What animal has the longest juvenile period?

What animal has the longest juvenile period?

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I just heard the following complaint from a comedienne.

Humans are the only animal that is completely useless for the first twenty five years of life.

Obviously this is just a joke but it is true that primates and especially humans do have profoundly long juvenile periods compared with most animals. It's got me wondering whether humans really do spend the most time in sexual immaturity.

Unfortunately I have found this question hard to search because Google thinks I'm asking about the longest gestation period (which seems to be a much more popular question). To be clear, I am not asking about the longest gestation period.

As you indicate in your question, the average age of sexual maturity is probably the best way to approach this, since immaturity is usually how juveniles are defined. Age of puberty is also different in boys and girls (the same goes for many animals), and has also decreased in the 21 century. However, as an historical average for humans 15 years is probably fair, even though there is a lot of variance. That is high compared to most animals, but there are some that have similar or higher ages of maturation, e.g.:

  • Cicadas in the genus Magcicada, which can have a 17 year life cycle

  • Elephants reach sexual maturity at about an age of 8-15 years, but usually dont start to breed until they are at least 18-20 years (see e.g. and Association of Zoos and Aquariums). Males mature and start reproducing later than females, and in practice it is mostly older bulls that reproduce.

  • The Nile crocodile, which reach sexual maturity at at an age of 12-16 years (largely dependent of body size though).

  • Some species of Tortoise reach maturity at ages 13-16 years (e.g. Gopherus sp, see Germano, 1994), and, again, which is largely due to body size and growth rate. Captive bred individuals can mature more quickly.

As you can see, there is a difference between sexual maturity and reproductive age. To actually be able to reproduce, especially in some male mammals, you often need experience and size, which means that reproduction is delayed in practice. Whether this period from sexual maturity (with respect to producing mature eggs/sperm) to reproductive age should be defined as least partially as "adolescence" will affect how humans compare to other animals. In my examples, I have focused on sexual maturity (which usually has less variation between individuals).

For other examples, you might want to look at insects other than Cicadas that have delayed larval stages. This does for many woodliving beetles, where development times can be very variable, and under poor conditions take up to 20-30 years. This is usually not the norm though.

When searching for other examples, use the terms "age of maturation, "reproductive age", "sexual maturity" etc, to focus on sexual maturation and not gestation.

This article provides general facts about Tuataras, one of which is:

Tuataras reproduce slowly. They take 10-20 years to reach sexual maturity. Males can mate every year, but females breed every two to five years. It takes the female between one and three years to provide eggs with yolk, and up to seven months to form the shell. Then it takes an additional 12 to 15 months from copulation to hatching, possibly the longest incubation rate of any reptile.

A male tuatara named Henry, living at the Southland Museum and Art Gallery, became a first-time father at the age of 111. He fathered 11 babies with a female named Mildred, believed to be in her seventies.

Those creatures are therefore one of the many that can be added to the list of the above answer.

The Greenland shark (Somniosus microcephalus) has been reported to need at least 156 ± 22 years reach to sexual maturity1. This is also thought to be the vertebrate with the longest lifespan.


1: Nielsen, J., Hedeholm, R. B., Heinemeier, J., Bushnell, P. G., Christiansen, J. S., Olsen, J.,… & Steffensen, J. F. (2016). Eye lens radiocarbon reveals centuries of longevity in the Greenland shark (Somniosus microcephalus). Science, 353(6300), 702-704.

What animal has the longest juvenile period? - Biology

By the end of this section, you will be able to:

  • Describe the features that characterized the earliest animals and when they appeared on earth
  • Explain the significance of the Cambrian period for animal evolution and the changes in animal diversity that took place during that time
  • Describe some of the unresolved questions surrounding the Cambrian explosion
  • Discuss the implications of mass animal extinctions that have occurred in evolutionary history

Many questions regarding the origins and evolutionary history of the animal kingdom continue to be researched and debated, as new fossil and molecular evidence change prevailing theories. Some of these questions include the following: How long have animals existed on Earth? What were the earliest members of the animal kingdom, and what organism was their common ancestor? While animal diversity increased during the Cambrian period of the Paleozoic era, 530 million years ago, modern fossil evidence suggests that primitive animal species existed much earlier.

Organisms: 3 Most Important Phases of Organisms

There are three phases in an organism’s life: juvenile phase, reproductive phase and senescent phase.

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1. Juvenile Phase/Vegetative Phase:

It is pre-reproductive phase in the life cycle of an individual.

It is the period of growth between the births of an individual up to reproductive maturity. This phase has different structures such as different shapes of leaves different colours of feathers of birds, different protections of the body. Juvenile phase is known as vegetative phase in plants. This phase is of different durations in different organisms.

2. Reproductive Phase (Maturity Phase):

The organisms reproduce offspring during this phase. Reproductive organs develop and mature during this period which is called puberty. Appearance of flowers in higher plants indicates sexual maturity. Sexually there are two types of flowering plants: monocarpic and polycarpic.

(i) Monocarpic Plants:

These plants flower only once in their life. After flowering they produce fruits and die. All annual (e.g., Wheat, Rice) and biennial plants (e.g., Carrot, Radish) are monocarpic. A few perennial plants are also monocarpic. A few plants show unusual certain bamboo species, (e.g., Bambusa tulda) flower only once in their life time, usually after 50-100 years.

