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Juvenile (animal)
A juvenile is an individual organism (especially an animal) that has not yet reached its adult form, sexual maturity or size. Juveniles can look very different from the adult form, particularly in colour, and may not fill the same niche as the adult form. In many organisms the juvenile has a different name from the adult (see List of animal names). Some organisms reach sexual maturity in a short metamorphosis, such as ecdysis in many insects and some other arthropods. For others, the transition from juvenile to fully mature is a more prolonged process—puberty in humans and other species (like higher primates and whales), for example. In such cases, juveniles during this transformation are sometimes called subadults. Many invertebrates cease development upon reaching adulthood. The stages of such invertebrates are larvae or nymphs. In vertebrates and some invertebrates (e.g. spiders), larval forms (e.g. tadpoles) are usually considered a development stage of their own, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whale
Whales are a widely distributed and diverse group of fully Aquatic animal, aquatic placental mammal, placental marine mammals. As an informal and Colloquialism, colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and porpoises. Dolphins and porpoises may be considered whales from a formal, Cladistics, cladistic perspective. Whales, dolphins and porpoises belong to the order Cetartiodactyla, which consists of even-toed ungulates. Their closest non-cetacean living relatives are the hippopotamuses, from which they and other cetaceans diverged about 54 million years ago. The two parvorders of whales, baleen whales (Mysticeti) and toothed whales (Odontoceti), are thought to have had their Most recent common ancestor, last common ancestor around 34 million years ago. Mysticetes include four Neontology, extant (living) Family (biology), families: Balaenopteridae (the rorquals), Balaenidae (right whales), Cetotheriid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adolescence
Adolescence () is a transitional stage of human Developmental biology, physical and psychological Human development (biology), development that generally occurs during the period from puberty to adulthood (typically corresponding to the age of majority). Adolescence is usually associated with the Teenager (word), teenage years, but its physical, psychological or cultural expressions may begin earlier or end later. Puberty typically begins during preadolescence, particularly in females. Physical growth (particularly in males) and cognitive development can extend past the teens. Age provides only a rough marker of adolescence, and scholars have not agreed upon a precise definition. Some definitions start as early as 10 and end as late as 30. The World Health Organization definition officially designates adolescence as the phase of life from ages 10 to 19. Biological development Puberty in general Puberty is a period of several years in which rapid physical growth and psycholog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Childhood
A child () is a human being between the stages of childbirth, birth and puberty, or between the Development of the human body, developmental period of infancy and puberty. The term may also refer to an unborn human being. In English-speaking countries, the legal definition of ''child'' generally refers to a minor (law), minor, in this case as a person younger than the local age of majority (there are exceptions such as, for example, the consume and purchase of alcoholic beverage even after said age of majority), regardless of their physical, mental and sexual development as biological adults. Children generally have fewer Children's rights, rights and responsibilities than adults. They are generally classed as unable to make serious decisions. ''Child'' may also describe a relationship with a parent (such as sons and daughters of any age) or, Metaphor, metaphorically, an authority figure, or signify group membership in a clan, tribe, or religion; it can also signify being str ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Puppy
A puppy is a Juvenile (organism), juvenile dog, generally one less than 12-18 months old. Puppies are markedly underdeveloped and dependent on their mothers at birth (displaying ''altriciality''), but healthy puppies grow quickly and begin walking thereafter. Puppies generally weigh shortly after birth, depending on the breed. A puppy's coat colour may change as the puppy grows older, as is commonly seen in breeds such as the Yorkshire Terrier. ''Puppy'' refers specifically to young dogs, while ''pup'' may be used for other animals such as wolf, wolves, Pinniped, seals, giraffes, guinea pigs, rats, or sharks. Prenatal development Dogs go through prenatal development before they are born, just like all animals do. The germinal stage, the embryonic stage, and the fetal stage are the three phases that make up this development. The first stage of prenatal growth in dogs is known as the germinal stage, which starts at fertilization and lasts for about two weeks. The ferti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kitten
A kitten is a Juvenile (organism), juvenile cat. After being born, kittens display primary altriciality and are fully dependent on their mothers for #Establishing immunity, survival. They normally do not open their eyes for seven to ten days. After about two weeks, kittens develop quickly and begin to explore the world outside their nest. After a further three to four weeks, they begin to eat solid food and grow baby teeth. Domestic kittens are highly social animals and usually enjoy human companionship. Etymology The word "kitten" derives from the Middle English word , which in turn came from the Old French or . Juvenile big cats are called "cubs" rather than kittens; either term (but usually more commonly "kitten") may be used for the young of smaller wild felidae, felids, such as ocelots, caracals, and lynxes. Development A feline Litter (animal), litter usually consists of two to five kittens, but litters with one to more than ten are known. Kittens are typically born af ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fledge
