What Are the Developmental Stages of a Frog?
Aug 04, · The developmental stages of most frogs are the egg stage, various tadpole stages, the froglet stage and the adult frog stage. The complete growth cycle of the frog generally takes between 12 and 16 weeks. The life cycle of a frog begins when the . Aug 11, · The life cycle of a frog consists of three stages: egg, larva, and adult. As the frog grows, it moves through these stages in a process known as metamorphosis. Frogs are not the only animals to undergo metamorphosis; most other amphibians also undergo remarkable changes throughout their life cycles, as do many species of invertebrates.
Animal Life Cycle : The life cycle of an animal shows how they grow and change over time. Most animals such as mammals, fish, reptiles and birds have very simple life cycles. But Amphibians, like frogs, have a more complicated life cycle. Amphibians means that they can live in water or on land. The study of amphibians and reptiles is called Herpetologyand those who study them are called Herpetologists. The life cycle of a frog goes through FOUR stages of life. They undergo metamorphosis changes and grows at each stage.
What is Metamorphosis? The Egg is the first phase of the life cycle of a frog. A frog begins life as a fertilized egg. A female frog lays a lot of eggs thousands of eggs at once usually in or near water.
Eggs are covered in jelly like substance which makes them slippery. The jelly protects them from other animals eating the eggs. Now the eggs are ready to hatch into tadpoles. Tadpoles hatch from eggs. When the tadpole is disgusted, it does not look exactly like a frog, but rather like a fish. Tadpole has no legs, at this point of its life cycle.
It breathes using gills and moves like a fish. It uses its long tail to swim. Tadpoles eat small water plants and algae. During this time, the tadpole begins to have two hind legs and has a long body along with its head. With the help of its two hind legs it can easily jump around instead of just swimming.
At this stage, the tadpole begins to develop the lungs, so that it can also breathe out of water when it becomes a frog. With all these changes, the tadpole looks a bit more like a small frog.
In this stage the lungs and two front legs also grow. Its long tail becomes shorter and shorter. Due to the lungs, the froglet also floats above the water to breathe air. At this stage of the life cycle, a froglet does not require anything else to eat because it uses the nutrients stored in its tail as food. Now it looks like a young frog. The adult frog is the fourth and how to place ribbons on army dress blues stage of life cycle of a frog.
Now it is perfectly fit to leave the water and live on the land. The mother frogs return to the water to lay eggs, and the life cycle of a frog begins again. There are over 6, species of frogs worldwide. Frogs were the first land animals with vocal cords. The goliath frog of West Africa is the largest frog in the world.
It can grow to 15 inches and weigh up to 7 pounds. Toads are frogs. Croaking is used by male frogs as a way to attract females. Both males and females return to the same breeding grounds year after year. The bulging how to get a discount on a cruise of most frogs allow them to see all around like in front, to the sides, and partially behind them.
Many frogs can leap more than 20 times iv what number is this body length. The Marsupial Frog keeps her eggs in a pouch like a kangaroo. When the eggs hatch into tadpoles, she opens the pouch with her toes and spills them into the water. Paedophryne amauensisthe smallest frog in the world has been discovered in Papua New Guinea by a US-based team.
Funny Jokes. Parenting Tips. Skip to content. Life Cycle of a Frog. What is Life Cycle of a Frog. A life cycle is made up of a series of different phases that each living thing undergoes during its life. But not all plants and animals have the same life cycle. Life Cycle of a Frog. Stage 1: Egg. Eggs of the Frog. Stage 2: Tadpole.
It takes about 21 days for tadpoles to form. Stage 3: Froglet. The Froglet. Stage 4: Adult Frog. Egg — It is covered in Jelly-like substance. Tadpole — Tadpole breathes through gills. At early stage Tadpole has no legs, but later at this stage only it develop two back hind legs.
It has a long tail. With the help of its tail It swims like a fish. Froglet — Froglet develops two fore front legs.
Tail of the Froglet shrinks. Froglet develop lungs and gills disappear. Froglet became a young frog. Adult Frog — It can leave the water and live on the land. It starts what are the stages of frog development insects. The mother frogs lay eggs. Common Frog Facts For Kids. Goliath Frog, the Largest Frog in the World. Paedophryne amauensis, the smallest frog in the world [pic via google image]. Solar System. Jokes For Kids.
Parents Corner. More Animal Facts. More Plant Facts. Latest Posts. Here you will learn about different life cycles of animals. Life Cycle of a Butterfly. Life Cycle of a Grasshopper. Life Cycle of a Mosquito. Life Cycle of a BedBug.
It includes three stages: Egg, larva, and adult
To consolidate once again the stages of development of the frog, the scheme will be our assistant in this: fertilized egg, represented by an egg, - a tadpole with external gills - a tadpole with internal gills and skin breathing - a formed tadpole with lungs, limbs and a gradually disappearing tail - frogs - an adult individual. Post-Neural or Pre-Hatching Development: The neurula of Rana tigrina develops into tail-bud embryo, having bulges of gill-plates, optic bulges, one on either side, stomodaeal groove at antero-ventral side of head and a pair of ectodermal adhesive organs, cement glands or oral suckers in the form of conical protuberances, which later on unite to form U or V-shaped adhesive sucker. Jul 09, · This divides the egg into two halves forming the 2-cell stage. The second cleavage forms the 4-cell stage. The cleavage furrow again runs through the poles but at right angles to the first furrow. The furrow in the third cleavage runs horizontally but in a plane closer to the animal than to the vegetal pole. It produces the 8-cell stage.