They produce large number of fruits and then die. Strobilanthus kunthiana (Neelakuranji) flowers once in 12 years. The last time this plant flowered during September—October 2006. It is found in hilly areas in Kerala, Karnataka and Tamil Nadu and attracted a large number of tourists. Thus reproductive phase is also of variable duration in different organisms.

(ii) Polycarpic Plants:

These plants are perennial and flower repeatedly at intervals every year, e.g., Apple, Mango, Orange, Grape vine). Very few perennial plants have flowers throughout the year (e.g., China Rose — Shoe Flower).

On the basis of time of breeding, animals are of two types: seasonal breeders and continuous breeders.

They reproduce at particular period of the year such as frog, lizards, most birds, deer, etc.

(ii) Continuous Breeders:

These animals continue to breed throughout their sexual maturity. Examples are honey bee, queen, poultry, rabbit, mice, cattle, etc.

In females of placental mammals, there are cyclical changes in ovaries, accessory reproductive ducts and hormones during the reproductive phase. These are of two types. In primates (monkeys, apes and humans) such cyclical changes during reproductive phase is called menstrual cycle whereas in non-primate mammals like cows, sheep, rats, deer, dogs, tiger, etc. such cyclical changes during reproduction are called oestrous cycle.

3. Senescent Phase (Senescence, Ageing):

It begins from the end of the reproductive phase. The terminal irreversible stage of ageing is called senescence. This is the last phase of life span, senescence ultimately leads to death. In both plants and animals hormones are responsible for the change over from one phase to another. Hormones and certain environmental factors regulate the reproductive processes and the behaviour of the organisms.

Sexuality in Organisms:

In most primitive sexually reproducing organisms, there is no morphological or physiological difference in the functional gametes. The gametes belong to the same parent. Such organisms are called homothallic (bisexual condition), e.g., Mucor mucedo.

When the functional gametes belong to different parents as in Rhizopus stolonifer, and there is no morphological or physical difference, these organisms are called heterothallic (unisexual condition). In higher organisms, sex organs developed, and they became male and female organisms.

In most flowering plants, both male and female sex organs (stamens and carpels) occur in the same flower. Such plants are called hermaphrodite or bisexual, e.g., sweet potato. In some flowering plants, male flowers (staminate flowers) and female flowers (pistillate flowers) are borne on different plants.

These plants are called dioecious plants. Plants are either male or female, e.g., Date Palm and Papaya. When both male and female flowers are present on the same plants they are called monoecious plants, e.g., Maize, coconut and Cucurbits. Lower plants are also monoecious and dioecious.

Chara often bears both male (antheridium) and female (oogonium) sex organs. Marchantia a liverwort is dioecious. Here, the female plant bears archegonia over the archegoniophore. The male plant has antheridia over the antheridiophore.

Orangutan News

Orangutans have long, sparse orange or reddish hair unequally distributed over their bodies. They have large jaws and flattened noses in concave faces.

Orangutans are the largest arboreal mammals and are very well adapted to life in the trees, with arms much longer than their legs. They have grasping hands and feet with long curved fingers and toes. They have distinctive fingerprints and no visible external tails.

You can typically tell male and female orangutans apart by looking at them. Males and females have flabby throat sacs, which become very large in adult males. Adult males have deep chests and much longer body hair than females do. Males also typically develop large cheek pads, which demonstrate genetic fitness and amplify their long calls.

Orangutans can brachiate — swing hand over hand — but they normally move cautiously through large trees by climbing and walking. This allows them to distribute their weight among the branches. Orangutans' hands make them graceful and swift while swinging, but it makes walking on the ground very slow and awkward.

Orangutans sometimes travel on the ground when going long distances because appropriate sized branches may not always be available. When on the ground, they use all four limbs, supporting themselves on the sides of clenched fists, or occasionally walk on upright on two legs. Orangutans also come down if there is a need to find food and water elsewhere, for example, if there is a drought or fire.

It can be difficult to tell Sumatran and Bornean orangutans apart. Generally, Sumatran orangutans are lighter in color, have longer body hair and less pendulous throat sacs than Bornean orangutans, but the only reliable way to tell the difference between Sumatran and Bornean orangutans is by looking at their chromosomes.

Wild adult females weigh between 80 and 120 pounds (36 and 54 kilograms), while wild adult males weigh 170 and 220 pounds (77 and 100 kilograms). Animals in zoos tend to be 50 to 100 pounds (23 to 45 kilograms) heavier due to a consistent supply of high quality food.

Orangutans live on the Indonesian island of Sumatra and in both the Malaysian and Indonesian portions of the island of Borneo. They are highly arboreal and live in all levels of the forest, from floor to canopy. Habitats range from peat swamp forests near sea level to mountainous forests almost a mile (1.6 kilometers) above sea level. As humans have moved into the lower elevations — the orangutan's original habitat — orangutans have moved up the mountainsides.

Orangutans are more solitary than other great apes and do not have as complicated a vocal repertoire as some of the more gregarious primates. Orangutans rely more on facial expressions and body language to communicate. Among the vocalizations they use are kiss-squeak and belching vocalizations when they are upset, and a loud, deep long call used typically by males for long-distance communication.

This long call resonates in the male's enlarged throat sac and echoes through the forest. It is used to locate and advertise the male's presence to females or warn other males away. It can be heard a kilometer or more away (more than half a mile). Certain vocalizations such as nest smacks and throat scrapes are considered cultural and are found in some populations of wild orangutans but not in others.

