretch and coil while maintaining a strong grasp.
The flexibility of the trunk is aided by the numerous wrinkles in the skin.
The African elephants have two finger-like extensions at the tip of the trunk that allow them to pluck small food.
The Asian elephant has only one and relies more on wrapping around a food item.
Asian elephant trunks have better motor coordination.
The trunk's extreme flexibility allows it to forage and wrestle other elephants with it.
It is powerful enough to lift up to 350 kilograms.
But it also has the precision to crack a peanut shell without breaking the seed.
With its trunk,
An elephant can reach items up to 7 meters high and dig for water in the mud or sand below.
It also uses it to clean itself.
Individuals may show lateral preference when grasping with their trunks.
Some prefer to twist them to the left,
Others to the right.
Elephant trunks are capable of powerful siphoning.
They can expand their nostrils by 30%,
Leading to a 64% greater nasal volume and can breathe in almost 30 times faster than a human sneeze at over 150 meters per second.
They suck up water which is squirted into the mouth or over the body.
The trunk of an adult Asian elephant is capable of retaining 8.
5 liters of water.
They can also sprinkle dust or grass on themselves.
When underwater,
The elephant uses its trunk as a snorkel.
The trunk also acts as a sense organ.
Its sense of smell may be four times greater than a bloodhound's nose.
The infraorbital nerve,
Which makes the trunk sensitive to touch,
Is thicker than both the optic and auditory nerves.
Whiskers grow all along the trunk and are particularly packed at the tip where they contribute to its tactile sensitivity.
Unlike those of many mammals,
Such as cats and rats,
Elephant whiskers do not move independently to sense the environment.
The trunk itself must move to bring the whiskers into contact with nearby objects.
Whiskers grow in rows along each side on the ventral surface of the trunk,
Which is thought to be essential in helping elephants balance objects there,
Whereas they are more evenly arranged on the dorsal surface.
The number and patterns of whiskers are distinctly different between species.
Elephants usually have 26 teeth,
The incisors,
Known as the tusks,
12 deciduous premolars,
And 12 molars.
Unlike most mammals,
Teeth are not replaced by new ones emerging from the jaws vertically.
Instead,
New teeth start at the back of the mouth and push out the old ones.
The first chewing tooth on each side of the jaw falls out when the elephant is 2 or 3 years old.
This is followed by four more tooth replacements at the ages of 4 to 6,
9 to 15,
18 to 28,
And finally in their early 40s.
The final,
Usually sixth,
Set must last the elephant the rest of its life.
Elephant teeth have loop-shaped dental ridges,
Which are more diamond-shaped in African elephants.
The tusks of an elephant are modified second incisors in the upper jaw.
They replace deciduous milk teeth at 6 to 12 months of age,
And keep growing at about 17 cm a year.
As the tusk develops,
It is topped with smooth cone-shaped enamel that eventually wanes.
The dentin is known as ivory and has a cross-section of intersecting lines,
Known as engine turning,
Which create diamond-shaped patterns.
Being living tissue,
Tusks are fairly soft,
And about as dense as the mineral calcite.
The tusk protrudes from a socket in the skull,
And most of it is external.
At least one-third of the tusk contains the pulp,
And some have nerves that stretch even further.
Tusks function in digging,
Debarking,
Marking,
Moving objects,
And fighting.
Elephants are usually right- or left-tusked,
Similar to humans,
Who are typically right- or left-handed.
The dominant,
Or master,
Tusk is typically more worn down,
As it is shorter and blunter.
For African elephants,
Tusks are present in both males and females,
And are around the same length in both sexes,
Reaching up to 300 cm.
But those of males tend to be more massive.
In the Asian species,
Only the males have large tusks.
Female Asians have very small tusks,
Or none at all.
Tuskless males exist,
And are particularly common among Sri Lankan elephants.
Asian males can have tusks as long as Africans,
But they're usually slimmer and lighter.
The largest recorded was 302 cm long,
And weighed 39 kg.
An elephant's skin is generally very tough,
At 2.
5 cm thick on the back and parts of the head.
Elephants are typically grey,
But African elephants look brown or reddish after rolling in coloured mud.
Asian elephants have some patches of depigmentation,
Particularly on the head.
Calves have brownish or reddish hair,
With the head and back being particularly hairy.
As elephants mature,
Their hair darkens and becomes sparser,
But dense concentrations of hair and bristles remain on the tip of the tail and parts of the head.
Normally the skin of an Asian elephant is covered with more hair than its African counterpart.
Their hair is thought to help them lose heat in their hot environments.
Although tough,
An elephant's skin is very sensitive,
And requires mud baths to maintain moisture and protection from burning and insect bites.
After bathing,
The elephant will usually use its trunk to blow dust onto its body,
Which dries into a protective crust.
Elephants have difficulty releasing heat through the skin because of their low surface area to volume ratio,
Which is many times smaller than that of a human.
They have even been observed lifting up their legs to expose their soles to the air.
Elephants only have sweat glands between their toes,
But the skin allows water to disperse and evaporate,
Cooling the animal.
In addition,
Cracks in the skin may reduce dehydration and allow for increased thermal regulation in the long term.
To support the animal's weight,
An elephant's limbs are positioned more vertically under the body than in most other mammals.
The long bones of the limbs have cancellous bones in place of medullary cavities.
This strengthens the bones while still allowing hematopoiesis,
Blood cell creation.
Both the front and hind limbs can support an elephant's weight,
Although 60% is borne by the front.