Frogs lay their eggs in water in early spring. In pseudocopulation or mating, the male frog firmly clasps the body of the female frog by his forelegs and enlarged thumb pads nuptial pads.
These nuptial pads help in clasping the body of female. This sexual embrace is called amplexus. As the eggs are extruded through the cloaca of female oviposition , the male deposits sperm cells over them insemination.
Thus, fertilisation is external, taking place in water. The mesolecithal eggs of frog enclosed in a protective gelatinous albumen are laid in water.
The cluster or masses of eggs which remain stick together is called spawn. A spawn of Rana tigrina may have to ova. The spawn is laid during pseudocopulation or amplexus. In frog, fertilisation is external and occurs at once in water outside the body of the oviparous female.
The entire sperm penetrates the ovum anywhere around the animal hemisphere. If fertilisation is delayed, the albumen layers around the ovum become too thick for the sperm to pass through them and the ovum also starts to show degeneration. In the fertilisation process, vesicular sperm nucleus and vesicular female nucleus or pronuclei fuse together to form zygote nucleus.
The fusion of both male and female pronuclei is called amphimixis. The fertilised egg or zygote is about 1. The upper half of the zygote or animal hemisphere is pigmented black and it contains the cytoplasm and a nucleus, the lower vegetal hemisphere is white and full of yolk.
On one side between the black and white areas is a gray crescent region which marks the future dorsal side. At this region cortex becomes thin and this area is crescent-shaped.
The plane passing through the centre of grey crescent and the animal pole defines the median plane of bilateral symmetry. It coincides with the embryonic axis and is the only plane which separates the egg into two equivalent parts, each containing half the crescent material. Cleavage or segmentation is holoblastic and unequal. A vertical furrow from the animal to the vegetal pole divides the zygote completely into two equal-sized cells.
A second vertical furrow at right angles to the first divides the zygote into four cells. The third cleavage is horizontal and above the equator which segments the zygote into upper four smaller, black-coloured cells, and lower four larger, white-coloured cells. The cells formed by cleavage are blastomeres, the upper black blastomeres are called micromeres, and lower white ones are macromeres.
Further cleavages divide the micromeres more rapidly than the lower macromeres whose division is hindered by yolk. At this stage the whole embryo acquires a characteristic appearance reminiscent of a mulbery and so it is called morula.
About fourth and fifth cleavage stages a small space, the blastocoel appears between the blastomeres of morula. In the beginning it is like narrow crevices between blastomeres of morula, which gradually increases as the cleavage goes on. The blastocoel shifts more and more towards the animal pole due to more rapid multiplication of the micromeres, and infiltrated by water and albuminous fluid secreted by the surrounding cells.
The blastocoel also enlarges due to uptake of more water. As cleavage proceeds, the blastomeres arrange themselves into a true epithelium called blastoderm. It is two-cell thick towards animal pole of the egg and forms the roof of blastocoel, while the sides and floor of the blastocoel is occupied by multilayered blastoderm of large yolky blastomeres.
Thus, the resulting embryo having fluid-filled blastocoel is called blastula. In the blastula, the blastomeres which have to form different germinal layers and different organs of the adult frog can be observed by artificial-vital staining methods of Vogt and prospective organ region maps or fate maps have been prepared. According to the fate map studies, the whole surface of blastula can be divided into the following three areas:.
The neural ectoderm occurs largely on the future dorsal side of blastula, while the epidermal ectoderm occupies the antero-ventral side of the blastula. Inside the neural ectoderm occurs a small sub-area that develops into the eye of the embryo. The sub-area of nose, sucker, ears and mouth are present inside the epidermal ectoderm.
It is crescentic gray area, the marginal zone along the equator of blastula. It has blastomeres for the formation of notochord and mesoderm of the embryo. The large area of dorsal side of the gray crescent is occupied by notochordal cells.
Beneath the notochordal area, toward the vegetal pole lies a narrow strip of cells which form the pre-chordal plate of the embryo. On either sides of notochordal area, the part of grey crescent forms the segmental muscles somites and tail mesoderm is a narrow strip of cells on the dorsal side, toward animal hemisphere.
Lateral and ventral parts of grey crescent give rise to ventro-lateral mesoderm. Gastrulation is a process of migration and re-arrangement of prospective organ forming cells already present in the blastula. It is brought about by several types of morphogenetic movements taking place at the same time.
Certain prospective endodermal cells just beneath the mid- dorsal point of gray crescent of blastula assume the elongate shape of a bottle and move toward the interior of the blastula.