Orangutans eat primarily fruit and play an important role dispersing seeds through defecation. Although they spend a majority of their total foraging time feeding on fruits whenever they are available, orangutans also eat insects and flowers, and during times of fruit scarcity, fall back on a variety of other types of food, including inner bark, leaves, and other vegetation. Orangutans have also been observed eating mineral-rich soil, bird eggs and, occasionally, small mammals such as rats and slow lorises. Orangutans get water from a variety of sources, including tree holes and leaves that fill with water during the rainy season.

When water is difficult to reach, orangutans chew leaves to make a pulpy sponge to soak up the water. Orangutans in some wild populations modify small sticks, which they hold in their lips while probing in tree trunks for food such as honey. Orangutans exhibit a variety of geographically variable innovative behaviors, some of which are considered cultural. Among these behaviors are certain forms of tool-use, including the modification of sticks by a population of Sumatran orangutans to open Neesia fruits and more efficiently harvest their seeds.

Orangutans have a long period of infant dependency (weaning around age six or seven) with exceptionally long inter-birth intervals (at least eight years in Sumatran orangutans and a little bit shorter in Bornean orangutans). This may be at least partially due to diet. Mothers teach their infants what food to eat, where to find that food, in which trees and during which seasons. Young orangutans must learn about hundreds of varieties of fruit, where to find them seasonally and how to open them.

In the morning, the orangutans at the Zoo are often fed together. Food items are cut up and spread over a wide area. In the afternoon, individuals are separated so each animal gets its share of preferred food items. In the morning, the animals are given greens, green beans, carrots, broccoli and primate chow. In the evening, they are given bananas, apples, primate chow, greens and a selection of other fruits and vegetables. Forage items placed in hay for the orangutans include air-popped popcorn, diced fruits and veggies, beans and sunflower seeds. Browse (fresh tree trimmings) is given daily.

Orangutans live semi-solitary lives in the wild. While they are the most solitary of the great apes, it should be noted that orangutans are highly social and exhibit social tolerance during times of high fruit abundance when they come together in aggregations known as parties.

Adult females travel through the forest with their dependent offspring. Females do not live in tight social groups, but they are familiar with and have relationships with other females in the area. Adult males have large home ranges that overlap those of multiple females. Males typically range alone except when they mate with females, forming consortships that last up to several weeks. Males may also join other orangutans of various sexes and ages in feeding aggregations. Individuals within a certain range appear to know others and interact comfortably when they encounter each other.

Flanged males (males with flanges, also known as cheek pads) use long calls to attract females and to discourage the approach of other males. Throat sacs add resonance to long calls, which are specific to individual males. Orangutans of all ages and sexes give kiss squeak vocalizations, engage in branch-shaking displays and sometimes even uproot dead trees when confronted by unknown individuals or when they are not habituated to the presence of human observers. In zoos, displays consist of throwing around tubs and other objects.

Orangutans' social structure is connected to the distribution of food resources, primarily fruit. Orangutans spread out to get enough to eat throughout the year. Because they exhibit high social tolerance, orangutans are quite adaptable to living together when food is plentiful and when there is adequate housing space, such as at the Smithsonian's National Zoo. Animals will segregate themselves as needed, and as males mature, they may become more territorial and often must be housed separately.

Orangutans usually have a single baby, and twins are rare. Gestation is seven-and-a-half to eight-and-a-half months. From birth, orangutan infants cling to their mothers as they maneuver through the trees. The orangutan has the longest period of dependence on the mother of any other land-dwelling animal, including humans. Infant orangutans can nurse until they are six to seven years old. However, weaning is highly variable, depending on the mother. It is thought that weaning occurs sooner if food is abundant and the infant can switch to solids.

A female will only have a baby about every seven to nine years, resulting in only four to five babies in her lifetime. The inter-birth interval is somewhat longer in Sumatran orangutans than it is in Bornean orangutans researchers are still trying to determine why this is the case.

After reaching adolescence at four or five years, these animals become increasingly independent of their mothers. Sexual maturity for males and females in zoos is around six years, although it can take up to 10 years or more for a wild female to mature and longer than that for males. Females may stay with their mothers until they are well into their teens, allowing them to observe mothering skills as they watch their younger siblings being raised. Physical maturity, especially in males, may not be reached for several years after sexual maturity.

The presence of a fully mature dominant male may suppress secondary sexual characteristics (long hair, face pads, beards and enlarged throat sacs) in other less dominant males, and, in some cases, a wild male orangutan may never develop cheek pads. This suppression of secondary sexual characteristic does not, however, suppress his fertility, and it has been shown that unflanged male orangutans are as successful in siring offspring as fully flanged males.

Most animals copulate only when the female is ovulating, but orangutans may copulate daily during several-day long consortships in the wild or when housed together socially in zoos. Research indicates that ovulating females seek out adult males for copulation. Females and males usually mate willingly, but sometimes a male will pursue a female and forcibly copulate with her. Both are natural behaviors for wild and zoo orangutans.

Orangutans typically build sleeping nests above the ground in various positions of one or more trees. They usually build and sleep in a fresh nest each night, but they will sometimes re-enter or rebuild an older nest. They will also sometimes nap in a less carefully constructed day nest.

The median life expectancy for male Bornean orangutans is about 27 years and for male Sumatran orangutans is about 25 years. The median life expectancy for female Sumatran orangutans is about 32 years. There is not enough available data on the life expectancy of female Bornean orangutans.

Bornean, Sumatran and Tapanuli orangutans are critically endangered.

