The life cycle of vertebrates

The life cycle of vertebrates

The life cycle of vertebrates starts with the production of the reproductive cells of an individual and ends with the production of the reproductive cells of the next generation.

Biology

Keywords

vertebrates, life cycle, development, ontogeny, reptile, amphibian, bird, mammal, fishes, common carp, kangaroo, grass snake, thrush, red deer, chicken, edible frog, nidicolous, placental, adult, marsupial, precocial, egg, embryo, tadpole, gill, lung, fertilisation, mating, soft-shelled egg, bird egg, breast, breast milk, placenta, fetus, incubation, nest, morula, fry, animal, spine, biology

Related items

Scenes

Adult animals

  • Fishes
  • Amphibians
  • Reptiles
  • Precocial birds
  • Atricial birds
  • Marsupial mammals
  • Placental mammals

Fishes

  • spawn - A mass of unfertilised eggs released by the female carp. Its surface is sticky and can therefore adhere to aquatic vegetation.
  • hatchling - It develops from the fertilised egg. Initially, it takes nutrients from the yolk sac found under the stomach.
  • fry - A young animal capable of feeding on its own.
  • adult carp - A fully grown female carp can lay 150,000 to 200,000 eggs per kilogram body weight. During the breeding season, the female and the male swim close to each other and release their eggs and sperm, respectively, into the water.

Fishes are gonochoric animals but generally there is little difference between female and male individuals. The spawning of fishes depends on water temperature.

The process starts with the female and the male releasing their reproductive cells into the water. The male fish uses external fertilisation to fertilise the eggs laid by the female.

Most fishes have a simple life cycle, that is, they do not go through metamorphosis. The offspring resemble the adults but they are smaller and weaker.

Amphibians

  • spawn
  • embryo
  • hatchling
  • tadpole
  • hind legs develop
  • forelegs develop
  • tail disappears
  • adult frog

Amphibians have spectacular courtship rituals and use mostly external fertilisation.

Amphibians develop by metamorphosis. Larvae that hatch from the fertilised eggs are called tadpoles; they undergo major changes before reaching their adult form. The fish-like tadpoles breathe through gills. As they grow, their legs gradually develop while the gills and the tail disappear.

Reptiles

  • egg
  • hatchling
  • young snake
  • adult snake

Reptiles use internal fertilisation; that is, during mating, the male discharges its reproductive cells inside the female’s body. The fertilised egg is soon surrounded with a nutrient-rich yolk and a soft shell.

Most reptiles lay their eggs into the ground and the ideal incubation temperature for the eggs is provided by solar radiation.

Reptiles have a simple life cycle, that is, they do not go through metamorphosis. Their development does not depend on the presence of water.

Precocial birds

  • egg - It has a light colour and weighs about 50–60 g.
  • chick - It hatches after 21 days of incubation and is covered with down feathers.
  • rooster and hen - The male is called a rooster and the female a hen. Males are larger than females and have brightly coloured plumage and a large, red comb. Females have less colourful plumage, mostly brown; and a smaller comb. Egg cells are constantly developing in the hen's body. They become eggs even if they are not fertilised. However, chicks only develop from fertilised eggs.

Birds are gonochoric animals, that is, there are separate female and male individuals. Sexual dimorphism is usually present: males typically have a colourful plumage while females are more dull-coloured.

Birds use internal fertilisation, i.e. during mating, the male discharges its reproductive cells inside the female’s body through the cloaca. The fertilised egg is soon surrounded with a nutrient-rich yolk and calcified shell. The ideal incubation temperature for the eggs is provided by the body heat of the brooding parent.

Birds have a simple life cycle, that is, they do not go through metamorphosis.

The offspring of precocial birds are developed enough to follow their parents soon after hatching.

