Animals are multicellular, eukaryotic living beings. They have some distinct features like the ability to move, make sounds, collect food materials, and other activities.
They are the dominant living beings on earth. These include small animals like insects to intelligent large animals like human beings.
They differ from plants in their ability to move from place to place and dependent on others for their food. Most of them are dependent on plants while few are dependent on other animals.
They have a brain that evolves further and they can make decisions.
They can be classified into different types based on their food requirements, habitats, size, reproduction, body anatomy, etc.
Types of animals by evolution
- Sponges
- Coelenterates
- Worms
- Mollusks
- Arthropods
- Echinoderms
- Fishes
- Amphibians
- Reptiles
- Birds and
- Mammals (includes humans)
Sponges
These are multicellular organisms mostly found in marine waters. The cells do not form a tissue so they have no organs.
Each cell in the body survives on its own but all the cells are intact. They have a column-shaped body.
Coelenterates
These animals are more evolved than sponges. They have tube-like bodies and a mouth.
They even have tentacles (appendages) to swim. They move from one place to another in search of food and shelter.
Ex: Hydra which lives in freshwater.
Worms
These are the biggest categories of organisms. They exist as normal living organisms and also as parasites in other higher animals.
They have a thread-like or tape-like body. They are slender and very long. They are of different types ex: Earthworms.
Arthropods (insects)
These are animals that have joint legs. They are commonly called as insects. They are herbivorous and some of them are carnivorous.
They are also parasites causing diseases to other animals.
They also act as parasites (lice). They are one of the biggest categories of animals available. They include house fly, mosquitoes, spiders, butterflies, etc.
Echinoderms
This is a class of animals including starfish.
They live in the sea and oceans.
Till echinoderms, we come across invertebrate animals. From there on we see the evolution of vertebrate animals.
Fishes
These are the animals well known to man. They are present in both freshwater and marine waters.
They breathe with gills and swim with fins. They lay eggs and give birth.
Amphibians
These animals as the name indicates are able to live on both land and in water.
This group of animals includes especially the frogs. They are carnivores and also herbivores.
Reptiles
These animals are poisonous snakes, lizards, and ferocious crocodiles. See the characteristics of reptiles.
They are mostly carnivores except for tortoise. They live either on water or on land. Not on both.
Birds
These are the animals that have a special ability to fly. Birds can fly miles together due to their strong forelimbs. From these animals and mammals, we get the concept of warm-blooded animals. They have constant body temperature irrespective of external climate conditions.
They are carnivores but can eat even plant material. They lay eggs and give birth to young ones.
Mammals
These animals are highly evolved of all. They give direct birth to young ones.
They feed the babies with milk from their mammary glands.
Types of animals based on anatomy.
Based on the vertebral column
a. Vertebrates. Have vertebral column, spine connecting brain
b. Invertebrates. No vertebral column
Based on body temperature.
a. Poikilotherms (changing temperature)
b. Isoltherms (constant body temperature)
Reproduction
a. Hermaphrodites.
b. Male or female animals.
Respiratory system
a. Lungs
b. Gills.
c. Tracheae.
Progeny
a. From eggs
b. Direct birth.