The risk of extinction for the critically endangered Bornean orangutan is very high. Their population levels have dropped more than 50 percent over the past 60 years, and their habitat has declined by over 80 percent in the past 20 years. The total population of wild Bornean orangutans is estimated to be approximately 70,000-100,000 individuals. On Sumatra, the orangutan population is approximately 13,800 individuals. The Tapanuli orangutan populations is approximately 800 individuals.

The inaccessibility of much of their range, poor visibility in dense forests and the nature of the animals makes it difficult to survey with precision. Sumatran orangutans are listed among the 25 most endangered primates in the world and Bornean, Sumatran and Tapanuli orangutans are in imminent danger of going extinct. Population numbers of Sumatran orangutans have declined over 80 percent in the past 75 years, and it is projected that this decline will continue. Loss of habitat is a major threat to orangutans, with many living outside of protected areas and, as a result, at greater risk of losing their habitat to logging and land clearings.

One of the most serious threats to orangutan viability is the unsustainable practice of timber extraction in Indonesia and Malaysia. Habitat destruction and the subsequent degradation, either from commercial timber harvesting or conversion of land to agriculture (particularly palm oil), poses a very serious threat to these arboreal apes. Moreover, the illegal pet trade is booming in Southeast Asia and infant orangutans are very popular pets. The low density, small population size and increasing pressure on their habitat, coupled with certain factors of orangutan behavioral ecology including diet, low reproductive rates, slow maturation and the longest inter-birth interval of any land-based mammal, make the orangutan extremely vulnerable to extinction in the near future if threats are not minimized.

Another significant threat to orangutan survival is hunting for meat and capture of wild orangutans for sale into the pet trade. This practice is closely tied to what is called swidden agriculture: as locals burn fires to clear forested areas, orangutans within those areas flee from the conflagration and are captured for meat or sale.

International guidelines and laws protect orangutans. Notably, the World Conservation Union has developed criteria to identify threatened species and published the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), under which trade in orangutans or orangutan parts is illegal. There are also national laws and programs to protect orangutans. Unfortunately, compliance and enforcement remain problematic.

The Association of Zoos and Aquariums' Ape Taxon Advisory Group (AZA Ape TAG) has supported conservation initiatives such as anti-poaching patrols and law enforcement, additional research and support from zoos, improved management of protected areas and support of sanctuaries, and increased community involvement to help protect apes.

Recognizing the growing threat of unsustainably grown palm oil, in early 2014, the Association of Zoos and Aquariums (AZA) assembled a multi-institutional task force to examine issues related to palm oil production and to develop an AZA position statement. In September 2014, the board of the AZA adopted an official position on palm oil. After adopting this position, the AZA then joined the Round Table on Sustainable Palm Oil (RSPO) in order to represent the views of its member institutions with key stakeholder in the palm oil industry and to advocate for environmentally sustainable production.

  • Be a smart consumer, and check the ingredients label. More than 50 percent of packaged foods, as well as many soaps, cosmetics and household products, contain palm oil. Always choose certified palm oil products that support sustainable production and prevent deforestation.
  • Share the story of this animal with others. Simply raising awareness about this species can contribute to its overall protection.

The Great Ape House and Think Tank are home to seven orangutans: Kiko, Kyle, Bonnie, Iris, Batang, Lucy and Redd. The orangutans are highly social but semi-solitary in the wild, so they live in small, flexible social groups at the Zoo. The two males, Kiko and Kyle, are not housed together, but the females have the flexibility to choose which group to join. The older orangutans at the Zoo are hybrids of Bornean (Pongo pygmaeus) and Sumatran (Pongo abelii) orangutans—they have one Bornean parent and one Sumatran parent. Orangutans are managed by the Association of Zoos and Aquariums' Species Survival Plan (SSP), which seeks to maintain a genetically diverse, and healthy population of both Bornean and Sumatran orangutans.

Kiko is an adult male hybrid orangutan. Weighing in at 230 pounds, he is easily recognizable by his large cheekpads and long hair. Kiko routinely brachiates (swings hand over hand) on the O-Line and can be impatient if keepers don’t move quickly enough to his liking. He was born at the Smithsonian’s National Zoo in 1987.

Kyle is an adult male Bornean orangutan. Like the Zoo’s other male orangutan, Kiko, Kyle sports large cheekpads and long hair. Kyle is bold, playful and seeks attention from his keepers and the other orangutans. He was born at the Cleveland Metroparks Zoo in December 1996 and came to the Smithsonian’s National Zoo in 2004 as part of the Bornean Orangutan Species Survival Plan.

Lucy is an adult female hybrid orangutan. The oldest of the Zoo’s orangutans, Lucy often delights visitors by sitting up at the glass. She is the only orangutan that chooses not to travel the O-Line. Lucy was born at the Zoo in 1973.

Bonnie is an adult female hybrid orangutan. Bonnie travels the O-Line frequently, but unlike most of the other orangutans, she usually does not choose to quickly cross from one end to the other, but instead likes to sit on top of one of the towers and watch the crowds down below. She has had one offspring, Kiko. Bonnie was born at the Rio Grande Zoo in 1976 and arrived at the Smithsonian’s National Zoo in 1980.

Iris is an adult female hybrid orangutan. She’s charismatic and can be quite silly and playful, but also quite stubborn at times. She is the star of several cognitive research programs and enjoys participating in daily research demonstrations at Think Tank. She was born at the Zoo on April 15, 1987, and was named after the IRS (Internal Revenue Service) because of her birth date.