Atricial birds

  • egg - It is bluish green with brownish red spots and weighs about 6–7 g.
  • nestling - It is fed caterpillars, insects and earthworms by the parents.
  • young blackbird - It starts feeding on its own after 2–3 weeks of leaving the nest. Until then, it is fed by the parents.
  • male and female - Male blackbirds have black plumage and orange beaks, while females have brownish grey plumage. Males take on a bigger role in raising the chicks. Common blackbirds can raise three broods a year.

Birds are gonochoric animals, that is, there are separate female and male individuals. Sexual dimorphism is usually present: males have a colourful plumage while females are more dull-coloured.

Birds use internal fertilisation, i.e. during mating, the male discharges its reproductive cells inside the female’s body through the cloaca. The fertilised egg is soon surrounded with a nutrient-rich yolk and calcified shell. The ideal incubation temperature for the eggs is provided by the body heat of the brooding parent.

Birds have a simple life cycle, that is, they do not go through metamorphosis.

When the offspring of altricial birds hatch, they are undeveloped and are not capable of feeding on their own for a long time.

Marsupials

  • morula - The offspring develops in the mother’s uterus for 32–36 days.
  • newborn kangaroo - The embryo-like, immature baby kangaroo weighs only a few grams. It climbs into its mother's pouch unaided right after birth.
  • infant kangaroo (joey)
  • young kangaroo - The young is raised in its mother's pouch for a few months, which it leaves more and more frequently as it grows. Eventually, it becomes independent at the age of 10 months.
  • adult male and female - The male is much larger than the female. Females reach sexual maturity after 18 months.

Mammals derive their name from the mammary glands, which are modified sweat glands. The young are fed milk produced by the the mother's mammary glands.

The offspring of marsupials develop in the mother’s uterus only for a short period of time and are very undeveloped at birth. They spend the first stage of their lives in the mother’s pouch.

Placental mammals

  • morula - The offspring develops in eight months in the mother's uterus.
  • embryo - The offspring develops in eight months in the mother's uterus.
  • fawn - The newborn fawn weighs 7–15 kg and can walk soon after birth.
  • stag and hind - The male deer is called a stag, while the female is called a hind. Only the stag has antlers, which can grow very large.

Mammals derive their name from the mammary glands, which are modified sweat glands. The young are fed milk produced by the the mother's mammary glands.

The offspring of placental mammals develop in the mother’s uterus for a long period of time and are born relatively developed. Placental mammals derive their name from the placenta which provides nutrients to the foetus.

Related items

African elephant

The largest land mammal on Earth.

Anatomy of the spinal cord

The spinal cord is the part of the central nervous system running inside the spinal column from which spinal nerves branch out.

Axolotl

The axolotl, also known as Mexican salamander, is an amphibian species that keeps its gills even in adulthood.

Common blackbird

This animation demonstrates birds' bones and eggs through the example of the common blackbird.

Common carp

Freshwater fish used as food in many parts of the world.

Common European viper

A species of venomous snakes widespread in Europe. Its bite is rarely fatal to humans.

Darwin's legendary voyage

Darwin's legendary voyage aboard HMS Beagle played a crucial role in the development of the Theory of Evolution.

Diversity of light-detecting organs

Several analogous types of eyes have developed independently through convergent evolution.

Eastern grey kangaroo

One of the largest marsupials.

Edible frog

This animation demonstrates the anatomy of amphibians through the example of a common species of frogs.

Grass snake

A type of snake with a characteristic spot on its neck.

How do fish breathe?

Blood vessels in fishes' gills absorb oxygen and release carbon dioxide.

Livestock

This animation presents animals commonly kept as livestock and the primal cuts of their meat.

Marsh harrier

Marsh harriers are birds of prey found almost worldwide.

Red deer

Red deer are even-toed ungulates, ruminants. Their males have spectacular antlers.

Types of dentition in mammals

The dentition of different species of mammals reflect their feeding habits.

Vertebrate brain evolution

During the evolution of vertebrates the relative development of brain areas has changed.

Western jackdaw

Groups of western jackdaws are frequently found in cities. Konrad Lorenz analysed the complex social behaviour of these animals.

Added to your cart.