Fledging is the stage in a flying animal's life between egg, hatching or birth and becoming capable of flight. This term is most frequently applied to birds, but is also used for bats. For altricial birds, those that spend more time in vulnerable condition in the nest, the nestling and fledging stage can be the same. For precocial birds, those that develop and leave the nest quickly, a short nestling stage precedes a longer fledging stage. All birds are considered to have fledged when the feathers and wing muscles are sufficiently developed for flight. A young bird that has recently fledged but is still dependent upon parental care and feeding is called a fledgling. People often want to help fledglings, as they appear vulnerable, but it is best to leave them alone. The USA National Phenology Network defines the phenophase (or life cycle stage) of fledged young for birds as "One or more young are seen recently departed from the nest. This includes young incapable of sustained ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embryo
An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm cell. The resulting fusion of these two cells produces a single-celled zygote that undergoes many cell divisions that produce cells known as blastomeres. The blastomeres (4-cell stage) are arranged as a solid ball that when reaching a certain size, called a morula, (16-cell stage) takes in fluid to create a cavity called a blastocoel. The structure is then termed a blastula, or a blastocyst in mammals. The mammalian blastocyst hatches before implantating into the endometrial lining of the womb. Once implanted the embryo will continue its development through the next stages of gastrulation, neurulation, and organogenesis. Gastrulation is the formation of the three germ layers that will form all of the different parts of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amniote
Amniotes are tetrapod vertebrate animals belonging to the clade Amniota, a large group that comprises the vast majority of living terrestrial animal, terrestrial and semiaquatic vertebrates. Amniotes evolution, evolved from amphibious Stem tetrapoda, stem tetrapod ancestors during the Carboniferous geologic period, period. Amniota is defined as the smallest crown clade containing humans, the Greek tortoise, and the Nile crocodile. Amniotes are distinguished from the other living tetrapod clade — the anamniote, non-amniote lissamphibians (frogs/toads, salamanders/newts and caecilians) — by: the development of three fetal membranes, extraembryonic membranes (amnion for embryonic protection, chorion for gas exchange, and allantois for metabolic waste disposal or storage); thicker and keratinized skin; rib, costal respiration (breathing by expanding/constricting the rib cage); the presence of adrenal cortex, adrenocortical and chromaffin cell, chromaffin tissues as adrenal g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tadpole
A tadpole or polliwog (also spelled pollywog) is the Larva, larval stage in the biological life cycle of an amphibian. Most tadpoles are fully Aquatic animal, aquatic, though some species of amphibians have tadpoles that are terrestrial animal, terrestrial. Tadpoles have some fish-like features that may not be found in adult amphibians, such as a lateral line, gills and swimming tails. As they undergo metamorphosis, they start to develop functional lungs for breathing air, and the diet of tadpoles changes drastically. A few amphibians, such as some members of the frog family Brevicipitidae, undergo direct development i.e., they do not undergo a free-living larval stage as tadpoles instead emerging from eggs as fully formed "froglet" miniatures of the adult morphology (biology), morphology. Some other species hatch into tadpoles underneath the skin of the female adult or are kept in a pouch until after metamorphosis. Having no hard skeletons, it might be expected that tadpole fos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spider
Spiders (order (biology), order Araneae) are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude spider silk, silk. They are the largest order of arachnids and rank seventh in total species diversity among all Order (biology), orders of organisms. Spiders are found worldwide on every continent except Antarctica, and have become established in nearly every land habitat. , 53,034 spider species in 136 Family (biology), families have been recorded by Taxonomy (biology), taxonomists. However, there has been debate among scientists about how families should be classified, with over 20 different classifications proposed since 1900. Anatomy, Anatomically, spiders (as with all arachnids) differ from other arthropods in that the usual body segmentation (biology), segments are fused into two Tagma (biology), tagmata, the cephalothorax or prosoma, and the opisthosoma, or abdomen, and joined by a small, cylindr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertebrate
Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebrata with some 65,000 species, by far the largest ranked grouping in the phylum Chordata. The vertebrates include mammals, birds, amphibians, and various classes of fish and reptiles. The fish include the jawless Agnatha, and the jawed Gnathostomata. The jawed fish include both the Chondrichthyes, cartilaginous fish and the Osteichthyes, bony fish. Bony fish include the Sarcopterygii, lobe-finned fish, which gave rise to the tetrapods, the animals with four limbs. Despite their success, vertebrates still only make up less than five percent of all described animal species. The first vertebrates appeared in the Cambrian explosion some 518 million years ago. Jawed vertebrates evolved in the Ordovician, followed by bony fishes in the Devonian. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