Batang is an adult female Bornean orangutan. She has pale skin on her face, especially around her eyes and mouth, and is smaller in stature than the Zoo’s other female orangutans. Batang tends to be very social she enjoys spending a few days with some of the orangutans, then switches groups, spending a few days with the other orangutans. Batang was born in December 1996 at the Lincoln Park Zoo and came to the Smithsonian’s National Zoo in 2004 as part of the Bornean Orangutan Species Survival Plan (SSP).

Redd is the first Bornean orangutan born at the Smithsonian's National Zoo in 25 years. He was born Sept. 12, 2016 to mother Batang and father Kyle. Zoo staff selected the name “Redd” for the male infant orangutans are known as the “red ape.”

Longest Animals with Motherhood Period after Humans:

1. Elephants: You all know that elephants are the world’s largest babies. But still elephant mothers are greatly efficient in controlling their big babies. After the 22 months of pregnancy, every elephant born are blind at first and they completely depends on their mother. Mothers work hard and find enough food for them so that they can feed their babies with enough milk for proper development.

2. Orangutans: Possibly you know that orangutans have to wait for 8 long years between births and this is one of the longest inter birth time in the animal kingdom. After a newborn orangutan is born, they are completely dependent on their mothers for about two years. Even the first four months of this period a baby will never lose physical contact with their mothers.

3. Great Hornbills: The cases of hornbills are a bit unique from the others. When hornbills lay eggs, they find a hollow tree and seal themselves inside with the eggs. Now the father hornbill collects food for the mother and feeds her at the end of the day. After the egg hatches, slowly the hornbill mother starts training the chicks.

4. Polar Bears: After getting pregnant, a polar bear needs to double her weight for the nourishment of their babies. When a baby cub is born, it weighs about 2 pounds and they don’t have any vision. Till the baby develops and acquire a weight of about 30 pounds, mother will never leave them. So up to next few years, each and every polar bear mother works hard on their babies to train them and make them completely an adult.

5. Emperor Penguins: After an emperor penguin lays egg, she will walk about 50 miles to the ocean to catch fish as foods for their babies. During this time, the male penguin will take care of the baby and only handover it to the mother after she returns. The chicks are actually very valuable to the penguins because they lay only one egg each year.

6. Koala: when a koala baby is born, they don’t have any ears, eyes and fur. But the mother koalas perform their duty and help them to grow and develop the tolerance by feeding them her own feces. They spend about 6 months inside their mothers pouch feeding on milk which helps them in forming their missing parts.

7. Alligators: Alligators are known to have the most eco friendly pregnancy. She will make a nest out of a heap of rotten vegetations that naturally produces heat that is helpful for egg hatching. Once the babies come out from the eggs, mother will carry them around in their jaws for protection. They will spend first few years eating fish, snails etc.

8. Cheetah: Cheetahs are regarded as very good moms because of their patience level. They only have four to six cubs to care for and you should know that these cubs are not born with survival instincts. It completely depends on the mothers how they will teach their babies to hunt and collect food for themselves. Even they need to protect themselves from the predators. Male cheetahs live in a group as siblings for lifetime but the females
leave the group after six months or later.

9. Grey kangaroo: Grey kangaroos can have two joeys at a time. Joeys will not get out of the pouch until and unless they are 9 months old. Even after getting out of the pouch they don’t become completely independent. It takes more than one year to become completely self dependent. During this period it is the duty of the mothers to take care of their joeys.

10. Orca: Normally we think that human mother’s don’t get any rest during the first month after a new baby is born, but there are other animals too those who work more hard than humans just only for their babies. Actually orca claves don’t sleep for the first month of their life and hits the water continuously running. So the mother orca also doesn’t sleep with their babies. They also continuously swim which helps them to avoid predators and build up important muscle.

11. Frilled Shark: Though a very little is known about this shark but still scientists say that frilled shark probably have the longest gestation period of any vertebrate. They carry their babies for about 3.5 years. But the explanation for this long pregnancy is slow metabolism. The young ones develop in eggs inside the female and she gives birth to her tiny sharks once they develop completely.

12. Wolf Spiders: We all know that most of the spiders hang their eggs from the web but the wolf spider moms strap their eggs with their body and carry it with them. Now once the egg hatches, the mother carries them on her back until they are old enough to care of themselves.

13. Alpine Salamander: They are mostly found in the Alps across the western and Eastern Europe. Most of the salamanders lay eggs and their pregnancies last for about 2 to 4 years. Yes it’s too long.

14. Giraffe: It is one of the most popular animals in the world but very few of us know about their motherhood life. Actually giraffe is an animal that can be pregnant again while they are nursing the previous ones. Mother Giraffes spend most of their life in nursing or getting pregnant again.

15. Killer Whale: Normally the pregnancy of a killer whale lasts for 15-18 months. After a calf is born, they stay with their mother in groups and learn about various things that they will need in future to survive.

Animals are nothing less than the humans and that can be easily proved by this article. If you really read about these amazing animals and their habits, you will get to learn about a lot of things. Here the most interesting part is that, the more you will learn, the more you will fall in love with the animals.


We found that foraging juvenile crayfish respond to approaching shadows with two discrete and incompatible behaviors they either immediately stop their forward locomotion or they produce MG-mediated tail-flips that rapidly thrust them backwards. None of the presented shadows were ever ignored.

