Milwaukee Public Museum: Tropical Rainforest
LIFE CHANGES THROUGH GROWTH AND DEVELOPMENT
Growth and Development: What is the Difference?
While growth in living organisms is a change in overall size and proportions, development is change in form. Some animals, like the frog and the Morpho butterfly, have one form when they are young and a very different form when they are adults. This often allows the immature form and the adult form to occupy different habitats and use different resources. This phenomenon is called metamorphosis.
The Frog’s Story
Take a look at the development of the fertilized frog egg.
1. After a sperm cell penetrates the egg cell, the egg begins to divide. First, there are two cells, then four, then eight, and so on. The egg becomes a hollow ball with a single layer of small cells. This is called a blastula.
2.Then, some of the cells are forced to move inwardly, change shape, and grow as the blastula becomes a gastrula. The gastrula is a three-layered embryo, made of ectodermal, mesodermal and endodermal layers.
3. Organs begin to develop. The ectoderm gives rise to skin and its derivatives, the sense organs and the brain and spinal cord. The mesoderm gives rise to muscle, connective tissue, the circulatory system and most of the excretory and reproductive systems. The endoderm gives rise to the lining of most of the digestive tract, most of the respiratory tract, the urinary bladder, liver, pancreas and some endocrine glands.
4.In about five days, this fertilized frog egg develops into a tadpole. Tadpoles have gills for breathing underwater but they also breathe through their skin. After a few weeks or months, the tadpole loses its tail and gills. It grows lungs and legs as it transforms into a frog.
Milwaukee Public Museum: Tropical Rainforest
LIFE CHANGES THROUGH GROWTH AND DEVELOPMENT
Growth and Development: What is the Difference?
While growth in living organisms is a change in overall size and proportions, development is change in form. Some animals, like the frog and the Morpho butterfly, have one form when they are young and a very different form when they are adults. This often allows the immature form and the adult form to occupy different habitats and use different resources. This phenomenon is called metamorphosis.
The Frog’s Story
Take a look at the development of the fertilized frog egg.
1. After a sperm cell penetrates the egg cell, the egg begins to divide. First, there are two cells, then four, then eight, and so on. The egg becomes a hollow ball with a single layer of small cells. This is called a blastula.
2.Then, some of the cells are forced to move inwardly, change shape, and grow as the blastula becomes a gastrula. The gastrula is a three-layered embryo, made of ectodermal, mesodermal and endodermal layers.
3. Organs begin to develop. The ectoderm gives rise to skin and its derivatives, the sense organs and the brain and spinal cord. The mesoderm gives rise to muscle, connective tissue, the circulatory system and most of the excretory and reproductive systems. The endoderm gives rise to the lining of most of the digestive tract, most of the respiratory tract, the urinary bladder, liver, pancreas and some endocrine glands.
4.In about five days, this fertilized frog egg develops into a tadpole. Tadpoles have gills for breathing underwater but they also breathe through their skin. After a few weeks or months, the tadpole loses its tail and gills. It grows lungs and legs as it transforms into a frog.