Estimated to be about 300 thousand species of plants, these living organisms get their energy from sunlight through photosynthesis. Before any animal walked on the land, plants had already grown there. About 500 million years ago during the Devonian period, the first plants colonized this new environment and permanently altered it in the process.
Birds have feathers, wings, warm blood, two legs to walk, and can lay eggs. Around 10,000 living species of bird roam around the planet. From the South pole to Norh pole, these descendants from dinosaurs diversity is a sign of their success.
Reptiles (class Reptilia) are cold blooded and have scales or scutes covering their skin. They are four limbed animals and lay eggs. With the exception of Antarctica, reptiles can be found in all the continents. With more than 6,800 species of reptiles present on the earth today, crocodiles and alligators, snakes, turtles and lizards form the major group. As they are cold blooded they keep themselves warm in the sun.
There are more than 30 thousand different species of fish in the waters all over the world. All fish have gills and are "cold blooded vertebrate aquatics".
The word amphibian means two lives. This is very fitting for most amphibians, as they spend part of their lives in water and part of their lives on land. Frogs, for instance, lay their eggs in water which then hatch into tadpoles.
Mammals are a class of vertebrate (back boned/internal bones) animals characterized by sweat glands, and a neocortex region in the brain. Unique characteristics of the mammal include a modified sweat gland that is used for milk production, hair, and three middle ear bones. Mammals are a diverse class of animal with approximately 5,400 species, 1,200 genera, 153 families, and 28 orders. They range in size from the tiny Bumblebee Bat
(believed to be the smallest mammal) to the huge Blue Whale
(largest animal to have ever existed). For some other interesting facts about mammals, see the bottom of this page. Click on the pictures below to explore the animal kingdom.
Facts about mammals
- Aside from monotremes, all mammals give birth to live young rather than lay eggs. The Platypus is an example of a montreme.
- Mammals have teeth that specialize in cutting and teeth that specialize in chewing and grinding.
- Mammals have a four-chambered heart.
- Placentals, the largest group of mammals, use a placenta during gestation.
- Rodentia (mice, rats, etc.), Chiroptera (bats), Carnivora (dogs, cats, bears, meat-eaters), and Cetartiodactyla (deer, goats, sheep, herbivores) make up the four largest orders within the placentals.
- The sauropsid line split into what would become modern-day birds and reptiles with the synapsid branch leading to mammals.
- The Jurassic Period saw the first true mammals while modern mammals appeared in the Palaeogene Period
- Mammals use two bones for hearing that their ancestors used for eating.
- Most mammals have seven cervical vertebrae.
- Mammalian lungs have a honeycombed structure.
- Mammalian skin is made up of three layers; epidermis, dermis, and hypodermis, however, this characteristic is found in all vertebrates.
- Mammals are the only animals with hair
- Most mammals are endothermic; they produce their own body heat.
- The training or learning a mammal experiences when it's young is diverged from its dependence on its mother.
- The ability from young mammals to learn from experience is a primary reason for the evolutionary success of the mammal.
- Some mammals are completely solitary aside during reproduction while others form complex social groups.
- Mammals evolved from four-legged ancestors.
- Aquatic mammals (dolphins, whales) have fins evolved from legs.
- There are four mammalian groups that are fully aquatic.
- Bats are the only mammal that can truly fly.
- The original purpose of lactation (milk production) is thought to have been to keep eggs moist.
- Fossils from the mid-Jurassic period, ~164 million years ago, contain the earliest evidence of fur or hair.
- Mammals are one of the 6 main classes of animals
- Nearly all mammals have what are called "baby-teeth". Some exceptions include the anteater, which has no teeth at all.
- The word mammal comes from the Latin mamma, meaning breast. This is derived from milk production in females for their young.
- All mammals are warm-blooded, which means they maintain a constant body temperature despite environmental conditions.
- The largest mammal on land, and largest animal on land, is the African Bull Elephant.
- The tallest animal on the planet is also a mammal, the Giraffe.
- There are people suffering from Agrizoophobia, which is the fear of wild animals. Can you imagine that?
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