We observed inter-individual variability among crayfish exposed to the same type of stimulus. For example, in response to shadows that moved at medium velocity, about half the animals chose to tail-flip, whereas the other half produced stops. All tested animals were kept under the same controlled conditions they were equally sized and were fed an equal amount of food at the same time on the same day. Because they showed very similar latencies for initiating their food search, it appears that animals that tail-flipped and animals that stopped were equally motivated to forage. Since all animals were only tested once using a single shadow presentation, we don't know whether individuals had a predisposition for one defensive behavior or the other and whether this choice preference may also be echoed in other behavioral situations. However, variability in antipredator behaviors is common and has been described in several other model systems including rodents, where the prey's choice of freezing or fleeing in response to an approaching predator is often based on individual differences(Eilam et al., 1999 Edut and Eilam, 2004 Eilam, 2005).

Dichotomous antipredator behaviors have been reported for other invertebrate and vertebrate animals for example, in response to distant predators, freezing responses often dominate while fleeing is elicited as the predator closes in on the prey (Ranter,1976 Ranter,1977 Ydenberg and Dill,1986). Moreover, threats occurring during inescapable confinement have been shown to cause freezing more than fleeing in several species of mammal (Blanchard et al.,2001).

We found that the number of tail-flips was reduced in favor of stops when shadows moved towards the animals at high velocities. The effects of different predator attack speeds on prey escape behavior have been sparsely studied. One recent report showed that blue tits dodge sideways more often when exposed to a fast-approaching predator model than when attacked at low speed(Lind et al., 2002). In our study, crayfish exposed to fast shadows may have experienced `inescapable'situations because the high predator attack speeds may have made a timely escape response physiologically impossible. Thus, in response to such inescapable attacks, tail-flipping behavior could have decreased because the associated costs of tail-flipping (e.g. loss of energy, increasing the distance to the food, enhancing visibility) may have outweighed any benefits this escape strategy has over the stopping strategy. This possibility requires further investigation, including measuring the escape latencies of crayfish in relation to shadow positions and testing how crayfish respond to shadows that approach from the back – a situation in which MG-controlled tail-flips could be maladaptive.

Stopping, tail-flipping, and foraging are mutually exclusive behaviors,i.e. they cannot happen at the same time. Backward walking and defense posture inhibit the LG neurons in adult crayfish(Glantz, 1974a Glantz, 1974b Beall et al., 1990), and Bowerman and Larimer (Bowerman and Larimer,1974) described a single descending interneuron in crayfish brain connectives that upon activation suppressed all ongoing movements and froze the animal in position. Therefore, it seems plausible that neurons responsible for temporarily freezing juvenile crayfish inhibit neurons that promote forward walking and the MG neurons but relevant analyses of the actual circuitry have yet to be conducted.

To our knowledge, neurons that connect visual inputs to the MGs have not been described a possible consequence of sparse documentation of MG-mediated tail-flips in response to visual stimuli observed in freely behaving crayfish. Prior to this study, MG activity evoked by a purely visual stimulus was only reported once, and shadows were found to be insufficient to reliably evoke MG tail-flips (Wine and Krasne,1972). Visual stimuli primarily activate Non-G circuitry that produces tail-flips of varying angles and directions(Wine and Krasne, 1972 Wine and Krasne, 1982). Wiersma (Wiersma, 1961)reported giant-mediated responses to visual stimulation but this was before the nature of Non-G tail-flips was recognized the tail-flips observed by Wiersma were most probably mediated by Non-G circuitry(Wine and Krasne, 1972).

Here we show for the first time that MG escape tail-flips are frequently used as the initial response to moving shadows. Consistent activation of the MGs in response to shadows may be facilitated by a number of factors: the animals were searching for food when stimulated, they were in motion and they were of juvenile stage. Therefore, the motivational state, behavioral state and developmental state of the animals may have affected the thresholds for visually elicited MG tail-flips. The complete absence of Non-G tail-flips as the primary response to moving shadows in our study may be explained by the relatively high stimulus velocities we used Non-G tail-flips are characterized by longer response latencies than giant-mediated tail-flips,which make them an ineffective escape strategy when rapid responses are required (Wine and Krasne,1972 Reichert and Wine,1983 Kramer and Krasne,1984). The importance of the MG circuit in mediating adaptive escape responses is further supported by two recent reports: the MGs are frequently activated during aggressive encounters between two crayfish when a sudden drop in MG threshold identifies the loser of the fight(Herberholz et al., 2001), and activity in the MG circuit underlies most escape responses when juvenile crayfish are attacked by natural predators such as dragonfly nymphs(Herberholz et al., 2004).

By successfully identifying the MG neurons as major contributors to decision-making in crayfish, we can now take advantage of their accessibility for intracellular physiological experiments. These future investigations will provide a deeper understanding of the neural mechanisms underlying decision-making processes and behavioral choice.

The Psychological Basesfor our Bond with Animals

Attachment theory

There is a long history of scholarship examining attachment theory, the emotional relationship between the infant and mother (caregiver), exploring the exchange of comfort, care, and pleasure associated with the interaction ( Bowlby, 1958 Ainsworth and Bowlby, 1991). The first attachment theorist was John Bowlby (1958), who was very much influenced by animal ethologists, especially Konrad Lorenz and his studies of imprinting. This psychological connectedness between infants and their mothers starts at birth but is part of human behavior throughout life and is the bases for our interactions with significant people in our lives ( Bowlby, 1988). The concept of attachment to pets is widely accepted as the best explanation of the relation with our companion animals attachments to pets are often viewed as being even more secure than those with people ( Zilcha-Mano et al., 2011 Cromer and Barlow, 2013). All the psychological scales used to assess our relation with our pets are based on human attachment theory ( Beck and Madresh, 2008). Like all emotional needs, at times, the attachment people have to their pets can be exaggerated and even pathological, interfering with normal daily functioning ( Rynearson, 1978), but for the most part, our relation with companion animals is beneficial to all involved.