The position of the limbs and leg bones allows an elephant to stand still for extended periods of time without tiring.
Elephants are incapable of turning their manus because the ulna and radius of the front legs are secured in pronation.
Elephants may also lack the pronator quadratus and pronator teres muscles,
Or have very small ones.
The circular feet of an elephant have soft tissues or cushion pads beneath the manus or pes,
Which allow them to bear the animal's great mass.
They appear to have a sesamoid or extra toe similar in placement to a giant panda's extra thumb.
That also helps in weight distribution.
As many as five toenails can be found on both the front and hind feet.
Elephants can move both forward and backward,
But are incapable of trotting,
Jumping,
Or galloping.
They can move on land only by walking or ambling,
A faster gait similar to running.
In walking,
The legs act as pendulums,
With the hips and shoulders moving up and down while the foot is on the ground.
The fast gait does not meet all the criteria of running,
Since there is no point where all the feet are off the ground,
Although the elephant uses its legs much like other running animals,
And can move faster by quickening its stride.
Fast moving elephants appear to run with their front legs,
But walk with their hind legs,
And can reach a top speed of 25 km per hour.
At this speed,
Most other quadrupeds are well into a gallop,
Even accounting for leg length.
Spring-like kinetics could explain the difference between the motion of elephants and other animals.
The cushion pads expand and contract,
And reduce both the pain and noise that would come from a very heavy animal moving.
Elephants are capable swimmers.
They can swim for up to six hours while completely waterborne,
Moving at 2.
1 km per hour,
And traversing up to 48 km continuously.
The brain of an elephant weighs 4.
5 to 5.
5 kg,
Compared to 1.
6 kg for a human brain.
It is the largest of all terrestrial animals.
While the elephant brain is larger overall,
It is proportionally smaller than the human brain.
At birth,
An elephant's brain already weighs 30 to 40% of its adult weight.
The cerebrum and cerebellum are well developed,
And the temporal lobes are so large that they bulge out laterally.
Their temporal lobes are proportionally larger than those of other animals,
Including humans.
The throat of an elephant appears to contain a pouch where it can store water for later use.
The larynx of the elephant is the largest known among mammals.
The vocal folds are anchored close to the epiglottis base.
When comparing an elephant's vocal folds to those of a human,
An elephant's are proportionally longer,
Thicker,
With a greater cross-sectional area.
In addition,
They are located further up the vocal tract with an acute slope.
The heart of an elephant weighs 12 to 21 kg.
Its apex has two pointed ends,
An unusual trait among mammals.
In addition,
The ventricles of the heart split towards the top,
A trait also found in sirenians.
When upright,
The elephant's heart beats around 28 beats per minute,
And actually speeds up to 35 beats when it lies down.
The blood vessels are thick and wide and can hold up under high blood pressure.
The lungs are attached to the diaphragm,
And breathing relies less on the expanding of the ribcage.
Connective tissue exists in place of the pleural cavity.
This may allow the animal to deal with the pressure differences when its body is underwater and its trunk is breaking the surface for air.
Elephants breathe mostly with the trunk,
But also with the mouth.
They have a hindgut fermentation system,
And their large and small intestines together reach 35 meters in length.
Less than half of an elephant's food intake gets digested,
Despite the process lasting all day.
Elephants are herbivorous,
And will eat leaves,
Twigs,
Fruit,
Bark,
Grass,
And roots.
African elephants mostly browse,
While Asian elephants mainly graze.
They can eat as much as 300 kilograms of food and drink 40 liters of water in a day.
Elephants tend to stay near water sources.
They have morning,
Afternoon,
And nighttime feeding sessions.
At midday,
Elephants rest under trees and may doze off while standing.
Sleeping occurs at night while the animals lie down.
Elephants average 3 to 4 hours of sleep per day.
Both males and family groups typically move no more than 20 kilometers a day,
But distances as far as 180 kilometers have been recorded in the Atosha region of Namibia.
Elephants go on seasonal migrations in response to changes in environmental conditions.
In northern Botswana,
They travel 325 kilometers to the Chobe River after the local waterholes dry up in late August.
Because of their large size,
Elephants have a huge impact on their environments and are considered keystone species.
Their habit of uprooting trees and undergrowth can transform savanna into grasslands.
Smaller herbivores can access trees mowed down by elephants.
When they dig for water during droughts,
They create waterholes that can be used by other animals.
When they use waterholes,
They end up making them bigger.
At Mount Elgin,
Elephants dig through caves and pave the way for ungulates,
Hyraxes,
Bats,
Birds,
And insects.
Elephants are important seed dispersers.
African forest elephants consume and deposit many seeds over great distances,
With either no effect or positive effect on germination.
In Asian forests,
Large seeds require giant herbivores like elephants and rhinoceros for transport and dispersal.
This ecological niche cannot be filled by the smaller Malayan tapir.
Because most of the food elephants eat goes undigested,
Their dung can provide food for other animals,
Such as dung beetles and monkeys.
Elephants are generally gregarious animals.
African bush elephants,
In particular,
Have a complex stratified social structure.
Female elephants spend their entire lives in tight-knit matrilineal family groups.
They are led by the matriarch,
Who is often the oldest female.
She remains leader of the group until death,
Or if she no longer has the energy for the role.
A study in zoo elephants found that the death of the matriarch led to greater stress in the surviving elephants.
When her tenure is over,
The matriarch's eldest daughter takes her place instead of her sister if present.
One study found that younger matriarchs take potential threats less seriously.
Large family groups may split if they cannot be supported by local resources.