Their steadily elongating necks remain attached to the surface of the blastula with the outermost cementing layer. Thus, as the bulky-cell bodies move inward, a pull exerted along their attenuated necks and creates an indentation at the surface. With continued multiplication and attenuation of bottle cells, the invagination deepens, and expands internally to form the archenteron or gastrocoel and its outer opening original indentation is called the blastopore lying at the future posterior end.
The area immediately above the blastopore is the dorsal lip of blastopore. Gradually, the blastoporal invagination extends circulo-laterally, so the blastopore becomes crescentic, then horse-shoe-shaped and finally circular. Thus, lateral lips and ventral lip of blastopore are also formed and fused with each other along with dorsal lip, forming circular lip of blastopore.
The endoderm of foregut involute over the dorsal lip along chorda-mesoderm. The rest of prospective endoderm of vegetal region passes into the interior of the embryo passively and come to lie in the floor of gastrocoel. The endodermal cells bordering the dorsal lip of blastopore form the prospective pharyngeal endoderm, which is followed by pre-chordal plate, notochord and tail mesoderm.
When dorsal lip is formed, the pharyngeal endoderm cells involute over the dorsal blastoporal lip. These cells move to the interior and their place take the converging prechordal plate cells and they also involute. Behind these cells are present notochordal cells and tail mesoderm cells, which also involute and move to the interior. As these materials move inward around the dorsal lip they become considerably narrowed and elongated. The prospective pharyngeal endoderm in later stages of gastrulation forms the foregut whose lateral, ventral and anterior walls consist of a thin layer of endoderm.
The dorsal wall of foregut consists of prechordal plate and anterior tip of notochord. The notochord cells of the posterior region also involute and move anteriorly over the dorso-lateral lips of blastopore. Thus, the notochord forms the mid-dorsal wall of the archenteron, which is in the form of strip. The prechordal plate also forms the dorsal wall of the archenteron in front of notochord.
The tail mesoderm remains near the blastopore, and marks the posterior end of the embryo. The mesoderm i. After rolling inside the entire mesoderm i. Thus, it occupies the entire space between ectoderm and endoderm except a small space at the anterior end of embryo where mouth will be formed in late stage.
Throughout gastrulation the embryo retains its spherical shape and a uniform size. After involution of gastral endoderm and entire mesoderm, this space is taken up by the ectoderm epidermal and neural. The expansion of ectoderm from animal hemisphere over the vegetal hemisphere is an active process.
The presumptive epidermal ectoderm expands in all directions, but the presumptive neural ectoderm expands mainly in the longitudinal direction, i. Thus, the ectoderm expands up to the circular lip of blastopore through which unpigmented endodermal cells is visible, which form the yolk plug. Due to contraction of circular lip of blastopore, yolk plug slightly comes outside.
Thus, in the end of gastrulation a new cavity gastrocoel is formed and the blastocoel is obliterated. Due to accumulation of endodermal mass on the future ventral side, the gravity is shifted and embryo rotates within fertilisation membrane so as to bring its dorsal side uppermost. The protruding yolk plug gradually withdraws to the interior, and the blastopore steadily contracts to form a slit-like opening in the end of gastrulation.
Thus, gastrulation changes the radially symmetrical single layered blastula into a spherical, bilaterally symmetrical, triploblastic gastula having a head-to-tail axis. It is externally covered by ectoderm and endoderm, and mesoderm lies in the interior. Gastrocoel forms the lumen of the forming gut. Its lateral walls and floor is formed by the endoderm and its roof is formed of chorda-mesodermal cells. By the time gastrulation is being completed, the ectoderm along the mid-dorsal side of the embryo thickens to form a pear-shaped medullary or neural plate.
The neural plate cells change in shape and become elongated and arranged themselves into a columnar epithelium. The epidermal cells remain more or less flat and arranged as a stratified epithelium usually two cells thick.
The edges of the neural plate become thickened and slightly raised above the general level as ridges called neural folds. The neural plate narrows transversely especially in its posterior parts and the neural folds raised higher due to which a neural groove is formed along its length.
The neural folds grow and fuse with each other in the mid-dorsal line to form a neural tube. The lateral epidermal ectoderm of either side also meet and fuse at the mid-dorsal line above the neural tube, thus, enclosing it. The neural tube remains open in front for a time as a neuropore, posteriorly the neural folds cover and fuse over the blastopore so that the cavity of the neural tube communicates with the archenteron by a neurenteric canal which is the narrow canal-like opening of blastopore.
The anterior broad part of the neural tube forms the brain and the remaining narrow posterior part becomes the spinal cord. The neural tube also forms neuroglia cells of the nervous system. The cells from the neural folds that come to lie between the dorsal epidermis and the dorsal part of the neural tube are the neural crest cells.
These lie along the dorso-lateral sides of the neural tube. The neural crests give rise to melanocytes, dorsal root ganglia of spinal nerves, parts of the autonomic nervous system and adrenal glands, and to some mesenchyme cells which form the visceral arches. The notochord cells separates off from the prechordal plate of mesoderm as a narrow rod of cells.
This notochordal rudiment also separates off from the rest of the chorda-mesodermal mantle and notochordal cells transform into colligocytes.
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