An extension of attachment theory is the concept of the transitional object, an object, like a blanket or stuffed toy, which the infant uses to help shift from interacting only with the mother to other objects. The object, more portable than the mother, can provide the security needed during times of stress ( Winnicott, 1969). The “transition” is the infant changing from viewing the world as only “me” to “not me.” Children especially view pets has serving the same roles of traditional transitional objects, and that too may be part of the many roles pets play in our lives ( Triebenbacher, 1998).

Social support theory

There is considerable evidence that people with good social ties are healthier and that there are significant medical consequence of loneliness ( Lynch, 1977, 2000). Social support is the physical and emotional comfort given to us by our family, friends, coworkers, and others as it is important to people that they are part of a community who love and care for them. More than three decades of studies have documented that some of the social behaviors that bring comfort between people are often part of our interactions with our companion animals, especially dogs, cats, horses, and pet birds ( Beck and Katcher 1996, 2003 Katcher and Beck, 1983, 1986 Levinson, 1969). Many of the behaviors and emotions experienced when people are together are also experienced by people when they are with companion animals such as talking, feeling less lonely, finding comfort with touch, the joy of caring and nurturing, being stimulated to exercise, finding reasons to laugh, and serving as a focus of attention all of these lessen feelings of stress.

These social benefits to people are shared by our companion animals and probably for the same or at least similar reasons. Oxytocin, produced in the hypothalamus, is found in all mammals, and it has an important role in the neuroanatomy of intimacy, specifically in sexual reproduction, in particular during and after childbirth ( Lee et al., 2009). Oxytocin release is associated with pair-bonding in all mammals studied, including monogamous rodents ( Young and Wang, 2004) and is believed to enhance the feelings of well-being ( IsHak et al., 2011). Dog owners gazing at their pet experience an oxytocin release, more than just seeing any dog, indicating a positive emotion ( Nagasawa et al., 2009). But a true “bond” is mutual and it is not surprising that dogs exhibit an oxytocin release when engaging in a positive social interaction, like being stroked, by a human ( Mitsui et al., 2011 Kis et al., 2014). Stroking a horse reduces its heart rate ( Lynch et al., 1974) and likely results in an oxytocin release as well. It is interesting to note that the tamed foxes discussed earlier had greater oxytocin concentrations than the non-tame controls ( Belyaev, 1979), indicating that domestication is both a physiological and a morphological process, and both enhance the bonding between people and their domestic animals.

Domestication has changed our relationship with animals, and perhaps also not surprisingly, it has changed the relationship of animal with people. Dogs have been domesticated the longest of all animals ( Morey, 1994), and they uniquely exhibit behaviors that are very much part of the human world. Dogs can discriminate familiar and unfamiliar human faces by sight ( Huber et al., 2013), and unlike no other animal, can follow the direction of the point or gaze of a human ( Hare et al., 2002 Hare and Tomasello, 2005). Being able to ascertain or understand the intentions or knowledge of others is a cognitive ability known as having a theory of mind. Not having this ability is often seen in those with autism spectrum disorder (ASD) and attention deficit hyperactivity disorder ADHD. Only the domestic dog can, without any special training, anticipate the intentions of a person just from viewing his or her behavior. Dogs can also discriminate people just from their faces just as humans can. But humans are clever animals too, as they can recognize positive and negative affects from just the face of a dog, even people who never owned a dog ( Schirmer et al., 2013). Just as the human brain (amygdala activation) is activated by the sight of animals ( Mormann et al., 2011), the canine brain (caudate activation) responds differentially to the odors of familiar and unfamiliar people ( Berns et al., 2014).

Events during Mitosis

Interphase: Cells may appear inactive during this stage, but they are quite the opposite. This is the longest period of the complete cell cycle during which DNA replicates, the centrioles divide, and proteins are actively produced. For a complete description of the events during Interphase, read about the Cell Cycle.

Prophase: During this first mitotic stage, the nucleolus fades and chromatin (replicated DNA and associated proteins) condenses into chromosomes. Each replicated chromosome comprises two chromatids, both with the same genetic information. Microtubules of the cytoskeleton, responsible for cell shape, motility and attachment to other cells during interphase, disassemble. And the building blocks of these microtubules are used to grow the mitotic spindle from the region of the centrosomes.

Prometaphase: In this stage the nuclear envelope breaks down so there is no longer a recognizable nucleus. Some mitotic spindle fibers elongate from the centrosomes and attach to kinetochores, protein bundles at the centromere region on the chromosomes where sister chromatids are joined. Other spindle fibers elongate but instead of attaching to chromosomes, overlap each other at the cell center.

Metaphase: Tension applied by the spindle fibers aligns all chromosomes in one plane at the center of the cell.

Anaphase: Spindle fibers shorten, the kinetochores separate, and the chromatids (daughter chromosomes) are pulled apart and begin moving to the cell poles.

Telophase: The daughter chromosomes arrive at the poles and the spindle fibers that have pulled them apart disappear.

Cytokinesis: The spindle fibers not attached to chromosomes begin breaking down until only that portion of overlap is left. It is in this region that a contractile ring cleaves the cell into two daughter cells. Microtubules then reorganize into a new cytoskeleton for the return to interphase.

Cancer cells reproduce relatively quickly in culture. In the Cancer Cell CAM compare the length of time these cells spend in interphase to that for mitosis to occur.


Nick Dale / EyeEm / Getty Images

With an average lifespan of 177 years, tortoises are considered one of the longest living vertebrates on Earth. One of their oldest known representatives was Harriet, a Galápagos tortoise that died of heart failure in 2006 at the age of 175 at a zoo owned by the late Steve Irwin. Harriet was considered the last living representative of Darwin's epic voyage on the HMS Beagle. A Seychelles tortoise named Jonathan, at 187, recently made it into the Guinness World Records as the oldest known living land animal.

Life cycle of the mysterious and long-dead dodo revealed by bone study

Bulbous-beaked, plump and puny-winged, the dodo has been immortalised by humans in art, literature and song.

But while the peculiar animals have inspired a panoply of research, not least as to whether they were really bird-brained or as corpulent as portraits implied, much about the dodo’s life has remained a mystery until now.

Scientists studying remains of the extinct avians say they have managed to put flesh on the bones of the dodo’s existence, revealing aspects of their life from when they laid eggs to how quickly they reached adulthood, and even that they shed and regrew their plumage each year.

The dodo’s annual cycle, including moulting, egg laying and a period of arrested growth during the summer months, when cyclones and poor weather are common in Mauritius. Photograph: D. Angst et al/Scientific Reports

“Before our study the only things we knew about the ecology of these birds was that they were a big pigeon [with a body mass of] about 10 kilos,” said Delphine Angst, a palaeontologist and first author of the research from the University of Cape Town.

Native to the island of Mauritius in the Indian Ocean, the dodo was wiped out in the 17th century after the arrival of Dutch sailors and the animals that came with them, with hunting, competition for food and habitat destruction all contributing to the bird’s demise.

But, despite contemporary records – including those from one Thomas Herbert who after dropping by Mauritius described the dodo in 1634 as having eyes like diamonds, “her clothing downy feathers, her train three small plumes, short and inproportionable” – little is known about the birds, with most records far from scientific.

Now researchers have managed to fill in some of the gaps.

Thomas Herbert, who visited Mauritius in the mid-17th century, described the dodo as having eyes like diamonds. Photograph: The Natural History Museum, Lond

Writing in the journal Scientific Reports, Angst and colleagues from the Natural History Museum in London and Tring describe how they examined under a microscope thin cross-sections of 22 leg and wing bones, thought to be from 22 different dodos.

The results reveal that, like the majority of modern birds, dodo bones have three layers of tissue. However, previous research in modern birds has shown that the outermost tissue is only found in adults.

“As soon as they achieve sexual maturity [the] bone tissue [develops] very slowly – and we can see that in the cross-sections,” said Angst.

The finding proved illuminating. “For the first time we can say that for sure these specimens are juvenile, even if it looks like it is almost an adult in terms of size,” said Angst, adding that the results showed that the chicks grew rapidly after hatching.

And there’s more. Female birds, notes Angst, lay down a special type of tissue inside their bones when they ovulate, with the tissue providing a supply of calcium for egg production. “In our samples we found several specimens with this specific kind of central bone and then we [can tell] for sure that this specimen is a female and it is a female during ovulation, which is quite cool,” said Angst, adding that for the other bones, without the extra tissue, it was unclear to which sex they belonged.

The study also shed light on the birds’ plumage.

When birds moult they use calcium from the inside layers of their bones to build new feathers, leaving telltale holes in the internal bone walls – a feature, the authors note, seen in the bones of birds ranging from penguins to pigeons. “It is exactly what we see for the dodo – for these specimens we can say that they died when they were actually moulting,” said Angst.

The researchers believe that differing historical descriptions of the dodo are not contradictory or wrong, but describe the birds at different phases of the moulting cycle. Photograph: Agnès Angst

That could help explain why contemporary descriptions of dodos differed significantly.

“It was usually believed that the descriptions are different because they were wrong. But the descriptions were not wrong. Actually they describe the dodo in different states of moulting.” said Angst. The authors propose that mariners who described the birds as having a downy plumage probably saw them just after moulting began, with those describing dodos as sporting grey or black feathers seeing them between periods of moulting.

Further tell-tale signs within the bones allowed the team to unpick just when such events occurred.

When resources are scarce, the outer layer of bone stops growing, leaving a line. In the dodos, these lines recur regularly, suggesting arrested growth was a seasonal event – most likely, the authors say, reflecting the summer months from November to March when cyclones and other poor weather is common in Mauritius.

By looking at thickness of the bone deposited between such lines, the researchers were then able to determine the time of year that the dodos ovulated or moulted.

“In the specimens that are moulting, just after the [line] a tiny, tiny amount of bone is deposed - that means that the moulting happened just after the last summer,” said Angst.

Transverse sections of hindlimb bones of the dodo showing resorption cavities, which are interpreted as evidence of moult. Photograph: D. Angst et al/Scientific Reports

The upshot, says Angst, is that dodos probably moulted between March and July – a suggestion that fits with the historical accounts of the bird’s plumage – with ovulation likely occurring early in August and chicks reaching full size by November, before the bad weather began.

Daniel Field, an avian palaeobiologist from the University of Bath said that new research was a fascinating illustration of how creative scientific techniques can unpick the biology of long-extinct creatures.

“The authors of this study have done a wonderful job filling important gaps in our understanding of how the dodo lived over 300 years after the last dodo died,” he said.


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